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The effects of cattle on the natural heritage of Scotland : Scottish Natural Heritage Commissioned Report No. 203 (ROAME No. F04AA103)

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This review aimed to clarify the benefits and detrimental effects of cattle on a range of unimproved habitats, wildlife species and on the landscape in Scotland. Specifically the review aimed to: a) collate existing published and unpublished information on the impact of cattle on specific unimproved habitats, wildlife species and the landscape; b) summarise the information, consider the generality of the findings and draw conclusions about the impacts of cattle, including benefits and adverse effects of cattle and the associated farming systems and; c) identify areas of uncertainty in current knowledge. The review concentrated primarily on information from Scotland and other parts of the UK, but where relevant, information from outside the UK was included.
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COMMISSIONED REPORT
For further information on this report please contact:
Barbara Bremner
Scottish Natural Heritage
Great Glen House
Leachkin Road
INVERNESS
IV3 8NW
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E-mail: barbara.bremner@snh.gov.uk
This report should be quoted as:
Wright, I.A., Pakeman, R.J., Dennis, P., Dalziel, A.J. and Milne, J.A. (2006). The effects of
cattle on the natural heritage of Scotland. Scottish Natural Heritage Commissioned Report
No. 203 (ROAME No. F04AA103).
This report, or any part of it, should not be reproduced without the permission of Scottish Natural Heritage.
This permission will not be withheld unreasonably. The views expressed by the author(s) of this report should
not be taken as the views and policies of Scottish Natural Heritage.
© Scottish Natural Heritage 2006
Commissioned Report No. 203
The effects of cattle on the
natural heritage of Scotland
(ROAME No. F04AA103)
Background
This review aimed to clarify the benefits and detrimental effects of cattle on a range of unimproved habitats,
wildlife species and on the landscape in Scotland. Specifically the review aimed to:
a) collate existing published and unpublished information on the impact of cattle on specific unimproved
habitats, wildlife species and the landscape;
b) summarise the information, consider the generality of the findings and draw conclusions about the
impacts of cattle, including benefits and adverse effects of cattle and the associated farming systems and;
c) identify areas of uncertainty in current knowledge.
The review concentrated primarily on information from Scotland and other parts of the UK, but where
relevant, information from outside the UK was included.
Main findings
Cattle are less selective in their grazing behaviour than other domestic herbivores.
This results in different impacts on unimproved, semi-natural habitats compared to, for example, sheep.
Compared to other domestic grazers, cattle result in:
o a more structurally diverse sward;
o a reduction in the cover of tussock forming species;
o creation of more niches for plant regeneration.
There is a lack of empirical objective information on the impacts of cattle grazing for many unimproved habitats.
For the habitats for which there is empirical information, in most cases, grazing by cattle is either beneficial
or at least neutral,
provided that the grazing is at an appropriate stocking density and seasonal pattern
.
Cattle should not graze bog vegetation (blanket bog and raised lowland bog).
There have been no scientific studies of foraging behaviour of different breeds of cattle.
There is very little information on the effects of cattle grazing on priority species.
As well as having a direct effect on habitats, cattle can affect the natural heritage by being part of the
farming system.
Potential negative effects of cattle farming systems include trampling and poaching, bank erosion and
pollution of water courses from farm yard manure, slurry and silage effluent. These impacts can all be
minimised by adhering to good practice guidelines.
Positive impacts of cattle farming systems include dung, where it supports high populations of invertebrates,
fodder production which can result in hay meadows and small-scale cereal production.
The effects of cattle on the natural heritage of Scotland
Commissioned Report No. 203 (ROAME No. F04AA103)
Contractor: Macaulay Research Consultancy Services
Year of publication: 2006
COMMISSIONED REPORT
Summary
For further information on this project contact:
Barbara Bremner, Scottish Natural Heritage, Great Glen House, Leachkin Road, Inverness IV3 8NW
Tel: 01463 725000
For further information on the SNH Research & Technical Support Programme contact:
Senior Management Unit Advisory Services, Scottish Natural Heritage, Great Glen House, Leachkin Road, Inverness IV3 8NW
Tel: 01463 725000 or ascg@snh.gov.uk
Contents
Summary
1 INTRODUCTION 1
1.1 National and international perspectives 1
1.2 Objectives, methods and structure of the review 1
1.3 Land cover 2
2 CATTLE POPULATIONS AND THEIR FORAGING BEHAVIOUR 5
2.1 Distribution and numbers of cattle 5
2.2 Foraging behaviour and diet selection 5
2.3 Summary 15
3 EFFECTS OF CATTLE ON UNIMPROVED HABITATS 16
3.1 Neutral grasslands 16
3.2 Base-rich grasslands 16
3.3 Acidic grasslands 17
3.4 Periodically flooded grasslands 19
3.5 Coastal grasslands including cliff-tops 20
3.6 Machair 20
3.7 Rush pasture 21
3.8 Lowland heath 22
3.9 Moorland 23
3.10 Lowland raised bog 25
3.11 Blanket bog 26
3.12 Semi-natural woodland 27
3.13 Wood pasture 29
3.14 Wetland 29
3.15 Fen 29
3.16 Coastal heath 31
3.17 Saltmarsh 31
3.18 Scrub including montane scrub 32
3.19 Summary of impacts of grazing by cattle on habitats 33
4 EFFECTS OF CATTLE ON PRIORITY SPECIES 34
4.1 List of priority species 34
4.2 Overview of effects of grazing and trampling on priority habitats 37
5 EFFECTS OF CATTLE FARMING SYSTEMS ON THE NATURAL 45
HERITAGE
5.1 Introducing cattle into farming systems 45
5.2 Provision of winter fodder 46
5.3 Positive effects on the natural heritage of farming systems 47
involving cattle
5.4 Negative effects on the natural heritage of farming systems 48
involving cattle
5.5 Examples of systems where cattle are used to benefit the natural 50
heritage
5.6 Conclusion 51
6 CONCLUSIONS 52
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SUMMARIES OF PAPERS AND REPORTS COVERING THE EFFECTS 53
OF CATTLE ON THE NATURAL HERITAGE
REFERENCES
List of figures
Figure 1.1 Main land cover types in upland Scotland 4
Figure 2.1 Distribution of beef cows in Scotland, 1990 6
Figure 2.2 Distribution of beef cows in Scotland, 2004 7
Figure 2.3 Distribution of all beef cattle in Scotland, 1990 8
Figure 2.4 Distribution of all beef cattle in Scotland, 2004 9
Figure 2.5 Difference in beef cattle livestock units 1990–2004 10
Figure 2.6 The range of scales involved in herbivore grazing 12
Figure 2.7 The pattern of digestibility of different vegetation types 13
throughout the year
Figure 2.8 The percentage of
Nardus
in the diet of sheep and cattle at 14
different levels of intertussock biomass (based on Grant
et al.
,1985)
List of tables
Table 1.1 Total area of selected land cover types in the uplands of Scotland 3
(from the Land Cover of Scotland, 1988, MLURI 1993a and b)
Table 2.1 Summary of grazing attributes of herbivores 11
Table 3.1 Summary of effects of cattle on habitats 33
Table 4.1 List of priority animal and plant species that may be affected 34
by grazing for each habitat
Table 4.2 Summary of key studies of impacts of grazing by cattle on birds 39
Table 4.3 Summary of key studies of impacts of grazing by cattle on 43
invertebrates
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1 INTRODUCTION
1.1 National and international perspectives
The Scottish landscape comprises large areas of unimproved, semi-natural habitats. This is especially the
case in the uplands, which are dominated by semi-natural vegetation types which have been affected by
human activities to a greater or lesser degree. There are also some important semi-natural habitats in the
lowlands. The two human-influenced activities in recent times which have had, and continue to have, most
impact on the nature of the vegetation of the uplands, apart from afforestation, are grazing by domestic and
wild large herbivores and burning.
The effect of grazing by large domestic and wild herbivores on the natural heritage value of the uplands
have been a long-standing issue (Milne
et al
., 1998). For example, McVean and Lockie (1969) argued that
in the Western Highlands, livestock and deer management was reducing soil fertility and vegetation diversity
to lower levels by the end of the 19th century. More recently, there has been an accumulation of evidence
of a decline in the area of heather moorland in Scotland (Tudor and Mackey, 1995). There has been also
a marked decline in the area and status of semi-natural woodland (Mitchell and Kirby, 1990; Roberts
et al
.,
1992). These changes lead to a reduction in the abundance of fauna (Usher and Gardner, 1998) and an
increase in the rarity of some species. However, at many sites grazing is a characteristic part of the
landscape, and reduction or abandonment of grazing can lead to loss of nature conservation and amenity
value (Fry, 1991).
The national and international significance of areas of blanket bog, montane plant communities and
ericaceous dwarf shrubs within Scotland support large bryophyte-rich and pteridophyte-rich communities with
localised world distributions and unusual breeding bird assemblages. They provide a unique landscape
of high conservation significance (Ratcliffe and Thompson, 1998). This is recognized in the range of
habitat types included in Annex 1 of the EU Habitats Directive. These include raised and active blanket
bogs, species-rich
Nardus
grassland, alpine and sub-alpine heaths, Caledonian pine woodland and sub-
Artic willow scrub. All these habitats are subject to grazing as a major influence.
Domestic livestock, including cattle, have a significant impact on many of these unimproved habitats, either
directly through grazing and trampling of habitats, or via the impacts of farming systems which include cattle.
The impact of grazing by cattle, along with the impacts of farming systems associated with cattle are
considered in this review.
1.2 Objectives, methods and structure of the review
The objectives of the review are to:
a) collate existing published and unpublished information on the impact of cattle on specific unimproved
habitats, wildlife species and the landscapes;
b) summarise the information, consider the generality of the findings and draw conclusions about the impacts
of cattle, including benefits and adverse effects of cattle and the associated farming systems; and
c) identify areas of uncertainty in current knowledge.
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The project was undertaken by reviewing the scientific literature and undertaking web-based searches for
other relevant published and unpublished information. The review concentrated primarily on information from
Scotland and other parts of the UK but, where relevant, information from outside the UK was included.
Ongoing, but unpublished research is also referred to on occasion, based on the personal knowledge of
the review team.
The structure of the review is firstly to describe the numbers and relevant characteristics of cattle (Chapter 2).
Chapter 3 reviews the impact of cattle on a range of semi-natural habitats including summarising best
practice, while Chapter 4 considers the effects of cattle on priority species. The role of cattle within farming
systems on the natural heritage is considered in Chapter 5 while Chapter 6 gives the conclusions.
The Bibliography summarises the studies that have evaluated the impacts of cattle on the natural heritage.
Finally sources of information are given in the References section.
1.3 Land cover
From the Land Cover of Scotland 1988 dataset (MLURI 1993a and b) the cover of some of the
main vegetation types relevant to this review in the uplands has been extracted and is shown in Table 1.1a.
The cover of nationally significant mosaics of each of the cover types is given in Table 1.1b. More or less
equal amounts of heather moorland and peatland dominate the upland area, covering 55.6% of the area
on their own or in mosaics with each other, and being present in other mosaics covering another 14.6% of
the area. Grasslands and bracken (14.9% of the area) cover over half of what remains and are also the
main vegetation-forming mosaics with heather and peatland (11.4% of the area). Most of the remaining
area is divided nearly equally between woodlands and scrub (5% of the area), and unclassified mosaics
(5.4% of the area). Native woodlands cover only 1% of the land area of Scotland with 91% of this occurring
in the Highlands. The distribution of land cover types is given in Figure 1.1. This shows that heather and
peatland predominate in the west and north of Scotland while rough grassland is found largely in the south
and east of Scotland.
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Table 1.1 Total area of selected land cover types in the uplands of Scotland (from the Land
Cover of Scotland, 1988, MLURI 1993a and b)
a) Major cover types
Land cover types Area (km
2
) % Corresponding habitats in Chapter 3
Good Rough Grassland 2,472.2 5.3 Neutral, base rich, acidic, coastal grasslands
and machair
Poor Rough Grassland 2,011.0 4.3 Acidic grassland, rush pasture
Bracken 117.3 0.3
Heather Moorland 6,881.5 14.8 Lowland heath, moorland, coastal heath
Peatland 6,600.2 14.2 Lowland raised bog, blanket bog
Montane 1,604.5 3.5
Rocks and Cliffs 348.1 0.7
Felled Woodlands 299.8 0.6
Semi-Natural Coniferous 75.0 0.2 Semi-natural woodland
Mixed Woodland 854.5 1.8 Semi-natural woodland
Broad-Leaved Woodland 1,024.3 2.2 Semi-natural woodland, wood pasture
Scrub 74.4 0.2 Scrub, including montane
Marshes 127.9 0.3 Wetland, fen, saltmarsh
Nationally Significant Mosaics 24,011.8 51.5
(see Table 1.1b)
Total 46,502.5 100.0
b) Nationally significant mosaics
Cover types in mosaic Area (km
2
)%
Heather Moorland Peatland 12,370.9 26.6
Poor Rough Grassland Heather Moorland 3,230.0 6.9
Good Rough Grassland Heather Moorland 1,452.9 3.1
Peatland Montane 935.5 2.0
Good Rough Grassland Poor Rough Grassland 848.0 1.8
Improved Grassland Good Rough Grassland 814.8 1.8
Good Rough Grassland Bracken 660.9 1.4
Poor Rough Grassland Peatland 634.0 1.4
Heather Moorland Montane 539.9 1.2
Unclassified 5.4
Total 24,011.8 51.6
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Figure 1.1 Main land cover types in upland Scotland
These maps are based upon the Ordnance Survey material with the permission of Ordnance Survey on behalf of the Controller of Her Majesty’s
Stationery Office © Crown copyright (2006). Any unauthorised reproduction infringes Crown copyright and may lead to prosecution or civil proceedings.
© Scottish Natural Heritage 100017908 (2006).
2 CATTLE POPULATIONS AND THEIR FORAGING BEHAVIOUR
2.1 Distribution and numbers of cattle
Information on the numbers of cattle in recent times is normally based on the June census data collected by
SEERAD. Whilst these data provide good estimates of total numbers in Scotland, they provide less useful
information on their distribution. The data are aggregated on a parish basis so it is not possible to identify
the vegetation of habitat types grazed by these cattle. Also, since 1990, those parishes containing three or
less farms have been omitted from the dataset disclosed to protect the confidentiality of the information.
Nevertheless most of the information on numbers and distribution that has been published is based on this
data set (HFRO, 1970; Harding
et al
., 1994). Although numbers per parish give some indication of grazing
impact, livestock densities per parish provide more useful figures since parishes differ in size.
In the last century hill cattle numbers have declined. Darling (1955) noted that sheep: cattle ratios had
increased from 15:1–40:1 between 1911 and 1946. Whilst hill cattle numbers increased between the
Second World War and 1970 (HFRO, 1970), their numbers have since declined. The number of breeding
beef cows in Scotland in 2004 (SEERAD, 2004) was 503,574 while in 1990 there were 541,561.
However it is not possible to estimate accurately those that graze specific habitats from currently available
statistics even although data are available at the parish level. The distribution of beef cattle, derived from
the 1990 and 2004 census, within Scotland is given in Figures 2.1–2.4. The densities of beef cattle
(livestock units (LU) per km
2
of agricultural land) are shown. This includes beef cows, beef bulls, and other
beef cattle and assumes that 1 LU is the equivalent of one adult dairy cow. Figure 2.5 shows the change,
by parish, in total beef cattle livestock units. The highest densities of beef cows are in the areas lying
between the lowland and hill areas, the traditional ‘upland‘ farms. A broadly similar pattern is evident in the
maps of all beef cattle livestock units, except that the densities are also high were there are significant
numbers of fattening cattle eg in the North East of Scotland. It is difficult to see a clear spatial pattern in the
change in beef cattle livestock units between 1990 and 2004 (Figure 2.5), but parishes where there has
been an increase in numbers appear to be mainly in the upland fringe.
The review of the Common Agricultural Policy and the introduction of the Single Farm Payment in 2005 may
bring about further changes in the cattle population in Scotland. It has been suggested that breeding cow
number in Scotland could fall by about 5% in Scotland as a whole and about 13% in the Highlands and
Islands area (Cook and Copus, 2003).
2.2 Foraging behaviour and diet selection
The direct impact of cattle on the natural heritage depends primarily upon the numbers of cattle grazing,
and the processes of defoliation, trampling and excretal return by individual animals of which defoliation
probably has the largest impact. Ultimately the impact of defoliation on the vegetation is at the individual
plant level, but the foraging choices that the animal makes within a plant community and its ranging
behaviour between plant communities also determines the impact. This means that an understanding of cattle
grazing behaviour is required across a number of geographical scales (see Figure 2.2 for a diagrammatic
representation of these scales). Different large herbivores have different impacts on vegetation by virtue of
their different feeding methods associated with their size and shape of mouth. This information is summarised
in Table 2.1 for each species of large herbivore. Cattle are unique among these large herbivores in having
a feeding method which involves a tearing action with their tongue. They also have a low ability to be
selective in selecting their diet and the minimum sward height grazed is higher than other large herbivores
cited except for horses.
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Figure 2.1 Distribution of beef cows in Scotland, 1990. (Number per ha of agricultural land)
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Figure 2.2 Distribution of beef cows in Scotland, 2004. (Number per ha of agricultural land)
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Figure 2.3 Distribution of all beef cattle in Scotland, 1990. (Number of livestock units
per ha of agricultural land)
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Figure 2.4 Distribution of all beef cattle in Scotland, 2004. (Number of livestock units
per ha of agricultural land)
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Figure 2.5 Difference in beef cattle livestock units 1990–2004. (Numbers per ha of
agricultural land)
Table 2.1 Summary of grazing attributes of herbivores (Armstrong and Milne, 1995;
Gordon and Iason, 1989; Hewson, 1989; Mitchell and Kirby, 1990; Pehrsen, 1979;
del Pozo
et al.,
1996; Wright and Whyte, 1999)
Minimum sward
Feeding method Selectivity Type height grazed
Cattle Tear with tongue Low Grazer 5cm
Horses Shearing Low Grazer 6cm
Sheep Biting/shearing High Grazer 3cm
Red Deer Biting/shearing Intermediate Grazer/browser 3cm
Goats Biting/shearing High Browzer/grazer 4cm
Rabbits Biting/shearing Very high Grazer 1cm
Mountain hares Biting/shearing High Grazer 3cm
The size of a large herbivore also has a major impact on the amount of vegetation removed through its
intake. Potential intake is determined by the metabolic live weight (live weight raised to the power of 0.75)
of the animal, ie larger animals have higher intakes, and its physiological status, for example lactating cows
have higher intakes and fatter cattle have lower intakes per unit body size. Potential intake can also
be modified by a number of factors such as the availability and quality of the vegetation, microclimate
and social behaviour. The most important modifiers of intake are available biomass and the quality
(or digestibility) of that biomass. Generally, as available biomass increases, intake by large herbivores
increases, but at a decreasing rate, until there come a point when intake ceases to increase even at higher
biomass. This relationship holds for cattle grazing perennial ryegrass/clover swards (Wright and Whyte,
1989) and there is no reason to suspect that it will not hold for semi-natural vegetation communities.
Foraging behaviour between plant communities
On most unimproved habitats grazing cattle can make choices between patches of different communities.
Cattle, like other species of large herbivore, preferentially graze on communities that offer the highest rate
of nutrient intake. They therefore tend to graze communities with higher levels of digestibility. Therefore, by
knowing the digestibility of the diet selected from different plant communities, based on research, the plant
community patch on which the cattle beast will graze can be predicted. Figure 2.3 shows the pattern of
digestibility throughout the year for some of the major plant communities of the uplands assuming that
available biomass is not limiting. Gordon (1989) described the choices made by cattle between different
plant communities on the Island of Rum throughout the year and they support the outcomes that would be
predicted on the basis of the availability of digestible nutrients of the plant communities at different times of
the year.
Such an approach does not allow for the sampling of a range of vegetation types that cattle normally make
and, hence, may overemphasise the proportion of high digestibility plant communities in the diet. It also does
not take into account shelter-seeking behaviour and social behaviour which may cause localised deviations
from selection for plant communities based on availability and digestibility. Supplementary feeding will also
cause cattle to congregate around feeding sites and lead to grazing of plant communities which would not
be predicted to be used so frequently.
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Figure 2.6 The range of scales involved in herbivore grazing
The spatial distribution of plant communities has also been shown to affect selection of plant communities by
sheep and red deer (eg Oom
et al
., 2000) but similar work has not been carried out with cattle. Thus
although the general spatial pattern of grazing may be predicted it is not yet possible to predict with any
certainty that specific spatial pattern of grazing across a landscape. This makes it difficult to predict the
precise impact of grazing by cattle at the landscape scale.
Diet selection within plant communities
Within plant communities there will be a range of plant species with different biomasses and ratios of dead
to live tissue. This leads to differences in digestibility and available biomass in a similar manner to that of
the between-community level. Grazing animals usually select a diet with a higher proportion of live material
than that found in the sward as a whole (eg Grant
et al
., 1985). This is partly due to the fact that grazing
animals tend to graze from the top of the sward down and there is a higher proportion of dead material at
the bottom of the sward and so bites taken from the top of the sward will have a lower proportion of dead
material and a higher proportion of live material than in the sward as a whole. Since cattle take deeper
bites than sheep, the difference between the sward and diet composition is greater in sheep than in cattle
but cattle still have a diet that contains a higher proportion of live plant material than that found in the
vegetation community that they graze (Grant
et al
., 1985).
A similar theoretical approach to that used to predict foraging between plant communities can be used to
predict what would be selected within a plant community. A good example to illustrate this conclusion is
the grazing of a
Nardus
and
Agrostis/Festuca
community by cattle. The
Nardus
has a higher biomass but
a much lower digestibility than the
Agrostis/Festuca
component of the community such that the intake of
digestible nutrients from the
Agrostis/Festuca
component is much higher than that of
Nardus
. The diet selected
by cattle is predominantly
Agrostis/Festuca
but the proportion of
Nardus
in the diet increases as the
availability of the biomass of
Agrostis/Festuca
declines (Figure 2.4). Because of the feeding method of cattle
associated with the size and shape of its mouth, cattle are much less selective in their feeding behaviour
than other large herbivores when selecting a diet with an intimate mix of species within a plant community.
Also trampling effects of cattle are greater than other smaller species such as sheep because of their size.
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Figure 2.7 The pattern of digestibility of different vegetation types throughout the year
Potential breed differences in foraging behaviour
The question as to whether different breeds of cattle forage in different ways is one that has been asked for
many decades. There is much anecdotal evidence to suggest that there may be differences between cattle
in foraging behaviour, but to date there is very little scientific evidence that breed differences exist
(Wright
et al
., 2002; Rook
et al
., 2004). Research is currently underway at the Institute of Grassland and
Environmental Research on whether breed influences foraging behaviour in cattle. Nevertheless many
conservation agencies prefer to use traditional breeds to promote biodiversity. The Royal Society for the
Protection of Birds, for example, uses Highland cattle on some of its nature reserves. At Vane Farm reserve
in Fife, a herd of Highland cattle is used to control rushes and maintain species-rich grassland. Highland
cattle are also used on Rum, where, as a result, there has been an increase in variety of plants in most plant
communities. However, there has been very little research done to compare the grazing behaviour, diet selection,
herbage intake and impact on vegetation of rare and traditional breeds with modern or imported breeds.
One of the few studies that has been conducted was with sheep on
Molinia
-dominated vegetation
(Newborn, 2000). Over a five-year period (1992–96) grazing by Hebridean sheep compared with
Swaledale sheep led to a consistently higher level of utilisation of
Molinia
. It is therefore possible that this
apparent preference for purple moor grass by the Hebridean sheep could be exploited to reduce the content
of purple moor grass significantly. There was a significant increase in the heather cover under grazing by
Hebridean sheep although the author could not draw any conclusions about the reasons for this, except that
further study is required to fully understand the mechanisms involved. Dwyer and Lawrence (1997) observed
that when Blackface and Suffolk ewes grazed in a field comprising improved pasture and semi-natural
vegetation, the Suffolk ewes tended to graze the improved pasture and the Blackface ewes the semi-natural
pasture. However this does not conclusively demonstrate genetic differences in grazing behaviour, since the
differences could be due to competition between the larger Suffolk sheep and the smaller Blackface ewes
for the better resource.
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Figure 2.8 The percentage of
Nardus
in the diet of sheep and cattle at different levels
of intertussock biomass (based on Grant
et al.
, 1985).
One of the difficulties in studying breed differences in grazing behaviour, is that differences between
populations of animals could be learned as well as being genetic in origin. It is well recognized that aspects
of feeding behaviour can be learned in animals, especially from their mothers (Thorhallsdottir
et al
., 1990).
Therefore any breed comparisons must take this into account.
One of the most comprehensive sources of information on foraging by cattle is
The Breed Profiles Handbook
(Tolhurst and Oates, 2001) published by the Grazing Animals Project (http://www
.grazinganimalsproject.org).
This provides description of the foraging behaviour of a number of British breeds of cattle. However it is not
clear how these descriptions were derived and little if any of the information seems to be based on sound
scientific information. There is a major gap in our knowledge about the foraging behaviour of different
breeds and to what extent genotype and learned behaviour influences diet selection and foraging. Wright
et al
. (2002) concluded that there was a pressing need for research on the potential differences between
breeds in foraging behaviour and on vegetation and other aspects of vegetation.
2.3 Summary
1 It is only possible to describe the distribution of density of cattle in Scotland approximately.
2 On the basis of digestibility and available biomass, it is possible to predict which plant communities will
be grazed by cattle at different seasons of the year. Since the digestibility of communities based on
Agrostis/Festuca
species is higher than that of other grass species, such as
Nardus
and
Molinia
, and
shrubs, such as heather, and trees, they are grazed preferentially except when limited by available
biomass. Depending on stocking density, such limitation in biomass is likely to occur in autumn and winter.
3 Preferences within plant communities are determined by the same factors as between-community
selection although cattle are less selective feeders than other large herbivores.
4 The impact at any site is a function of the density of cattle and their intake and diet selection. The latter
two variables can be predicted with some precision for the most abundant plant species although not
taking into account local factors, such as shelter, social behaviour and supplementary feeding.
5 There is little scientific information on which to draw conclusions about differences in foraging behaviour
among breeds. This does not mean that such differences do not exist, but rather that until such time as
more research has been conducted care must be taken in interpreting claims that such differences can
be used to manage particular vegetation communities for specific objectives.
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3 EFFECTS OF CATTLE ON UNIMPROVED HABITATS
3.1 Neutral grasslands
Neutral grasslands (National Vegetation Classes MG1, 5–7, 9–13) are not common in Scotland. Only one
study has been conducted on the effects of grazing by cattle (Tallowin
et al
., 2005). After five years of
grazing by cattle at different grazing pressures there was no difference in botanical diversity, but differences
in vegetation structure emerged. The cover of
Poaceae
increased under more lenient grazing pressures, but
the abundance of
Fabaceae
increased under higher grazing pressures. Abundance of
Heretoptera
, bumble
bees and spiders all increased under lower grazing pressures. There have been no comparative studies of
grazing by cattle compare to grazing by other species. However a low stocking density (eg 0.5 LU/ha year)
is likely to lead to greater structural heterogeneity in the sward than grazing by sheep. The overall level of
grazing, in terms of the amount of vegetation grazed, is likely to have a greater impact on the long-term
species composition than the type of grazer. English Nature (2001) in The Upland Management handbook
suggests the following management for upland neutral grassland (NVC types MG2–10):
flower-rich pastures and hay meadows; 5 sheep/ha or 0.75 cattle/ha at any time. Meadows must be
closed for at least 8 weeks before mowing and the aftermath should be grazed. (Countryside Council
for Wales, 1992);
damp and marshy grassland: 0.5 cattle/ha/year. (Lower stocking rates are recommended between
1 March and 30 June to reduce nest trampling. (Countryside Council for Wales, 1992).
Summary
The overall level of grazing is likely to have a greater effect that the species of grazer although cattle grazing
may lead to greater structural heterogeneity.
Best practice
On the basis of studies on other vegetation types grazing by cattle at low (0.5 LU/ha/year) stocking
densities in summer is likely to lead to greater structural diversity than grazing by sheep and in the long
term greater diversity of invertebrates. Lower stocking rates in spring and early summer will reduce nest
trampling.
3.2 Base-rich grasslands
Base-rich grasslands occur mainly in the uplands in Scotland (NVC classes CG10–14) with only about
260ha in the lowlands (NVC classes CG2, CG7 and CG10). These grassland are more species rich than
acid grasslands. No specific studies have been conducted into the impacts of cattle grazing in Scotland.
However the overall level of grazing in terms of biomass removed, including grazing by wild herbivores is
likely to have a greater effect on these grasslands than the species of grazer. Given the tendency for cattle
to select taller, coarser vegetation (see Chapter 2) it is possible that the grazing of cattle in early summer
may reduce seed setting and shedding. English Nature (2001) gives the following recommendations for the
grazing of upland calcareous grasslands (NVC types CG2, CG3, CG6, CG7, CG9, CG10):
graze stock at no more than 1 sheep/ha or 0.15 cattle/ha for any continuous period of eight weeks
between 1 May and 31 August;
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at any other time graze stock at no more than 2 sheep/ha or 0.3 LU/ha. Grazing rates may be higher
when gathering stock on up to five separate days per year (Mercer and Evans, 1997);
encourage diversity of the habitat by having some areas only grazed in autumn and others ungrazed
by stock.
The recommendations regarding stocking by cattle appear to be based on sheep equivalents as no specific
research has been conducted on cattle grazing.
On lowland calcareous grasslands Kirkham
et al
. (2003) suggest that an annual stocking rate of about
0.33 LU/ha may be appropriate. On more productive sites, which in their study were often grazed by
cattle, stocking rates were up to 0.6 LU/ha/annum. However care must be taken with these figures as firstly
all the sites were in England or Ireland and secondly no check was carried out that these stocking densities
were actually achieving the appropriate conservation objectives.
Summary
No specific information is available on the effects of cattle grazing. The overall level of grazing is likely to
have a greater effect that the species of grazer. On the basis of known differences in foraging behaviour
between species (Chapter 2), it is possible that grazing by cattle in early summer may reduce seed setting.
Best practice
No specific information on cattle grazing.
Limit grazing by cattle to 0.15 LU equivalents for any continuous period of eight weeks between May
and August.
At other times limit grazing to 0.3 LU/ha, although on very productive lowland sites higher stocking rates
may be possible.
3.3 Acidic grasslands
Acid grasslands are one of the most extensive semi-natural habitats in Britain (NVC classes U2, 4–6).
Acid grassland dominated by
Agrostis
and
Festuca
species is the most digestible, and is preferred
by grazing livestock during summer growth whilst there is a high proportion of green leaf available
(Armstrong, 1996; Mowforth and Sydes, 1987). Summer grazing reduces the accumulation of dead
material from these species in autumn. There is little direct experimental comparison of the grazing of
Agrostis–Festuca
grassland with cattle compared with other species. However, to achieve acceptable levels
of performance cattle need higher sward heights that sheep (Mayne
et al
., 2000) and cannot graze to such
short sward height as sheep (see Table 2.3). Therefore cattle-grazed
Agrostis–Festuca
swards are likely to
be taller. Taller swards, especially those grazed by cattle, have greater heterogeneity in height (Gibb and
Ridout, 1986; 1988; Wright and Whyte, 1989) and therefore have more structural heterogeneity, which
in turn is likely to lead to more diverse population of invertebrates (Dennis
et al
., 1998).
Nardus stricta
is the least palatable of the acid grassland species with a high silica content (Armstrong,
1996). Cattle are more effective than sheep at controlling
Nardus stricta
(mat-grass) of
Nardus stricta–
Galium saxatile
grassland (U5), because they are less selective and consume a higher proportion of this
species as they forage (Grant
et al
., 1985; 1987; Welch, 1986; see also Chapter 2 Figure 2.4). In contrast,
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intensive grazing by sheep will increase the proportion of
Nardus
in the vegetation because other grasses
are favoured and grazed more intensively. Cows with calves grazed on
Nardus
-dominated grassland from
June–August for six years, consumed a larger proportion of
Nardus
than was present in the sward as a whole
(Common
et al
., 1998). The outcome of two grazing treatments (lactating cows grazed to maintain either
a 4.5 or 6.5cm average sward height between tussocks) was a marked reduction in the cover and average
tussock size of
Nardus
. However, the cows of the shorter sward treatment lost condition during the period
of summer grazing, while cows grazing the taller sward gained weight and also reduced the extent of
Nardus
in the grassland, albeit at a slower rate. Thus it appears that high rates of utilisation of
Nardus
are
not compatible with high levels of nutrition and animal performance (Common
et al
., 1998) due to the lower
nutritional value of
Nardus
compared with the other species in the sward (Armstrong
et al
., 1986). In particular,
after the main period of growth the digestibility declines rapidly from the end of July and this has a negative
impact on cattle live-weight gain (Common
et al
., 1998). Thus, if lactating cows and calves are to graze
Nardus
-dominated vegetation, acceptable levels of performance can probably only be achieved from late
May until the end of July, depending on location. Outwith these periods dry stock may have to be used.
Mixed grazing of cattle with sheep on
Nardus
-dominated vegetation can result in higher levels of sheep
performance compared to sheep-only grazing. In one study (Howard and Wright, 1994) lambs gained
30g per day more when cattle were grazing with the sheep than when only sheep were present.
Molinia caerulea
(purple moor grass) typical of
Molinia caerulea–Potentilla erecta
mire (M25) is the
dominant grass species in 10% of the uplands of Britain (Bunce and Barr, 1988). Burning regimes and light
grazing tend to increase the proportion of
Molinia
in the vegetation (Common
et al
., 1997; Wildig, 2000).
Cattle can be effective at controlling the spread of purple moor grass, especially if grazed early in the
season when this grass is at its most preferred and susceptible to grazing effects. Experimental grazing of
cattle on
Molinia
-dominated vegetation reduced its area of cover and increased floristic diversity, compared
with ungrazed treatments (Grant
et al
., 1996b). Two stocking densities were used to achieve either 33%
or 66% utilization of
Molinia
. In the former case, the area of cover of
Molinia
stabilized at 60–65% after
3–5 years, whereas the cover was reduced by 86% after six years at the higher stocking density.
Wavy hair-grass,
Deschampsia flexuosa
, of
Deschampsia flexuosa
grassland (U2) is less preferred by
livestock than
Agrostis
and
Festuca
species and is mostly grazed during May–July. However, in grassland
dominated by this species it may also be eaten in winter because it is evergreen (Mowforth and Sydes,
1989). In contrast, cattle grazing failed to improve the species richness of montane Deschampsia cespitosa
grasslands in the Czech Republic, even in comparison with ungrazed areas, and it was concluded that cattle
were of little value for the restoration of species rich grasslands in this circumstance (Mate
ˇ
jková
et al
., 2003).
Indicative stocking densities for different types of acid grassland (NVC types U1–6) are given in the Upland
Management Handbook (English Nature, 2001):
unimproved upland grassland with more than 50%
Agrostis–Festuca
grassland: 5 sheep/ha or 0.75
cattle/ha or 0.5–0.75 LUs/ha all year, or equivalent during the summer only (Countryside Council for
Wales, 1992);
unimproved upland grassland with less than 50%
Agrostis–Festuca
grassland (ie
Molinia-
or
Nardus-
dominated): 2.5 sheep/ha or 0.5 cattle/ha all year or 3.7 LUs/ha or equivalent during the summer
only. (Countryside Council for Wales, 1992);
stocking should not normally exceed 0.25–0.6 LU/ha on upland rough grazing pastures.
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However, it must be stressed that these indicative stocking densities are only a guide. The appropriate
stocking density will be determined by, amongst other things, the management objectives, the site (location,
soil type, altitude, aspect) and weather.
Virtually all sub-montane grasslands require some mechanism to prevent succession to shrubs and woodland
if they are to remain as grassland. Where the grassland is of value for wildlife halting this succession is
obviously desirable although the presence of some trees and scrub can increase biodiversity. At low stocking
densities, grazing will tend to produce a mosaic of tall and short vegetation, especially on larger areas.
High stocking rates are more likely to create a uniformly short turf with few flowers (Ausden and Treweek,
1995). Winter grazing can prevent the build-up of dead vegetation and arrest succession, but still allow
plants to flower and set seed. Many areas of species-poor grassland have been derived from heavy grazing
of dwarf-shrub communities. Conservation objectives for some upland areas may, therefore, focus on the
restoration of an upland heath resource rather than the maintenance of a species-poor grassland community.
Summary
Grazing by sheep alone can lead to
Nardus
and
Molinia
becoming dominant. Cattle will graze both these
plant species to a greater extent than sheep and this may reduce their dominance and result in greater
botanical diversity. Mixed grazing by cattle and sheep has been shown to be effective in reducing the
dominance of
Nardus
and results in increased sheep performance.
Best practice
Acid grassland with more than 50%
Agrostis–Festuca
can be grazed with 5 sheep/ha or 0.75 cattle/ha
all year, or equivalent during the summer only.
Grazing by cattle can be used to reduce the dominance of tussock-forming grasses such as
Nardus
stricta
and
Molinia caerulea
. Acid grassland with less than 50%
Agrostis–Festuca
(ie
Molinia-
or
Nardus-
dominated) can be grazed with 2.5 sheep/ha or 0.5 cattle/ha all year or 3.7 LUs/ha or equivalent
during the summer only.
Mixed grazing with cattle and sheep can result in increased sheep performance. To be effective the
stocking density of the cattle should be about 0.5–1.0 cattle/ha, depending on the cover of
Nardus
and
Molinia
, during June and July.
Productive cattle eg lactating beef cows and their calves may have to be removed by early August from
Nardus
and
Molinia
grassland if animal performance is not to suffer. Dry stock may be used outwith the
growing season of these plant species.
3.4 Periodically flooded grasslands
There is no specific information on the effects of grazing by cattle on periodically flooded grasslands.
An experimental study on
Cynosurus cristatus–Centaurea nigra
(MG5) and
Cynosurus cristatus–Caltha palustris
(MG8) grasslands on the Somerset Levels (Mountford
et al
., 1993; Kirkham
et al
., 1996) on the effects
of fertilization used cattle to graze aftermaths after cutting for hay, but there is no information on the effects
of the grazing by cattle
per se
.
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3.5 Coastal grasslands including cliff-tops
The vegetation of maritime cliffs is dependent on the access of grazing animals. Grazing of
Festuca rubra
Armeria maritima
(MC8) maritime grassland shifts the composition to the
Plantago coronopus
sub-community
at the expense of the others (Rodwell, 2000). Grazing is also responsible for the characteristic short sward
of the
Festuca rubra–Plantago
spp. (MC10) maritime grassland, and the predominance of this community at
the expense of
Festuca rubra–Holcus lanatus
(MC9) maritime grassland in areas where the vegetation is
grazed.
Replacement of sheep by cattle would reduce the impacts of grazing on most cliff communities, as the
proportion of the vegetation accessible to grazing would fall.
One bird particularly associated with coastal grassland is the chough. They require grassland management
that produces medium-high grass sward height during June–September and short, open swards between
January and May. The reduced grazing in the summer produces good conditions for Tipulid egg laying,
whilst short swards in the winter allow effective searching by the choughs (Bignal
et al
., 1996). Locally this
could conflict with requirements to keep the vegetation in optimal condition.
Summary
There is no specific information on cattle grazing, although it could be implied that some areas will not be
accessible to cattle.
Best practice
Replacement of sheep by cattle may lead to greater diversity by reducing grazing in more inaccessible
areas. Where chough are present, grazing should be manipulated to produce medium-high grass sward
heights during June–September and short, open swards between January and May.
3.6 Machair
Machair is traditionally managed in one of two ways; rotational cropping or permanent pasture. In general,
the flatter, accessible areas are managed by arable cropping with a crop of traditional varieties of oats,
barley and rye being taken for two years with the aid of seaweed fertiliser and then the area is left fallow
for two years to allow fertility and soil organic matter to build up again. These areas are usually winter
grazed. However, in recent years a greater number of townships have fenced the machair, either into
individual holdings or larger areas, which allows the possibility of grazing the fallow areas in summer.
Areas where ploughing is not possible have tended to be used as permanent pasture (Love, 2003).
In both situations the vegetation is typically described as
Festuca rubra–Galium verum
fixed dune grassland
(MC8). Grazing is accepted as maintaining the diversity of machair vegetation through its removal of taller
growing species, provision of regeneration niches through trampling and the opening of the vegetation to
allow the growth of mosses. Late summer or winter grazing breaks up rank vegetation and allows the
flowering/seed set of many plants (D. Beaumont,
pers. comm.
). This is particularly important for corncrake
which require ungrazed cover vegetation from February–October, adjacent to areas of grassland without
grazing from March/April–August. Grazing levels are set within the township and generally reflect long-term
sustainable levels.
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However, the impact of summer grazing on the diversity of the characteristic fallow flora is unknown, as is
the effect of continuing replacement of cattle by sheep as the main grazing animal. This is in part due to the
ageing crofter population switching to an easier care system, as well as younger crofters doing the same in
response to a need to earn more off-croft income as a result of depressed agricultural incomes. However,
cattle are the foundation of the ‘traditional‘ cultivation system of the machair since the cereals are grown only
for cattle feed. Without continuing cultivation a range of bird species would probably suffer (corncrake, corn
bunting, twite, ringed plover – J. Wilson,
pers. comm.
).
For other dune grasslands, reduced grazing can lead to the replacement of open
Ammophila arenaria–
Festuca rubra
semi-fixed dune (SD7) by the ranker
Ammophila arenaria–Arrhenatherum elatius
grassland
(SD9) (Rodwell, 2000), and grazing has been put forward as the best means of management to prevent
the dominance of a few tall grasses in dune vegetation (Kooijmann and van der Meulen, 1996). Absence
of grazing in calcareous dune communities results in tall vegetation with a spider fauna made up of only
common species. Heavily cattle-grazed areas contained a number of rarer species, but diversity and the
presence of rare species was promoted by heterogeneity in the vegetation and the presence of transitional
areas between short and tall vegetation (Bonte
et al
., 2000). This suggests that moderate grazing, that
produces this heterogeneity, is likely to be optimal at providing the correct habitat structure for spiders in
these habitats.
Summary
Traditionally, machair areas have been grazed by cattle. The exact impact of replacement of cattle by sheep
is not known, but it can be implied that grazing by sheep rather than cattle may result in less structural
heterogeneity in the swards.
Best practice
Winter grazing with cattle at moderate (<0.5 LU/ha) stocking densities on cropped areas will enhance
soil fertility.
Moderate (<0.5 LU/ha) grazing of pasture areas in summer is likely to lead to the greatest heterogeneity
in habitat.
3.7 Rush pasture
This section deals with rush pasture, purple moor grass and rush pasture and
Juncus–Festuca
grassland.
In South-West Scotland,
Molinia–Juncus
occurs in a natural state and is an important habitat in its own right
(centered on NVC class M23
Juncus effusus/acutiflorus–Galium palustre
rush pasture). The UK Biodiversity
Action Plan states that no area estimates are available for Scotland, but the total extent is thought likely to
be in the region of 2,000ha (www
.ukbap.org.uk). However this may be an underestimate as MacIntosh
(unpublished) reports that the total area of NVC types M10, M22, M23, M25 and M26 is in the region
of 8000ha.
It is estimated that the Stewartry ESA covers one of the main concentrations of purple moor grass and rush
pasture in the country (purple moor grass and rush pastures Habitat Action Plan; UK Biodiversity Action Plan,
http://www
.ukbap.org.uk). Key plant species associated with purple moor grass and rush pastures include:
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wavy St. Johns-wort
Hypericum undulatum
, whorled caraway
Carum verticillatum
, meadow thistle
Cirsium
dissectum
, marsh hawk’s beard
Crepis paludosa
, greater butterfly orchid
Platanthera chlorantha
and lesser
butterfly orchid
Platanthera bifolia
. These purple moor grass and rush pastures are a priority for nature
conservation because they are highly susceptible to agricultural modification and reclamation, afforestation,
scrub encroachment under light or no grazing, or loss of floristic species through overgrazing and too
frequent burning. Little specific information is available on the role of cattle grazing in the historic
degradation or conservation management of this habitat. The Upland Management Handbook provides
information on the role of cattle in conservation management (English Nature, 2001). It is recommended on
NVC types M17, M22, M23, M24 and M26 to use light spring/summer grazing by cattle (although ‘light
grazing‘ is not defined), increasing the stocking density in late summer/autumn to allow the flowering of
species-rich communities. In
Molinia
-dominated areas, a relatively high grazing intensity (the equivalent of
one cow/ha) may be necessary to reduce the dominance of
Molinia
, preferably with cattle, during the
period of maximum growth and palatability of
Molinia
, ie, mid-May to mid-July. Kirkham
et al
. (2003) found
that on lowland sites with purple moor grass and rush pastures, mainly in the SW of England, actual stocking
densities were about 0.4 LU/ha annually.
The
Juncus squarrosus–Festuca ovina
grassland (U6) is strongly encouraged by particular kinds of burning
and grazing treatments on blanket bog. Once established,
Juncus squarrosus
can be persistent and invasive,
but it can decline due to competition from
Sphagnum
or taller vegetation if grazing is reduced or removed.
Cattle readily graze rushes
Juncus
spp., especially later in the summer when grass species die back
(Grant
et al
., 1985) and at moderately high stocking levels can significantly reduce their extent in a field.
They will graze sharp-flowered rush
Juncus acutiflorus
in preference to soft rush
J. effusus
and compact rush
J. conglomeratus
and this can lead to the replacement of the former by soft rush in some circumstances.
Summary
Without cattle, the
Molinia
in
Molinia–Juncus
pastures may become very dominant, as sheep tend not to
graze
Molinia
(Grant
et al
., 1985). Cattle will also graze
Juncus
spp., especially in late summer.
Best practice
Cattle may graze rush pasture lightly (0.25 LU/ha) in spring and early summer prior to the flowering of
a number of species. Thereafter stocking density may be increased in late summer/autumn.
Rush dominance in
Juncus–Festuca
grassland may be reduced by grazing with cattle in late summer/autumn.
3.8 Lowland heath
Rodwell (1991) describes six lowland heath communities but these are mainly distributed across England
and into North Wales. In Scotland, sub-montane heaths are more widespread. They are distributed on free-
drained, acidic soils of hill slopes and include the
Calluna vulgaris–Arctostaphylos uva-ursi
heath (H16) in
the Grampian hills and
Calluna vulgaris–Vaccinium myrtillus–Sphagnum capillifolium
heath (H21) of the far
north of Scotland (Rodwell, 1991).
Light summer grazing was associated with successful wildlife populations on lowland heaths, but is only one
tool in heathland management (Bacon, 1998). Cattle suppress birch scrub and reduce the competitive
dominance of grass species and encourage a greater diversity and structure of vegetation. Trampling serves
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to incorporate litter and create pockets of bare ground that facilitates seed germination and recruitment.
Bracken invasion can be countered through the trampling disturbance of cattle compared with smaller
herbivores. However, as for moorlands, the stocking densities must be carefully monitored because there is
a substantial risk of dieback to heather and later colonization by opportunistic grass species. Grazing is an
essential part of the management of lowland heaths but has become less common in recent decades and
this has led to scrub or bracken encroachment. Grazing with cattle is a cost-effective means of managing
lowland heaths and for the maintenance of a balance between scrub (desirable for wildlife in small patches
within heathland) and
Calluna
in its various developmental phases, and for the suppression of bracken
(Sutherland and Hill, 1995).
Summary
Grazing by cattle may be more effective at maintaining diversity of plant species. Trampling by cattle may
create niches for seed germination and help to control the spread off bracken.
Best practice
Grazing by cattle in summer at a light (eg 0.5 LU/ha) stocking rate will suppress undesirable species
and achieve a balance of scrub and dwarf shrub species.
3.9 Moorland
Moorlands are composed of a mosaic of plant communities, such as heath, grass and mire, dependent on
climate, altitude and geographic location. Moorland can be dominated by dwarf shrub, mainly H10, H12,
H13, H14, H19, H20 and H21, all NVC classes that include
Calluna vulgaris
, and/or indigenous grasses
(where dominant representing U1, U4, U5 and U6 acid grasslands described elsewhere) (Rodwell, 1991;
1992). Grasslands have most frequently replaced heather as a result of degradation related to recent
increased stocking densities of livestock, combined with overly frequent burning (UK Biodiversity Action Plan;
English Nature, 2001; Hester, 1996). Such grass, rush and sedge communities are of a lower nature
conservation value than the dwarf shrub communities they replace (Welch and Scott, 1995).
Heather and other dwarf shrubs are less preferred by grazing livestock than grasses but are eaten
by livestock when there is nothing else available to consume (English Nature, 2001). Heather decline does
not happen instantly because it has energy reserves in the roots to replace the current year‘s shoots that
are eaten. Studies in the Peak District, England have shown that 36% of the heather cover in 1913 is
now dominated by grasses (Anderson and Yalden, 1981). A similar change was observed in Cumbria,
where aerial photographs have indicated that 70% of heather-dominated vegetation of 1946 has been
replaced by vegetation dominated by grasses (Nature Conservancy Council, 1987). Dependent on local
edaphic and climatic conditions, heather may have been replaced by
Festuca ovina–Agrostis capillaris–
Galium saxatile
grassland (U4) (Welch, 1974) on drier soils or by
Nardus stricta–Galium saxatile
(U5) on
the more species rich and dry sites and
Molinia caerulea–Potentilla erecta
mire (M25) and
Juncus squarrosus–
Festuca ovina
grassland (U6) on the wetter soils (Rodwell, 1991; 1992).
Cattle can be part of the problem of habitat degradation in the uplands, but at moderate to low stocking
densities, cattle have been shown to be effective in restoring upland habitats. Cattle have a greater ability
than sheep to digest poor quality forage (Armstrong, 1996) and as a result they are more likely to forage
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amongst mat-grass or purple moor-grass in summer. Cattle have been successfully used to reverse
the expansion of purple moor grass and to restore
Calluna vulgaris
on Marsden Moor, Derbyshire
(http://www
.whitebredshorthorn.com/bluegrey/marsdenmoor.html). Cattle are also effective at trampling
tall, coarse vegetation such as bracken and scrub and are effective at opening up uniform, dense vegetation
for habitat restoration (English Nature, 2001). The Upland Management Handbook provides a comprehensive
review of general effects of changes to grazing management for different situations and conservation
objectives. There is little specific mention of the role of cattle in grazing management on moorlands but cattle
are cited mainly as a tool for remediation where moorland has been degraded to
Molinia
- and
Nardus
-
dominated grassland. The plants and animals typically associated with heather moorland are generally of
greater nature conservation value than those associated with the acid grassland or bracken,
Pteridium
aquilinum–Galium saxatile
(U20) communities which replaces them (Evans and Felton, 1987).
Heather growth is characterized by architectural changes that have been classified into pioneer, building,
mature and degenerate phases, each larger and with a larger proportion of wood content than the previous
phase (MacDonald, 1996). Each phase lasts about 5–10 years but heather grows most rapidly in the
building phase and reaches its maximum cover and density during this phase. Low intensity grazing can
slow down the rate at which heather ages, keeping more plants in the building, rather than degenerate
phase, of growth (Gimingham, 1995; Mowforth and Sydes, 1989). In this way grazing can decrease the
frequency with which burning or cutting is used to manage heather moorland. Too much grazing can lead
to the loss of heather cover (Hester, 1996) because it will generally decline if grazing animals utilise more
than 40% of the season‘s growth (Grant
et al
., 1982). A secondary effect of excessive grazing is the loss
of representation of each growth phase. Heather is most vulnerable to cattle grazing in the autumn (when
energy reserves are low after flowering and seed set) and spring (after the first flush of growth), and winter
grazing should be avoided altogether (Mowforth and Sydes, 1989). Grazing effects on heather tend to be
lower in summer when cattle graze other more nutritious and abundant herbage.
Calluna vulgaris
is killed
by trampling, urine enrichment and smothering by dung pats (Dennis, 1999). Supplementary feeding of
cattle should be avoided throughout the year on any heather moorland because this would attract livestock
to dry heath, wet heath and blanket bog in the moorland mosaic, all intolerant of treading damage.
Poaching from treading of hooves can lead to the formation of bare ground, tracks, ruts and more general
erosion. Likewise, water troughs should be located in areas of low conservation interest, such as in acid
grassland parts of moorland. Nutrient enrichment can result from dung and supplementary feed incorporation
into the soil, with consequences for local vegetation. Cattle dung is an important resource for beetles and
flies which, in turn, provide food for birds.
If grazing pressure is kept relatively low, heather and other plants mature and this can result in a patchy
structure to the vegetation (Gimingham, 1972). As patches of heather reach this degenerate stage, bracken
or calcifugous grasses can replace heather in the open patches (Rodwell, 1992). However heather can also
regenerate vegetatively by the growth of adventitious roots on stems to produce stable stands of heather
(MacDonald
et al
., 1995). Where restoration of
Calluna
is the management objective for a site, the current
botanical composition can strongly influence the response of the vegetation to changes in stocking densities
of livestock, although most studies have focused upon sheep. A cessation of grazing on moorlands where
heather was already present in the vegetation led to an increase in its cover at a rate of up to 0–5% per year
(English Nature, 2001). Without heather, tall grass, scrub and woodland vegetation communities developed
on such moorland sites (Hester, 1996; Ward
et al
., 1995), dependent on factors such as initial floristic
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composition, proximity to seed source, extent of soil disturbance and niche availability (Milne
et al
., 1998).
Grazing on other shrubs, eg,
Vaccinium myrtillus
, occurs mainly in September and October but it is more
tolerant of grazing than heather. Moderate levels of grazing may lead to a change in dominance from
heather to bilberry (Welch
et al
., 1994).
The numbers of sheep and wild herbivores such as red deer must be taken into account when planning
stocking densities of cattle for grazing heather moorland. An assessment of grazing pressure on moorland
may be necessary using the ‘Grazing Index‘ (English Nature, 2001; MacDonald
et al
., 1998). The Grazing
Index is calculated as the proportion of shoots with evidence of grazing. Great care must be taken in its
interpretation as the relationship between the Grazing Index and level of offtake is not linear. At high levels
of offtake the Grazing Index is insensitive. Also it does not allow comparison between grazing caused by
different herbivores, so that a tip removed by a red grouse equates to the same level of damage as a shoot
bitten back into the previous year‘s growth by a cow. The timing of grazing management can be modified
to promote the recovery of degraded heaths and mires; cattle or other livestock can be removed from the
management unit at the end of September and their return delayed until June. Stocking densities should not
culminate in excessive poaching or other indicators of overgrazing such as an increase in the area of bare
ground (MacDonald, 1993). Annual stocking rates on dry heath (NVC types: H4, H8, H9, H10, H12,
H15, H16, H17, H18, H21) should never exceed 0.075–0.225 LU ha
–1
(Edwards and Marsden, 1991).
Increased altitude and soil wetness would further reduce the potential annual stocking density that could be
sustained. Heather recovery is possible if grazing is reduced to c. 0.8–0.9 sheep/ha/yr on degraded dry
heath (Pakeman
et al
., 2003) and to c. 0.7 sheep/ha/yr on degraded wet heath (Hulme
et al
., 2002).
Summary
Cattle are not necessary for the effective management of heather moorland and excessive grazing by cattle
will damage heather plants. On areas where the moorland has been degrade by ingression of
Nardus
or
Molinia
, grazing by cattle may help to reduce the dominance of these species.
Best practice
Avoid supplementary feeding of cattle on heather moorland.
Remove cattle from heather moorland in winter.
Light grazing (0.075–0.225 LU/ha/year) of heather by cattle can be tolerated, but stocking densities
must be set to avoid high levels of utilisation. Actual stocking densities of cattle must take account of the
presence of other species of herbivores such as sheep or deer.
3.10 Lowland raised bog
Lowland raised bogs are peatland ecosystems which develop in lowland areas such as the head of
estuaries, along river flood-plains and in topographic depressions. Anaerobic conditions prevail from the
waterlogged state and this slows down the decomposition of plant material and leads to the accumulation
of peat that elevates the bog surface. A dome of peat of up to 12m thickness can accumulate that separates
the bog surface from the water table, so that it forms an ‘ombrotrophic‘ (or ‘rain-fed‘) bog. The surface is
typically waterlogged, acidic and deficient in plant nutrients and gives rise to a depauperate but distinctive,
specialised plant assemblage. The spongy surface is characterized by the
Sphagnum
mosses that lead to
the development of peat and a surface mosaic of pools, hummocks and lawns which support different
species assemblages.
Sphagnum
also retains water through dry periods and keeps the bog surface wet.
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The plant assemblages include the bog pool communities M1–M3 and M18 E
rica tetralix–Sphagnum
papillosum
raised and blanket mire. As elsewhere across the UK and north-west Europe, the area of lowland
raised bog has declined considerably since the early nineteenth century. The area of lowland raised bog in
Scotland retaining a largely undisturbed surface is estimated to have diminished from an original
28,000–2,500ha (UK Biodiversity Action Plan). The historic causes of loss and degradation have been
agricultural intensification, afforestation and commercial peat extraction. Threats to remaining areas of
lowland raised bog are more likely to be drainage and general lowering of groundwater tables. Such
disturbances, including peat cutting can result in the development of
Scirpus cespitosus–Erica tetralix
(M15)
wet heath,
Calluna vulgaris–Eriophorum vaginatum
blanket mire (M19),
Eriophorum vaginatum
blanket and
raised mire (M20) and
Molinia caerulea–Potentilla erecta
mire (M25).
Grazing is rarely the primary cause of degradation of lowland raised bogs and there is little mention in
the literature of the role of cattle in managing this habitat. Cattle grazing may be an additional factor
after drainage and lowering of the water table have dried out the site and allowed access to grazers.
On the drier fringe of the habitat, natural succession may lead to scrub and tree growth (
Betula pubescens–
Molinia caerulea
woodland, M4) and grazing cattle may have a role in suppressing growth of these species
to maintain the higher valued bog plants.
Summary
There is little specific mention of grazing by cattle in the literature.
Best practice
Avoid grazing by cattle, except on the drier fringes to suppress scrub.
3.11 Blanket bog
Blanket bog or wet mire is waterlogged, composed of deep peat soils and has a low annual productivity
in vegetation growth (Coulson
et al
., 1992). Wet heath is the most productive, as a transition between
blanket bog and
Calluna
-dominated dry moorland. Blanket bog vegetation has lower digestibility and
mineral content than similar vegetation on mineral soils. The peat of blanket mires is constantly leached by
rain, is low in available nutrients, and is generally too deep to allow root penetration to the underlying
mineral soil (English Nature, 2001). The biotope is characterized by a ground layer of sphagna and a low
canopy of ericoid shrubs (
Calluna vulgaris
and
Erica tetralix
) and graminoids (
Eriophorum vaginatum,
Scirpus cespitosus
and
Molinia caerulea
) in various proportions representing NVC classes M15–M20
(Rodwell, 1991). The wetter the site the lower the productivity of the blanket mire plants and the greater the
sensitivity to grazing. Long-term grazing of sheep and burning of mire communities has lead to the
replacement of the sphagna and ericoid shrubs by grasses and cotton-grass
Eriophorum
spp.-dominated
communities in many areas (Ratcliffe, 1959; Rawes and Williams, 1973; Tansley, 1939; Miles, 1988;
Felton and Marsden, 1990; Rodwell, 1991; Thompson and Miles, 1995).
There is a dilemma concerning a role for cattle grazing in these biotopes. Cattle are not suitable for wet
bog because of the substantial damage caused by poaching by these heavy grazing animals (Spedding,
1971). The dilemma arises from the high proportion of
Molinia
in these biotopes, a grass species that is
not consumed by sheep. Thus, cattle may have a role in summer in reducing the extent of
Molinia
because
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they will readily consume this species where available, in preference to the typical blanket bog species of
Calluna
,
Erica
sp. and
Empetrum
sp. (Grant
et al
., 1987). Cattle also consume more dead components of
vegetation than sheep and reduce litter and open up the soil for new growth. In the absence of enough
grass, cattle have a detrimental effect on
Calluna
by biting more of the shoot length than sheep.
In conclusion, Grant
et al
. (1987) recommended that cattle should not graze where
Calluna
is dominant on
blanket bog but that they may be a useful means of reducing undesirable grass species on wet moorland
and blanket bog composed of a mixed vegetation cover. The Upland Management Handbook (English
Nature, 2001) provides a comprehensive review of grazing interactions with blanket peat, blanket bog and
wet heath, although most information relates to grazing by sheep only. Some recommendations are given
that are pertinent to cattle grazing:
undisturbed wet heaths and blanket mires require little management and should be left completely alone
as far as possible;
if bare peat is exposed, it is very difficult to stabilise and any stocking will make matters worse;
there should be no grazing in the autumn or winter, with at most very light grazing in the summer,
as the ideal grazing regime for wildlife on most wet heaths and blanket mires;
all cattle should be removed in winter, but it is preferable to remove all livestock in winter.
Summary
Generally blanket bog should not be grazed by cattle. The exception is where the bog has been degraded
by ingression of
Molinia
.
Best practice
Do not graze
Calluna
-dominated blanket bog by cattle.
Light grazing (eg two cattle/ha for short periods of a few weeks in early summer) of blanket bog of
mixed vegetation in summer by cattle may reduce dominance of
Molinia
.
Remove cattle in autumn and winter.
3.12 Semi-natural woodland
Few quantitative studies have been undertaken on cattle grazing in woodlands. Recently, the Forestry
Commission has reviewed cattle grazing in British woodlands based on surveys of current grazing practices
(Mayle, 1999; Armstrong
et al
., 2003; Armstrong and Bullock, 2003). The field layer of woodlands is
composed of typical grassland, heath or moorland vegetation and the foraging patterns and effects of cattle
are very similar to those observed for these vegetation types in open habitats (refer to corresponding
sections). Grazing by cattle in woodlands can lead to reductions in bracken and
Agrostis
sp. and lead
to colonization by wavy hair grass (
Descampsia flexuosa
) and creeping-soft grass (
Holcus lanatus
)
(Rodwell, 1991). Poaching by cattle also encourages the colonization of creeping-soft grass but has also
been observed to mechanically remove moss mats from boulders and thus reduce abundance of these plants
(Mountford
et al
., 2000). The major difference in the woodland context is the availability of bark or browse
on low branches of mature trees, or of regenerating trees and shrubs as a supplement of forage to that
normally available in the field layer. Continuous or winter access of cattle to woodlands can cause significant
reductions in the density of saplings (eg, Wistman‘s Wood on Dartmoor; Mountford
et al
., 2000). In this
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study cattle grazing led to a reduced density of oak saplings and the absence of rowan and holly (palatable
species). There have been numerous anecdotal accounts of damage to woodland flora caused by high
stocking densities of cattle in Scottish woodlands (Dennis, 1999).
Armstrong
et al
. (2003) surveyed UK woodlands grazed by cattle and found several differences in the
purpose of cattle grazing in woodlands in Scotland compared with England and Wales. In Scotland, most
sites were in private ownership and were grazed with commercial breeds for cattle production, often being
used for winter shelter. This was a substantial contrast with the situation in England and Wales, where many
woods were managed by conservation agencies or conservation NGOs, using traditional breeds and with
low stocking densities in summer only to realize nature conservation objectives. Little information was
provided on seasonal effects of cattle grazing but a study on Rum was cited (Armstrong
et al
., 2003) in
which deciduous trees were browsed more in summer than winter while in winter seedlings of Scot‘s pine
were preferentially taken (Scoggins, 1999). The main objective of the study was to reduce the cover of
Molinia caerulea
, open up the vegetation and to allow natural regeneration of trees. There was no particular
stocking density used to achieve tree regeneration within UK woodlands, although stocking densities higher
than 0.1 cattle/ha/year reduced even poor levels of regeneration (Armstrong
et al
., 2003). By their
trampling, cattle are thought to create regeneration niches for trees (Dennis, 1999). Hence, an increased
number of trees germinating may offset the mortality of young trees caused by cattle browsing.
High browsing intensity is indicated by evidence of browsing damage to hawthorn and holly. By contrast,
evidence of only light browsing on oak, goat willow or birch saplings would suggest overall light browsing
intensity (Armstrong
et al
., 2003). In conclusion, this survey showed that conservation managers were
content that cattle grazing achieved their conservation objective for the woodlands, and these were
summarized as follows:
1 to benefit biodiversity generally by:
reducing tree/scrub regeneration;
reducing the existing shrub layer;
maintaining open habitats;
reducing dominant plant species.
2 to benefit individual species or groups;
3 to encourage tree regeneration.
Cattle can also maintain the structural and botanical diversity of riparian vegetation within coniferous
plantations by reducing the competitive dominance of
Juncus
rush, calcareous flush vegetation and
Agrostis–
Festuca
grasses that would otherwise prevail without grazing (Humphrey and Patterson, 2000). It was concluded
that habitat quality could be maintained as long as the riparian areas were of sufficient length to avoid
localized trampling effects on vegetation. The nine years of experimental grazing failed to increase the
frequency of rare herbs in these habitats.
Summary
Limited studies suggest that grazing by cattle can create more niches for the regeneration of saplings.
However significant damage can occur if grazing pressure is too high, especially in winter.
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Best practice
Avoid grazing by cattle in woodlands in winter as significant damage to saplings can occur.
Light grazing in summer at (<0.1 cattle/ha) can increase biodiversity by maintaining open habitats,
creating re-generation niches alongside water courses running through forestry.
3.13 Wood pasture
Wood pasture represents the extreme of woodland grazing where widely spaced, pollarded or individually
fenced trees remain in an otherwise open pasture context. Such pastures are characterized by the complete
absence of the botanical species composition and structural patchiness that would be associated with semi-
natural woodland (Kirby, 1992). The field layer will therefore most often represent mesotrophic grassland
and cattle grazing effects on this habitat are reviewed under neutral grasslands. The most valued part of this
type of pasture is the old age of the trees. Such ‘veteran‘ trees have important standing deadwood
components and are extremely important habitats because this age class of trees is often absent from
managed woodlands. Such trees support saproxylic insects, saprophytic fungi and epiphytic lichens and
bryophytes. The main concern for these trees is potential ring-barking from livestock having close access to
them, and the lack of replacement and slow disappearance of these trees from wood pastures.
Summary
No specific information on cattle grazing.
Best practice
Old trees may need to be protected from ring barking and rubbing.
3.14 Wetland
Management issues related to wetlands are broadly similar to fen, in that continued traditional mowing is
the most appropriate management to maintain species richness in most situations, but cattle grazing can be
a substitute (Gander
et al
., 2003). However, cattle grazing results in redistribution of nutrients and hence
eutrophication of resting areas and cattle avoid species such as
Cladium mariscus
such that it might spread
at the expense of other species.
Summary
Mowing is the preferred management, but grazing by cattle can substitute.
Best practice
Grazing by cattle can substitute for mowing. However no research has quantified the appropriate levels
for different objectives.
3.15 Fen
Management of some form (burning, grazing or mowing) is necessary to prevent succession of this habitat
to scrub and woodland (Vinther and Hald, 2000). This has been noted for a range of fen communities such
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as
Pinguiculo–Caricetum dioicae
(M10) and
Carici–Saxifragetum aizoides
(M11) mire (Rodwell, 1991).
It is also important for maintaining the characteristic vegetation of fen meadow communities such as
Juncus
subnodulosus–Cirsium palustre
(M22) fen meadow,
Juncus effusus/acutiflorus–Galium palustre
rush pasture
(M23) and
Cirsio–Molinietum caeruleae
fen meadow (M24). Grazing has also been noted to prevent the
succession of swamp communities to woodland, such as
Glyceria fluitans
(S22) water margin vegetation,
Carex rostrata–Potentilla palustris
tall herb fen and
Phalaris arundinacea
tall herb fen (S28) (Rodwell, 1994).
It has been suggested in recent years that extensive grazing is the best method of managing fen vegetation
(Tolhurst, 1997). However, one of the main conclusions of this report was that further research was necessary
to match breed and management strategy to site conditions. The report also suggested that cattle and ponies
would often be preferable to sheep as they can provide structural diversity, poach areas, browse on scrub
and avoid flowering heads of species such as orchids.
A comparison of light cattle grazing (average of 0.4 livestock units/ha) with ungrazed fen (Ausden
et al
.,
2005) showed that grazing reduced the dominance of
Phragmites australis
, increased stem densities of
Glyceria maxima
, and increased the plant-species richness of grazed areas. The shift from
Phragmites
to
Glyceria
is similar to that in other studies of fen grazing and in studies of the effects of summer grazing
(summarized in Ausden
et al
., 2005). However, in this study, grazing was detrimental to the rare snail
Vertigo moulinsiana
. The conclusions of this study were that light grazing with an appropriate cattle breed
was a useful method of increasing plant species richness and habitat heterogeneity. However if grazing
pressure was too high ungrazed areas suitable for
V. moulinsiana
would not be left. Also, cattle lose condition
in the winter on this vegetation, so grazing of this habitat needs integration with other sources of winter fodder.
A study in southern Germany contrasted cattle grazing with mowing (Stammel
et al
., 2003). They concluded
that mowing was the most appropriate method to maintain a high species richness, but that grazing could
be recommended as an alternative if the other option was abandonment.
Grazing and mowing have also been used to restore scrub-dominated, former fen vegetation. This re-instatement
of management increased species richness and reduced the dominance of woody species. Grazing resulted
in a greater dominance of rush or sedge species, whilst mowing increased the dominance of grasses
(Vinther and Hald, 2000).
There is no study that contrasts the effects of cattle with other livestock types. Traditional mowing of fen
vegetation is the preferred method of maintaining high species richness, but light grazing with cattle is an
acceptable alternative.
Summary
Mowing is currently the preferred management for fen, but grazing by cattle can substitute. It has been
suggested that cattle (or ponies) are preferable to sheep as they can provide structural diversity, poach areas,
browse on scrub and avoid flowering heads of species such as orchids.
Best practice
Mowing is the preferred management regime for fen vegetation.
Light grazing by cattle in summer (<0.4 cattle/ha) may be used as an alternative to mowing.
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3.16 Coastal heath
This vegetation is found on a wide variety of moderately base-poor soils on the less exposed parts of
maritime cliffs (
Calluna vulgaris–Scilla verna
heath (H7), Rodwell, 1991). The dwarf-shrub canopy is often
open, allowing grassy swards with many herbs to form between bushes. Grazing regulates the density and
height of the dwarf shrub component, but also prevents succession to scrub. Where heavily grazed the
rosette hemicryptophytes
Plantago lanceolata
and
P. maritima
can dominate. It is claimed that cattle grazing
gives a less close cropping to this vegetation and hence a greater heterogeneity to the sward (Rodwell,
1991). There is no experimental work on coastal heaths. Best practice should follow that of lowland heath.
Summary
Grazing by cattle may be more effective at maintaining diversity of plant species, but grazing is necessary
to prevent scrub encroachment.
Best practice
Grazing levels should be set to prevent suppression of dwarf shrubs but to maintain a high proportion
of forbs in the sward. However, no research has quantified the appropriate grazing regimes for coastal
heath, and grazing regimes would have to take into account the relative proportions of dwarf-shrub and
herbaceous vegetation and any specific requirements of species present.
3.17 Saltmarsh
Saltmarsh in Scotland covers the following NVC classes: SM 1–2, 6, 8, 10, 13–20, 23, 28. The UKBAP
(http://www
.ukbap.org.uk/UKPlans.aspx?ID=33) states that ‘grazing has a marked effect on the structure
and composition of saltmarsh vegetation by reducing the height of the vegetation and the diversity of plant
and invertebrate species‘. However, this appears at odds with other conclusions that moderate grazing
increased plant diversity as it prevents the dominance of rank grasses, and only at high grazing intensities
does it reduce diversity. This has been shown for a range of situations on saltmarshes both where grazing
has been removed or where it has been reinstated following removal (eg Bakker
et al
., 1997; Olff
et al
., 1997;
Bouchard
et al
., 2003). For instance on
Puccinellietum maritimae
(SM13) salt marsh, grazing maintains the
dominance of the perennial grasses
Puccinelia maritime
and
Festuca rubra
, and at heavier grazing levels
species such as
Halimione portulacoides
and
Limonium
spp. are reduced in abundance (Boorman, 1967).
The effects of grazing are to:
retard the process of sedimentation;
reduce the species richness of lower marsh at high stocking rates;
increase the abundance of lower marsh species in the upper marsh, and their invertebrate assemblages;
increase habitat heterogeneity;
decrease litter and detritivore populations;
decrease immigration of higher marsh animals into lower marsh;
decrease species-richness of plant feeding insects.
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Conversely, abandonment reverses the above effects and leads to a:
decrease in plant species-richness;
decrease in the diversity of vegetation types;
loss of characteristic halophytic vegetation;
reduction in species-richness of invertebrates (Andresen
et al
., 1990).
The UKBAP goes on to say that ‘intensive grazing creates a sward attractive to wintering and passage
wildfowl and waders, whilst less intense grazing produces a tussocky structure which favours breeding
waders‘. Habitat heterogeneity has been shown to be important in increasing the diversity of wading birds
present (Milsom
et al
., 1997) and increased heterogeneity is a feature of cattle grazing rather than sheep
grazing (see Chapter 2). Moderate grazing by cattle has also been put forward as a means of maintaining
saltmarsh at a young successional stage which makes it suitable for a wider range of halophytic species and
for breeding redshank and grazing waterfowl (Esselink
et al
., 2000). Increased grazing has been shown to
be detrimental to breeding redshank (Norris
et al
., 1998).
There is little information comparing grazing by different herbivores or on the timing of stocking. Cattle grazing
may be preferable to sheep grazing due to the increase in heterogeneity it brings. Cattle grazing may allow
more shrubby species to dominate, whilst sheep grazing may shift the dominance more to grassy vegetation
(Rodwell, 2000). It has been suggested (Andresen
et al
., 1990) that a stocking rate of c. 0.5 cattle/ha is
most suitable for nature conservation purposes. However, heavy cattle trampling can lead to poaching.
Summary
No specific information on cattle grazing, but it has been suggested that cattle may lead to a more diverse flora.
Best practice
Grazing by cattle (ca. 0.5 cattle/ha) may result in more heterogeneity that grazing by sheep.
3.18 Scrub including montane scrub
In general, the presence of scrub is reduced through grazing (Hester, 1996). However, there is no published
information on the relative effects of cattle compared to other grazers. It is possible that grazing cattle may
help create regeneration niches for seedling establishment through trampling. However, they are also likely
to browse off any seedlings that emerge above the vegetation.
Browsing of montane scrub (
Juniperus communis
ssp.
Communis–Oxalis acetosella
woodland, W19 and
Salix lapponum–Luzula sylvatica
scrub, W20), particularly by sheep in the last 200 years and red deer over
recent decades, has been widely assumed to have caused a reduction in area covered by montane scrub
to the small areas in existence today (Mardon, 2000; Scottish Natural Heritage, 2003). However, complete
removal of grazing may have a long-term impact on populations of montane scrub species (
Salix
spp.,
Juniperus communis
) as a result of competition from taller growing vegetation or by the absence of
disturbance to provide new regeneration niches. Replacement of sheep or deer by cattle could be beneficial,
as cattle are less agile and hence less likely to browse scrub on steeper ground. They may also increase the
possibility of regeneration from seed by increasing the amount of disturbance and bare ground. However,
there is no specific information regarding the effect of cattle grazing on montane scrub, either in isolation or
in comparison with other species of grazer.
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Summary
No specific information on cattle grazing.
Best practice
No specific information on grazing by cattle.
3.19 Summary of impacts of grazing by cattle on habitats
Table 3.1 provides a summary of whether grazing by cattle is likely to be beneficial, neutral or detrimental
compared to grazing with other species. It should be emphasized that the information in the table is
inevitably a simplification and that the effects will depend on the specific management objectives that are
set for any particular site. It is further assumed that the grazing by cattle is carried out according to best
practice as identified in the section of the text dealing with each habitat ie that the grazing is carried out at
an appropriate stocking density and with the correct seasonal pattern. If these conditions are not met then
grazing by cattle could be very detrimental to many habitats.
Table 3.1 Summary of effects of cattle on habitats
Habitat Beneficial Neutral Detrimental Comments
Neutral grasslands No specific information
Base-rich grasslands No specific information
Acidic grasslands
Periodically flooded grasslands No specific information
Coastal grasslands including cliff-tops No specific information
Machair
Rush pasture
Lowland heath
Moorland
Lowland raised bog No specific information
Blanket bog
Semi-natural woodland
Wood pasture No specific information
Wetland
Fen
Coastal heath No specific information
Saltmarsh No specific information
Scrub, including montane scrub No specific information
For many habitats there is no specific information about the effects of grazing by cattle. For most habitats
for which there is empirical evidence, compared to grazing with other species the effects are likely to be
neutral or beneficial provided best practice is followed. Only on blanket bog when
Calluna
is dominant and
on raised lowland bog is cattle grazing always likely to be detrimental.
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4 EFFECTS OF CATTLE ON PRIORITY SPECIES
4.1 List of priority species
A list of priority animal and plant species that might be impacted by grazing associated with different
habitats is shown in Table 4.1.
Table 4.1 List of priority animal and plant species that may be affected by grazing for each
habitat (Status: P, UK Priority species; C, UK species of conservation concern;
L, Locally important species). Information from National Biodiversity Action Plans
and cross checked for Scottish distributions using Local Biodiversity Action Plans,
where available (http://www
.ukbap.org.uk)
Habitat Fauna Status
Neutral grasslands Pearl bordered fritillary
Boloria euphrosyne
P
Base-rich grasslands Mason bee
Osmia inermis
P
Mason bee
Osmia parietina
P
Ruby-tailed wasp
Chrysura hirsuta
P
Snail
Vertigo geyeri
P
Snail
Vertigo genesii
P
an Alchemilla
Alchemilla minima
P
Acidic grasslands (lowland) Pearl-bordered fritillary
Boloria euphrosyne
P
(Upland and Montane) Pearl-bordered fritillary
Boloria euphrosyne
P
Dotterel
Charadrius morinellus
L
Snow bunting
Plectrophenax nivalis
L
Purple sandpiper
Calidris maritime
L
Ptarmigan
Lagopus mutus
L
Golden eagle
Aquila chrysaetos
L
Mountain hare
Lepus timidus
L
Northern dart
Xestia alpicola alpina
C
Scotch burnet moth
Zygaena exulans subochracea
C
Mountain ringlet
Erebia epiphron
L
Thatch moss
Leptodontium gemmascens
P
Periodically flooded grasslands Lapwing
Vanellus vanellus
L
Redshank
Tringa nebularia
L
Curlew
Numenius arquata
L
Pink-footed goose
Anser brachyrhynchos
L
Coastal grasslands including cliff-tops Snow bunting
Plectrophenax nivalis
L
Small blue butterfly
Cupido minimus
L
Scottish scurvy-grass
Cochleria scotica
P
an Eyebright
Euphrasia rotundifolia
P
Dune gentian
Gentianella uliginosa
P
Juniper
Juniperis communis
P
Petalwort
Petalophyllum ralfsii
P
Matted bryum
Bryum calophyllum
P
Sea bryum
Bryum warneum
P
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Table 4.1
(continued)
Habitat Fauna Status
Machair Skylark
Alauda arvensis
P
Corncrake
Crex crex
P
Corn bunting
Miliaria calandra
C
Beetle
Protapion ryei
P
Great yellow bumble bee
Bombus distinguendus
C
Northern colletes
Colletes floralis
P
Belted beauty moth
Lycia zonaria
P
Rush pasture Marsh fritillary butterfly
Eurodryas aurinia
P
Brown hairstreak
Thecla betulae
L
Narrow-bordered bee hawkmoth
Hermaris tityus
C
Curlew
Numenius arquata
L
Snipe
Gallinago gallinago
L
Barn owl
Tyto alba
L
Scottish small-reed
Calamagrostis scotica
P
Lowland heath Twite
Carduelis flavirostris
L
(inc. Scottish upland heathland) Golden plover
Pluvialis apricaria
L
Golden eagle
Aquila chrysaetos
L
Hen harrier
Circus cyaenus
L
Merlin
Falco columbarius
L
Mountain hare
Lepus timidus
L
Scottish burnet moth
Zygaena exulans
P
Small pearl-bordered fritillary
Boloria selene
L
Large heath
Coenonympha tullia
C
Netted mountain moth
Semiothisa carbonaria
L
Broad-bordered white underwing
Anarta melanopa
L
Small dark yellow underwing
Anarta cordigera
P
Black grouse
Tetrao tetrix
P
Cranefly
Tipula (Savtshenkia) serrulifera
P
Moth
Semiothisa carbonaria
P
Moth
Xestia alpicola alpine
P
Moth
Xylena exsoleta
P
an Eyebright
Euphrasia campbelliae
P
Moorland Golden plover
Pluvialis apricaria
L
(Heather moor) Dunlin
Calidris alpine
L
Snipe
Gallinago gallinago
L
Large heath
Coenonympha tullia
L
Juniper
Juniperis communis
P
Northern prongwort
Herbertus borealis
P
Thatch moss
Leptodontium gemmascens
P
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Table 4.1
(continued)
Habitat Fauna Status
Lowland raised bog Marsh fritillary
Eurodryas aurinia
P
Small pearl-bordered fritillary
Boloria selene
L
Large heath
Coenonympha tullia
L
Reed bunting
Emberiza schoeniclus
P
Baltic bog-moss
Sphagnum balticum
P
Skye bog-moss
Sphagnum skyense
P
Blanket bog Golden plover
Pluvialis apricaria
L
Dunlin
Calidris alpine
L
Snipe
Gallinago gallinago
L
Large heath
Coenonympha tullia
L
Baltic bog-moss
Sphagnum balticum
P
Semi-natural woodland Roe deer
Capreolus capreolus
L
(Birch woodland) Badger
Meles meles
L
Cousin German moth
Paradiarsia sobrina
C
(Pine woodland) Kentish glory
Endromis versicolera
L
Song thrush
Turdus philomelos
P
Capercaillie
Tetrao urogallus
P
Scottish crossbill
Loxia scotica
P
Crested tit
Parus cristatus
L
Red squirrel
Sciurus vulgaris
P
Pine marten
Martes martes
L
Narrow-headed wood ant
Formica exsecta
P
Wood ant
Formica aquilonia
C
Wood ant
Formica lugubris
C
Cousin German moth
Paradiarsia sobrina
C
Hoverfly
Metasyrphus lapponicus
C
Hoverfly
Blera fallax
C
Juniper
Juniperis communis
P
Twinflower
Linnaea borealis
P
(Upland oak wood) Robber fly
Laphria flava
L
Spider
Dipoena torva
L
Spotted flycatcher
Muscicapa striata
C
Song thrush
Turdus philomelos
P
Redstart
Phoenicurus ochruros
L
Wood warbler
Phylloscopus sibilatrix
L
Daubenton‘s bat
Myotis daubentonii
L
Slug
Limax tenellus
L
Small cow-wheat
Melampyrum sylvaticum
P
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Table 4.1
(continued)
Habitat Fauna Status
Wood pasture Unspecified saproxylic insects
Wetland Irish lady‘s-tresses
Spiranthes romanzoffiana
P
Fen Yellow marsh saxifrage
Saxifraga hirculus
Greater water parsnip
Sium latifolium
Slender green feather-moss
Hamatocaulis vernicosus
P
Coastal heath an Eyebright
Euphrasia rotundifolia
P
Saltmarsh Unspecified rare invertebrates
Waders, gulls and terns – summer
Ducks and geese – winter
Ground beetle
Amara strenua
P
Ground beetle
Anisodactylus poeciloides
P
Natterjack toad
Bufo calamita
P
Narrow-mouth whorl snail
Vertigo angustior
P
an Eyebright
Euphrasia heslop-harisonii
P
Scrub, including montane scrub Song thrush
Turdus philomelos
P
Linnet
Carduelis cannabina
C
Yellowhammer
Emberiza citrinella
L
Dunnock
Prunella modularis
L
Whinchat
Saxicola rubetra
L
Stonechat
Saxicola torquata
L
Whitethroat
Sylvia communis
L
Broom-tip moth
Chesias rufata
L
Wooly willow
Salix lanata
P
No specific information on direct effects of cattle on priority species could be found. It is only possible to
infer potential effects through general investigations of cattle grazing and habitat quality, measured as
changes to habitat structure or floristic composition dealt with below.
4.2 Overview of effects of grazing and trampling on priority habitats
Birds
Knowledge of the effects of grazing on moorland bird populations is extremely poor and very little is
understood about how different grazing levels affect different bird species (Fuller and Gough, 1999). There are
various mechanisms by which grazing animals may influence breeding birds, including effects on vegetation
structure, trampling of nests and young (particularly waders) and dunging, which provides invertebrate food
(English Nature, 2001). Upland habitats provide significant breeding or foraging habitat for a unique mix
of ca. 40 bird species, of which 40% are currently declining. Of these, seven occur in internationally
important numbers, and eight are listed in Annex 1 of the EC Birds Directive 70/409/EEC (Thompson and
Miles, 1995). Existing knowledge concerning the ecology and habitat requirements of many of these is
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limited to a small number of broad-scale correlative studies (eg Brown and Stillman, 1993), and a few PhD
studies covering single site, single species autoecological studies (eg Whittingham, 1996; Pearce-Higgins,
1999). Changes in the scale and intensity of management practices in the uplands are implicated in the
deterioration of habitat quality for breeding populations of wading birds and passerines of international
conservation significance (EC Birds Directive) and for game birds of economic importance (Fuller and
Gough, 1999).
Investigations suggest that declines in bird populations are not simply the result of a direct interaction
between birds and cattle. The RSPB has produced evidence of the impacts of grazing on upland bird species
through changes in vegetation composition and structure from studies in the Southern Uplands of Scotland
and the Pennines of northern England. The research involved a correlation of the abundance of a suite of
breeding birds with detailed assessments of moorland vegetation and grazing intensity (Pearce-Higgins and
Grant, 2002). This study did not assess the mechanism of effects, and the role of arthropod food supply
remains a possible reason for reduced breeding success. The interaction between grazing animals and
nesting habitat or arthropod food for meadow pipits has been investigated in a three year project
coordinated by the Macaulay Institute. Unpublished data show that a reduction in grazing intensity to one
third of a commercial sheep grazing intensity doubled the arthropod biomass available to foraging birds.
In lowland farmland, the abundance of invertebrates is a critical factor accounting for the declines of
farmland bird populations (Fuller
et al
., 1995; Wilson
et al
., 1999; Chamberlain
et al
., 2000). However,
the relationships between farmland birds, their prey items and farm management practices are complex.
Insectivorous birds require arthropod food resources of adequate abundance in close proximity to their
nesting or roosting sites and the soil and vegetation structure needs to be such to allow access to these food
items (Berg, 1993; Beintema
et al
., 1991; Green
et al
., 1990).
Leatherjackets, larvae of craneflies (Diptera: Tipulidae), represent the largest invertebrate biomass in the
uplands and significantly contribute to the diet of the rare upland
Dotterel
,
Eudromias morinellus
(Charadridae) (Galbraith
et al
., 1993) and the economically important red grouse,
Lagopus lagopus
(Park
et al
., 2001). McCracken
et al
. (1995) indicated that the abundance of leatherjacket populations
eaten by birds is influenced by previous farm management practices in addition to the location and
characteristics of a site. In addition, both current and past farm management are important in determining
the availability of soil-dwelling arthropods to birds at any one time of year (Berg, 1993; Beintema
et al
.,
1991; Green
et al
., 1990). Furthermore, heterogeneity in habitat structure must be considered at a spatial
scale appropriate for the size and mobility of the birds (Morris, 1987; Wiens, 1989; Ziv, 2000) and their
life-history characteristics (Naugle
et al
., 1999). A lighter summer grazing regime on flatter, unenclosed
ground can provide a short sward of benefit for breeding waders such as golden plover, although different
waders have different requirements (Ausden and Treweek, 1995). Bignal
et al
. (1996) found that chough
(
Pyrrhocorax pyrrhocorax
) foraged for leatherjackets during the breeding season on grasslands of short
sward generated by intensive grazing by sheep, cattle and/or overwintering barnacle geese. This allowed
access to the prey but larger densities of leatherjackets were associated with grasslands where there had
been a taller sward in autumn related to a low stocking density of cattle. Such taller vegetation was preferred
by adult craneflies for egg laying. It is essential to increase our understanding of the interactions between
structure of vegetation and arthropod abundance before appropriate grazing management strategies can be
developed for conservation (eg McCracken
et al
., 1995; McCracken and Bignal, 1998; Perkins
et al
., 2000).
Caterpillars of moths (Lepidoptera), sawflies (Hymenoptera: Symphyta) and spiders contribute to the diet of
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black and red grouse (Baines, 1991; Baines, 1996). These caterpillars, in addition to the soil-dwelling
leatherjacket larvae (Diptera: Tipulidae) described above, are also essential in the diet of upland ground-
nesting birds, including waders of international conservation importance (Brown and Bainbridge, 1995).
Black grouse broods use upland grass or heather habitats with taller vegetation that have more arthropods,
particularly caterpillars but also including flies, plant bugs and parasitic wasps (Baines, 1996). However,
in this case the timing of the hatch of black grouse coincided with the peak availability of moth caterpillars
preferred by chicks. Adult black grouse also feed on cotton-grass
Eriophorum
flowers which is very nutritious
but is also consumed by livestock at moderate to high stocking densities. The availability of arthropods as
food to birds will be a product of the species composition, abundance and biomass of arthropods, their
guild, location in the soil or vegetation and their seasonality.
Table 4.2 Summary of key studies of impacts of grazing by cattle on birds
Study Facilitation Detrimental Reference
Grazing and moorland Cattle of mixed grazing Pearce-Higgins and
vegetation response systems removed favourable Grant, 2002
compared with upland botanical and structural
wading birds composition
Grazing and Upland Bird Higher density of meadow Dennis
et al
., 2005
experiment – upland acid pipits with larger eggs on
grassland vegetation grazed by cattle
mixed with sheep at one
third commercial stocking
rate
Cattle grazing of chough Provision of insect prey of Grassland damaged by Bignal
et al
., 1996
grassland in Western Isles chough in dung enhanced the continuation of out of
by cattle grazing season grazing
Cattle grazing for chough Cattle can maintain feeding Grazing vegetation too McCracken
et al
., 1995;
lawns for chough where short in autumn can inhibit McCracken & Bignal, 1998
they can access cranefly egg laying by adult
larvae in soil craneflies
Trampling and ground Eggs and nests can be Beintema and Müsken,
nesting birds damaged by higher stocking 1987
densities of cattle
Cattle can influence birds by trampling nests. Beintema and Müsken (1987) found in the Netherlands that
the probability of a nest surviving trampling was a simple function of stocking density and the number of
days of grazing, a similar finding to that of Green (1986) in the Ouse Washes. Of four types of grazing
(dairy cattle grazing during the day only, dairy cattle grazing day and night, young cattle grazing day and
night and sheep grazing day and night), young cattle were the worst tramplers. However the authors point
out that it was not clear to what extent re-nesting compensated for damage by trampling and the extent or
re-nesting will depend on the stage of the breeding season. O‘Brien (2001) found that on improved
grassland, horses caused more trampling damage to lapwing nests at a given stocking density, with sheep
causing least damage and cattle being intermediate. On unimproved pasture the damage was considerably
lower because of the lower stocking density although when stocking density was taken into account the
probability of a nest being trampled was similar.
There are many woodland birds that are conservation priorities but many of these will only be affected by
the long term effects of grazing on woodland plant species and structural composition.
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Mammals
In general, cattle grazing will affect other mammals indirectly through changes to the quality and quantity of
habitat. Red deer may benefit directly from the reduction in competition for forage with domestic herbivores
should there be a reduction in stocking densities. Changes in grazing, that may include the use of cattle to
achieve better habitat condition, should improve habitat quality for mountain hares and short-tailed voles.
One key species that is of considerable interest to land managers in upland areas is the field vole
Microtus
agrestis
. An increased abundance of voles was observed when livestock grazing was removed from
grasslands in Montana (Smit
et al
., 2001). This response could have both positive and negative implications
for biodiversity in the Scottish context as:
a) field voles are a major source of food for other species;
b) they are a major cause of damage to newly planted or established trees; and
c) they are potential vectors for diseases (Lyme‘s Disease, Louping ill, Anoplasma) that infect wildlife and
man, although there has been little research on the importance of this in the Scottish environment.
Cattle contribute as one species of a broader range of wild and domestic herbivores that affect the structure
and composition of upland woodlands. The effects are long term in contributing to the structural and floristic
species composition of woodlands and the precise impacts of cattle on the list of mammal species
associated with woods are tenuous. Native deer (roe
Capreolus capreolus
and red
Cervus elaphus
)
could be displaced from woods where there is intensive grazing by domestic livestock, including cattle
(Kirby
et al
., 1994, Hester
et al
., 1998, Mitchell and Kirby, 1990). Upland woods are important habitat
for the red squirrel
Sciurcus vulgaris
. Very large pinewoods (in excess of 2000ha) and composed mainly of
coniferous species provide the best refuges for red squirrels. A diverse age structure is ideal with 50–60%
of the trees being of cone bearing age. Young trees of 15–30 years provide good cover, and continuous
belts of trees linking seed-bearing areas are desirable. All these aspects could be managed using grazers,
possibly cattle, although most likely it is a case of excluding wild herbivores (English Nature, 2001). Upland
and upland fringe broadleaf woods with a good range of understorey shrubs can hold populations of
dormice
Muscardinus avellanarius
. Young plantations are valuable habitats for small mammals, when there
is a thick covering of ground vegetation. Later, similar conditions may be provided along wide grassy rides
(English Nature, 2001). Otters
Lutra lutra
may use riverside woodland strips and lines of trees as cover for
holts and hunting territory (http://www
.wwf.org.uk/core/wildlife/fs 0000000027.asp). Large upland conifer
plantations are important for pine marten
Martes martes
but cattle have little or no role in conserving this species.
Invertebrates
Insects and arachnids (arthropods) typically contribute more than half the species to the biodiversity in any
particular habitat (Anon, 1995). The overall diversity of insects and arachnids in the uplands is a product
of the adaptation of individual species to particular upland biotopes (habitats) and their specific guild.
In general, arthropod assemblages of heather and grassland biotopes in the uplands are distinct compared
with those of other habitats such as riversides, woodlands, marsh and grassland, eg ground beetle
(Luff
et al
., 1989), butterfly, moth and spider species (Ratcliffe, 1977). The species composition of these
arthropod assemblages is also very different within upland plant communities (Coulson and Butterfield,
1985), namely lowland mires, northern heaths, blanket bogs, steep-gradient peaty soils and upland limestone
grasslands. The greatest difference in insect assemblages is between heather and grassland, mainly because
of the association of phytophages with specific plants (Coulson and Butterfield, 1985); those of blanket bog
and peatland support the most distinct species.
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_
Cattle are generally better than sheep at maintaining a structurally patchy sward of benefit to arthropods.
This is partly due to the dunging behaviour of cattle. Cattle dung randomly across a sward and then avoid
dunged areas whilst grazing, and this develops into a series of tall sward islands that are favourable for
arthropods (Dennis
et al
., 1998; Dennis, 2003). Dung beetles are rare or absent from ungrazed grassland,
since the dung of small mammals is unsuitable for most dung feeders (Morris, 1990). A complete absence
of animal dung will lead to the loss of specialised arthropod species of the detritivore guild, such as
the nationally scarce dung beetle
Aphodius fasciatus
, which is associated with sheep and cattle dung in
moorland and montane areas (English Nature, 2001). Many other dung feeders are opportunists that
colonize rapidly over short distances, but if grazing is reintroduced after being absent from a large area the
rate of breakdown of dung and hence nutrient cycling will be suppressed over the period of recolonisation.
Many insect guilds are herbivorous (phytophagous) and depend on the presence of particular vegetation
types or plant species. Due to their small size, compared with the size of individual plants, and diverse
modes of feeding, they often select specific parts of a plant, such that they are sensitive to plant architecture
in addition to the presence of a suitable host species (Strong
et al
., 1984). The abundance of their
populations tends to increase with the standing biomass of their food plants. Predators are more dependent
on the physical features of their habitats. For example, web-spinning spiders depend on taller, more rigid
plants for web anchorage that may be present at low densities (Gibson
et al
., 1992b).
Small, insect herbivores, namely leafhoppers (Homoptera: Auchenorrhyncha) and other plant bugs
(Heteroptera) select for particular species or groups of plants (Whittaker and Tribe, 1998; Waloff, 1980).
Particular species will therefore associate with upland communities where these host plants are abundant
(Dennis, 2003) and direct competition between large herbivores and these insects will occur when grazing
selects those host plants and reduces their abundance within a particular upland community (Gibson
et al
.,
1992). Grazing herbivores have an indirect effect on many arthropods by modifying the structural
characteristics of upland habitats (Dennis
et al
., 1998). The structural appearance of vegetation can
be dramatically altered by the grazing regime, more so than plant species composition (Dennis, 2003;
Hulme
et al
., 1999; Grant
et al
., 1996a and b). The development of distinct tussocks or hummocks has
consequences for the distribution of small arthropods, both leafhoppers and spiders (Dennis
et al
., 1998).
These structural components of grasslands contributed to arthropod species diversity. More individuals and
species of leafhoppers were sampled in the taller, more complex components of grasslands, either tussock
or hummocks (Dennis, 2003). Further, the impact of increased grazing intensity on these insects was,
somewhat, buffered by these structures. The structural complexity of tussock-forming grasses encourages more
planthoppers and web-building spiders in upland grasslands (Cherrett, 1964; Dennis
et al
., 1998; 2001).
For wolf spiders (Araneae: Lycosidae), species which pursue prey and do not build webs, the reverse is true
and ca. 92% of individuals of this family mainly use the shorter grass between tussocks (Bayram and Luff,
1993). The relationships between grazers, vegetation and arthropods for upland, indigenous grasslands
were consistent with the situation in lowland grasslands. The diversity of many arthropod taxa of lowland
grasslands was favoured primarily by an increase in average vegetation height (Morris, 1990; Gibson
et al
., 1992a; 1992b; Kruess and Tscharntke, 2002).
If we consider predators requiring architectural diversity for the anchorage of webs, eg, the money spider,
Silometopus elegans
, its general abundance increases where there is a lower grazing intensity but declines
where grazing is absent for over two years (Dennis, 2003). By contrast, the common money spider,
Lepthyphantes mengii
, demonstrates a similar trend except that the highest catches were in the ungrazed
Nardus stricta
(Dennis, 2003). The difference is caused by the different locations of web building by these
spiders.
Lepthyphantes mengii
constructs webs high in the leaves of tussocks or hummocks and this microhabitat
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is increased where grazing ceases for longer periods (Dennis, 2003). Taller swards were the most influential
factor, typically being patchier, ie, having greater variability in sward height (Dennis
et al
., 1998).
Dennis (2003) found an interaction between grazing intensity and environmental conditions for leafhopper
and plant bug species indicated by the consistent declining numbers with increased stocking density.
There were fewer potential species on the less productive vegetation at high altitude, on wet, cold slopes,
eg
Festuca–Agrostis
. In addition, there was greater sensitivity of the plant bug species to grazing intensity
on the sites of lower productivity. Ground and rove beetles (Coleoptera: Carabidae, Staphylinidae),
predatory species that roam around on the ground over tens of metres, were sampled at 120 points where
pitfall traps were placed within the grazing experiment on
Nardus stricta
(U5a community). A geostatistical
procedure was used to determine the size and location of clusters of high and low numbers of beetle species
representative of the main trends of all the species (Dennis
et al
., 2002). Four distinct patterns were identified
that accounted for the main trends expressed by all species and the ecological interpretation identified
the relative influences of landform and grazing management (Dennis, 2003). A large south-facing cluster
that extended over several contrasting grazing treatments characterized
Calathus melanocephalus
(Col.: Carabidae;), and indeed this species is typical of productive lowland pastures. There was also a large
cluster across contrasting treatments for
Philonthus decorus
(Col.: Stapylinidae) and this showed the selection
of more northern conditions typified by soil of greater wetness and organic matter content. The remaining
two species both suggested responses to the patterns of grazing.
Olophrum piceum
(Col.: Staphylinidae)
had clusters only within the ungrazed plots and this probably relates to the increased litter and associated
fungi that would develop in the absence of grazing. The clusters of high numbers of the large species,
Carabus problematicus
(Col.: Carabidae) associated with plots grazed by sheep rather than sheep plus
cattle suggests that there are effects of cattle, possibly through soil compaction or direct treading disturbance,
that are detrimental to this species.
Carabus
spp. depend on soil crevices as daytime refugia to avoid
desiccation and predation, and the availability of these features may be reduced under cattle grazing.
Herbivores affect soil by compacting it where they tread and altering its nutrient status where they produce
dung and urine. This directly affects soil insects and arachnids and indirectly affects foliar insects and arachnids
by changing plant species composition through changes in soil status, as opposed to forage selection during
grazing. Trampling is seen as generally harmful to the arthropod fauna (Usher and Gardner, 1988), although
dung deposition provides a niche for additional species (Coulson, 1988). Sanderson
et al
., (1995) provide
further evidence of the importance that abiotic factors have in affecting the spatial patterns of arthropod
populations in upland landscapes at larger spatial scales. Soil moisture or site wetness is recognized as a
major determining factor in the distribution of many ground beetle species (Rushton
et al
., 1991).
The diversity of ground beetles, plant hoppers (Homoptera: Auchenorhyncha) and spiders (Araneae) in
grassland, heathland and montane ecosystems is related to botanical diversity and the structural variability
of vegetation (Coulson and Whittaker, 1978; Cherrill and Rushton, 1993, Downie
et al
., 1995; Sanderson
et al
., 1995; Dennis
et al
., 1998). For grasslands in general, there is a positive correlation between the
number of botanical species and the species richness of bees (Hymenoptera: Apidoidea), butterflies
(Lepidoptera), phytophagous beetles (Coleoptera: Chrysomelidae) and true bugs (Hemiptera) (Tscharntke
and Greiler, 1995). Differences between insect and arachnid species in the effects of grazing are
highlighted by work undertaken in Wytham Woods, Oxfordshire (Brown
et al
., 1990, Gibson
et al
.,
1992a and b). For spider assemblages, changes in plant architecture were found to be most important,
while other species (eg leaf miners) were affected more by variations in floristic species composition. As a
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consequence, leaf miners had a rapid turnover whereas spider species accumulated over time. Age of
grassland was also important; there are common species of spiders, leaf miners and leaf hoppers
(Cicadellidae) that are restricted to grasslands >60 years old (Gibson, 1986).
Although general arthropod diversity is diminished by intensive management, many species respond within
a few years to favourable changes in vegetation structure and botanical species composition that result
from modified management (Duffey
et al
., 1974; Brown
et al
., 1990; Gibson
et al
., 1992a; Curry, 1994;
Dennis
et al
., 1998). Similarly, Coleoptera (beetles) of lowland grasslands are affected by the intensity
of pasture management and species of ground beetles (Carabidae) have been identified that are resilient to
or excluded by such management (Eyre
et al
., 1989; Luff and Rushton, 1989)
Table 4.3 Summary of key studies of impacts of grazing by cattle on invertebrates
Study Facilitation Detrimental Reference
Cattle grazing on upland Maintain structurally patchy Combined with sheep Dennis
et al
., 1998
acid grasslands sward better than sheep – can remove structural
benefit to arthropods in heterogeneity
general
Grassland spiders Height variability provides More widespread trampling Dennis
et al
., 2001;
greater opportunity for web interferes with web building Bayram and Luff, 1993;
construction for spiders and spiders Cherrett, 1964
hunting lawns for wolf spiders
Ground beetles Can increase structural Combined with sheep, Blake
et al
., 1994;
diversity and increase excludes larger species, Dennis
et al
., 1997;
species richness possibly because soil Eyre
et al
., 1989
crevices are trampled out
Dung beetles Most larger species depend Morris, 1990;
on cattle rather than sheep English Nature, 2001
dung
Rove beetles Dung associated predators Different species composition Dennis
et al
., 1997
benefit from cattle dung in lawn and tussock areas,
hence a mosaic is required,
avoiding continuous cattle
grazing. Many species of
composting litter absent
under cattle grazing due to
trampling and consumption
of higher proportion of
dead vegetation
Plant bugs, including Can diversify vegetation More grazing with cattle Dennis
et al
., 1998;
leafhoppers and number of host plants as part of mixture reduces Dennis, 2003;
at low stocking densities species number and Gibson
et al
., 1992b
abundance through direct
competition
General arthropod diversity Rotational grazing with low Morris, 1971; 1990; 1991;
to moderate stocking Thomas ,1990;
densities of cattle mixed Dennis
et al
., 1997; 1998;
with other livestock provides Dennis, 2003
mosaic that may support the
potential arthropod diversity
that cannot be supported
by any particular grazing
regime
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Fish
There is little literature on the direct effects of cattle on fish. The effects of livestock management in general
on water quality in water courses, and management actions to reduce negative impacts are dealt with
in
The 4 Point Plan
. This is a joint publication between a number of agencies: the Scottish Executive,
Scottish Environment Protection Agency, Scottish Agricultural College, The National Farmers’ Union
of Scotland, Scottish Natural Heritage, The World Wildlife Fund, the Farming and Wildlife Action
Group and the BOC Foundation. The plan covers all aspects of pollution from farms (see:
http://www.sepa.org.uk/pdf/publications/4pointplan.pdf.
One study on Dartmoor described how allowing cattle access to a watercourse resulted in compaction
of the gravel in the river bed which meant that salmon could not dig out the hollows they need to lay
their eggs. The solution lies in fence off vulnerable river banks to deny access for cattle (see:
http://www
.actionforwildlife.org.uk/ProjectDisplay.asp?ID=11).
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5 EFFECTS OF CATTLE FARMING SYSTEMS ON THE NATURAL HERITAGE
Previous chapters have concentrated on the effects of cattle on particular habitats or species, but it must be
recognised that cattle are part of the wider farming system. Thus if cattle are deemed to be able to deliver
environmental benefits there is a need to consider:
a) the barriers to the introduction (or reintroduction of cattle into farming systems); and
b) the environmental impacts of farming systems (as opposed to the direct effects of cattle on habitats
or species).
5.1 Introducing cattle into farming systems
Cattle were at one time a significant feature on most Scottish farms, but recent decades have seen a major
shift within the agricultural industry towards greater specialisation, with farmers concentrating on fewer
enterprises with more intensive management of those enterprises. Where farms no longer have cattle there
are a number of obstacles to their reintroduction, particularly on hill and upland farms. The barriers to the
introduction (or reintroduction) of cattle onto farms fall into three categories: capital requirements,
infrastructure requirements and labour requirements
Capital requirements
The capital requirements for the purchase of cattle are high, especially if a breeding herd is to be
established: the capital value of a cow with a calf at foot can be in excess of £1000 and up to £1200.
Farmers wishing to start a breeding herd therefore require access to considerable quantities of capital, either
from their own resources or by borrowing. Growing cattle, purchased for grazing may require a lower
capital investment, over a shorter period (perhaps for only six months between purchase and sale), but
nonetheless the capital investment is still considerable. Alternative mechanisms by which cattle could be
introduced include summer grazing by cattle owned by another farmer. This may be particularly suitable for
grazing replacement heifers. Thus greater co-operation between upland and lowland farmers, whereby the
stock can be wintered on lowland farms, where winter feeding can be more easily provided and then
returned to the hills for the summer grazing period may be one mechanism by which greater numbers of
cattle could be kept on hill farms.
Infrastructure needed for cattle
Any cattle enterprise requires access to infrastructure of different types. This includes handling facilities,
machinery for preparation and feeding of fodder and possibly housing.
Where a very low intensity system is proposed, with cattle remaining outdoors all year round, housing may
not be required. However, on many farms it will be desirable for the cattle to be housed in winter, either to
ensure an appropriate standard of animal welfare, and/or to prevent the cattle from causing environmental
damage due to grazing and trampling of habitats. Housing for cattle is expensive, as are proper waste
disposal facilities, which are mandatory. Many farms still have old cattle buildings but these are often
unsuitable for present requirements. Often these traditional buildings require the cattle to be individually fed
and mucked out by hand which is very labour intensive. Also, for Organic Standards, the use of traditional
tie stalls is forbidden and slatted floors are forbidden in lying and feeding areas in cattle housing on the
grounds of animal welfare (Lampkin, 1998).
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In addition to appropriate housing, there must be provision for waste disposal, either straw-based farmyard
manure or slurry, and provision may need to be made for storage of winter fodder, either hay or silage.
Appropriate handling facilities are essential to ensure that stock receive proper veterinary and welfare care,
in addition to ensuring the safety of those who work with cattle. Such facilities, including handling pens,
raceways and a crush, are more expensive than those required by sheep.
Labour required for cattle
Labour requirements for a cattle enterprise can be high, particularly during winter when feeding is necessary.
On most farms financial pressures have led to a considerable reduction in labour availability compared with
10 or 20 years ago and an increase in mechanisation. This trend is likely to continue with CAP reform and
the introduction of the Single Farm Payment. The management and handing of cattle often requires more than
one person (unlike sheep) and on many farms, particularly in upland areas, this level of labour may not be
available. Cattle enterprises also require much larger quantities of winter fodder to be made compared to
sheep. A spring-calving beef cow for example will require about 6 tonnes of silage over winter. However,
silage and haymaking operations can be undertaken by contractors, particularly silage making which is
highly mechanised.
5.2 Provision of winter fodder
The ability to provide winter feed for cattle can often be one of the key determinants of the numbers of cattle
kept on a farm, especially on hill farms because of the limited land suitable for the conservation of fodder.
Silage-based systems require the use of expensive machinery, and it may need to be transported to the
animals. Making hay can be labour intensive and, particularly in the west of Scotland, risky due to bad
weather.
In the past the ‘Sheiling‘ system was practised in many hill areas where cattle and sheep spent the summer
away from the farm on more distant pastures. This meant that the land near the farm could be used for limited
arable cropping and for haymaking and the livestock would then be returned to the in-bye land for over-
wintering. Such a system allowed the grazing of the hill pastures to control species such as purple moor
grass. It also allowed a measure of self sufficiency in terms of winter feeding with less reliance on bought-
in hay and concentrates. However, these systems have been abandoned in favour of more intensive methods
of production. Instead of the species-rich hay meadows, silage is made from well fertilised swards composed
of fast growing and late heading ryegrass monocultures.
Where there is suitable available land for the production of winter fodder hay or silage can be made.
On farms with smaller numbers of cattle, and where there is a limited supply of labour, haymaking may be
the preferred option but on larger farms silage will be more suitable, particularly as it more easily lends itself
to the employment of contractors and is much less weather dependant. Silage can be made in a pit or
clamp, or conserved in large bales, wrapped with plastic film. The former option is only really viable if the
farm already has a suitable silage pit, with proper provision for effluent storage. On many upland and hill
farms and on many small farms and crofts, big bale silage is the preferred option, being easier to make and
easier to feed in the winter, to either housed or outwintered stock. Big bale silage, while convenient, is not
necessarily a low cost option for two reasons. Firstly, the actual conservation process is considerably slower
than for pit silage, with much slower workrates. Secondly, the plastic wrap is more expensive, and is likely
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to become more so in the future, being closely related to the price of oil. Plastic wrap for big bales has
a considerable pollution potential, although schemes for recycling are now in place in some areas. There is
also a considerable potential for effluent seepage from stacks of silage bales and for this reason they should
not be stored less than 10m from watercourses.
Concentrates and bedding
At certain times of the year cattle may require greater levels of nutrition than can be provided by bulky
roughage feeds like hay and silage. Depending on the feed quality of the roughage component of the diet,
concentrate feeding may be required at key times of the animals‘ production cycle if reasonable levels of
economic production are to be sustained and the welfare of the animals is not to be compromised eg in late
winter and early spring, in the run up to calving when the nutritional demands of the growing foetus may be
greater than can be provided for by a cow being fed only a roughage diet. This is particularly the case if
the diet is mainly based on hay which tends to be of poorer nutritional quality than silage. The cow will
require a supplementary feed, which is usually based on cereals like oats or barley. For many farms the
easiest option is to purchase the concentrate feed, although some farms may grow at least some of
their own requirements. The introduction of arable cropping onto a farm can have a positive effect on
the natural heritage by creating new ecological niches and sources of food for wildlife. On many farms,
the straw component of the cereal crop is almost as important as the grain, being essential for bedding.
Home produced straw can substantially reduce the requirement for bought in straw.
5.3 Positive effects on the natural heritage of farming systems involving cattle
Dung and invertebrates
Cattle dung attracts large numbers of invertebrates, which are an important part of the food chain,
particularly for birds (see Chapter 4). However it should be noted that some anthelmintic products, especially
the invermectins, can pass through the animal and reduce the numbers of insects in the dung (Strong and
Wall, 1994).
Fodder production
One of the important influences of cattle on a farm is that the production of hay and/or silage results in much
taller grass swards being present in early summer than is the case with grazed herbage. Historically, most
winter fodder was conserved as hay, cut from meadows usually containing a diverse range of grass and
broadleaved species (Hughes and Huntly, 1988; Myklestad and Saetersdal, 2004; Kirkham and Tallowin,
1995). More recently, fodder conservation, even on upland farms, has been made from sown grassland
containing only a very few species such us perennial ryegrass, perhaps with some white clover. These fields
are usually treated with artificial fertilisers and are highly productive but compared to traditional hay
meadows are species-poor. The method of conservation has also changed, with haymaking being replaced
by silage making on most farms.
From the farmer‘s point of view, silage has a number of advantages over hay. Silage making needs a much
shorter period of good weather to secure the crop compared with hay. Particularly in the wetter areas of the
country, it can be very difficult to get a three or four day period of good weather, which is the minimum for
making good hay.
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Silage making also tends to take place earlier in the season than haymaking. Silage making allows farmers
to conserve the grass at a younger and more nutritious stage of its growth cycle. Making hay from young,
leafy grass is difficult since the moisture content of the leafier material is higher and the cut grass takes longer
to dry. Much of the leaf can be lost during turning and spreading, so for making hay, cutting is usually
delayed till the crop is more mature. The result is fodder which is easier to make but is of poorer nutritional
quality than silage.
The switch to silage making however has fewer positive effects on the natural heritage than haymaking,
mainly due to the material being harvested about 4 weeks earlier than hay. This four-week difference
has the potential to impact directly on ground nesting birds such as the corncrake (Stowe
et al
., 1993;
Green and Stowe, 1993). Seed eating birds can also be affected by the switch from hay to silage.
The earlier cutting of silage means that the crop is harvested before the seeds are shed. Buckingham
et al
.
(2002) found that seed eating species tended to avoid silage fields in the summer time. They also found that
seedeaters tend to be attracted to hay field aftermaths.
Hay meadows are important habitats due to the rich diversity of plants found within them. However Kirby
(1992) found that they are not particularly good habitats for invertebrates. The swards tend to be too tall
for invertebrate species which live near to ground level and prefer short swards. As the crop reaches maturity
it tends to be harvested just as it becomes a useful habitat for those species which prefer taller swards.
He concluded, however, that hay meadows are still a very desirable feature in the landscape for the other
biodiversity features which characterise them.
Cereal production and other arable cropping
Cultivation of crops can create ecological diversity within a farm (Allen, 1999) by creating a greater
diversity of land cover. Spreading of dung, either onto grassland or prior to ploughing can increase the
number of invertebrates available for insect eating birds. After sowing, the bare ground and the growing
crop provides nesting sites for species like lapwings, skylarks and oystercatchers. Wild flowers can develop
within the cereal crop and if allowed to set seed will, together with grain shed from the harvesting operation,
provide food for seed-eating birds. The stubble left over the winter also provides shelter, not just for seed
eaters, but also for insect eaters. The ploughing of older grassland and the cultivation of a cereal crop is not
necessarily a negative process. Good and Giller (1991) found in South West Ireland that Staphylinid
assemblages recovered very quickly from ploughing once a new crop or grass canopy was established.
5.4 Negative effects on the natural heritage of farming systems involving cattle
Trampling and poaching of the ground
Cattle can have detrimental effects on the soil and vegetation under certain conditions. This is particularly
the case if they are kept outdoors in winter or when the ground is saturated and the stocking rate is too high.
In extreme case there can also be a problem with run off into watercourses. Generally these adverse effects
are restricted to feeding areas, and if these are sited correctly and the stocking rate is appropriate these
problems can be minimised. There is often a temptation to keep cattle outdoors as long as possible in the
autumn/early winter to reduce the winter feed requirement as well as to restrict the amount of dung and
slurry which will build up and will require subsequent handling and disposal. However, extending the
grazing period can lead to nutrients leaching into watercourses. Modelling work by McGechan (2002)
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looked at phosphorous leaching during extended grazing and concluded that extending the autumn grazing
period significantly increased the risk of phosphorous leaching into watercourses. This supported previous
experimental work and the resultant advice is that cattle should be housed before soil macropores fill up with
water. When this occurs will be dependent on a number of factors, including soil type and rainfall and may
vary from year to year.
Disposal of dung and slurry
Keeping cattle indoors leads to the production of either farmyard manure or slurry, depending on the type
of housing arrangements. This material has a high concentration of nutrients for grass and crop growth. It is
also a serious potential source of pollution, particularly to water courses and ground water. Attention must
be paid to careful storage and disposal, particularly with slurry to avoid contamination of watercourses.
Smith
et al
. (2002) recommend that account needs to be taken of the nutrient status of the manure, the soil
type and weather conditions at and around the time of spreading. Slurry applications to land should be
avoided during the months of September, October and November. There are further restrictions on
application of organic manures within Nitrogen Sensitive Areas.
Run off from yards
A significant source of pollution can be run-off from farm steadings, roads and tracks and uncovered manure
heaps (Hatch
et al
., 2004; Aitken
et al
., 2004). Care needs to be taken to collect and properly dispose
of dirty water from steadings and handling yards and dung heaps should be carefully sited to avoid proximity
to watercourses and drains. Vinten
et al
. (2004) tried to determine the effects of fencing watercourses to
exclude livestock. The results were made difficult to interpret because of uncontrolled runoff from steadings.
Damage to watercourses
Cattle may use streams and rivers as their source of drinking water, even if water troughs are readily
available. This can cause damage to banks and stream beds. In addition the streams will become polluted
by urine and faeces. Information on this aspect of pollution control is available in
The 4 Point Plan
(http://www.sepa.org.uk/pdf/publications/4pointplan.pdf). The adverse effects of cattle on a watercourse
are also described at http://www
.actionforwildlife.org.uk/ProjectDisplay.asp?ID=11. This describes the
problem of compaction of the gravel in a river bed on Dartmoor which meant that salmon could not dig out
the hollows they need to lay their eggs. The solution for many of these problems is to fence off vulnerable
river banks to deny access for cattle.
Silage effluent
Silage making involves storing grass at much higher moisture contents than hay, the material being preserved
by fermentation rather than drying. As mentioned above, the feeding value of silage is usually much higher
than hay and the operation is at considerably less at risk from bad weather. If silage is made from grass
with a high moisture content, effluent will exude from the silage. Generally, if silage has a dry matter content
of less than 26–28% effluent will be an issue (Frame, 1992). Effluent from silage is a very serious pollutant,
often quoted to have as much as 200 times the polluting power of domestic sewage. Although an obvious
solution is to ensure that the dry matter content of the grass is high enough before the crop is stored, by
wilting the grass before ensiling, this may not always be possible, especially during periods of wet weather.
Thus, silage stores have to have provision for collection of any effluent which may result. Similarly, stacks of
big bales of wrapped silage have to be stored well away from watercourses and species-rich grassland.
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Silage wrap
It has become common practice on many farms to make silage in big bales wrapped with plastic film. Once
the silage has been fed, the used plastic wrap is a potential pollutant. Old plastic wrap can be a hazard to
wildlife and is aesthetically unattractive as it can often end up strewn over fences and hedges and flapping
around trees. A survey of waste plastic on farmland in the Swale Valley in Northern England found a considerable
amount of waste plastic strewn around the countryside (http://www
.riverswale.org.uk/project07.html).
Waste plastic should be collected and stored for proper disposal. The best method is to send it for recycling
and a number of schemes are run throughout the country.
General pollution issues
Information on how farmers can best tackle issues of waste management and pollution control can be found
in the ‘The 4 Point Plan‘ and Prevention of Environmental Pollution from Agricultural Activity (PEPFAA )code
of good practice. Widdeson
et al
. (2004) found that there are large gaps in the knowledge of farmers with
respect to the relevant legislation about pollution. This suggests that while there may be potential benefits for
the natural heritage from the keeping of cattle on farms, raising the awareness and increasing environmental
education amongst farmers may be necessary to ensure that any potential benefits are not outweighed by
negative environmental impacts. One recent initiative, described by Langan (2004), approaches these issues
in a coordinated way at the level of the catchment in the Tarland Catchment Initiative in Aberdeenshire.
5.5 Examples of systems where cattle are used to benefit the natural heritage
Cattle are already being widely used in order to manage the natural heritage, but often only as grazers to achieve
specific goals. Often they are only used for short periods of time to remove invasive plant species at certain
times of the year. However there are examples of how cattle can be used as part of a whole farm system.
A good example is the management of the Pennine Dales ESA. Farmers are compensated financially for
continuing to use traditional management methods. This includes continuing to manage hay meadows and
maintain small fields (Younger and Smith, 1994).
On Exmoor and Dartmoor, cattle and ponies are used to manage moorland habitats (Smallshire
et al
.,
1996). The authors point out that these ecologically benign farming practices are only sustainable if the
financial viability of the farms is maintained.
Bignal
et al
. (1999) discuss the ecological significance of cattle rearing in very low intensity systems and
then describe in some detail examples of such systems on Islay and Mull. Highland cattle are used to graze
extensive rough grazings with low inputs. The herd on Islay is fed in winter with sheaves of oats
1
which are
grown on some of the farm‘s in-bye land. This in-bye land is also used to winter the young stock before they
are transferred to a hill park of upland and coastal grazings. The cows remain on the hill all year round.
On Mull, the herd is run in a similar fashion, but the young stock are sent for finishing to a farm in Perthshire.
This is a good example of how environmental benefits can be achieved by co-operation between farms,
even if they are a considerable distance apart.
1
The recently introduced Tier 2 of Land Management Contracts provides payment for the harvesting of cereal crops by
binder
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On the Uists there is a scheme to encourage cattle production on the Islands, in response to a steady decline
in cattle numbers, sometimes as high as 66% over a 10 year period. The report prepared by SAC (1997)
describes the scheme and the benefits to the natural heritage of continuing to have cattle as part of the
farming and crofting systems. The role of cattle in the natural heritage of the Scottish Islands is also mentioned
by Badger (1999) in a report for RSPB Scotland.
5.6 Conclusion
Cattle can play an important and positive part in improving, enhancing and maintaining the natural heritage,
but consideration has to be made of the way a cattle enterprise will fit into a whole farming system.
Their effects on the natural heritage at the system level are generally positive, provided they are managed
correctly and the objectives of cattle management are clear. The negative impacts usually concern issues of
overgrazing and pollution, both of which can be controlled by appropriate management.
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6 CONCLUSIONS
Cattle are less selective in their grazing behaviour than other domestic herbivores.
This results in different impacts on unimproved, semi-natural habitats compared to, for example, sheep.
Compared to other domestic grazers, cattle result in:
o a more structurally diverse sward;
o a reduction in the cover of tussock forming species;
o creation of more niches for plant regeneration.
There is a lack of empirical objective information on the impacts of cattle grazing for many unimproved
habitats.
For the habitats for which there is empirical information, in most cases, grazing by cattle is either beneficial
or at least neutral,
provided that the grazing is at an appropriate stocking density and seasonal pattern
.
Cattle should not graze bog vegetation (blanket bog and raised lowland bog).
There have been no scientific studies of foraging behaviour of different breeds of cattle.
There is very little information on the effects of cattle grazing on priority species.
As well as having a direct effect on habitats, cattle can affect the natural heritage by being part of the
faming system.
Potential negative effects of cattle farming systems include trampling and poaching, bank erosion, and
pollution of water courses from farm yard manure, slurry and silage effluent. These impacts can all be
minimised by adhering to good practice guidelines.
Positive impacts of cattle farming systems include dung, where it supports high populations of
invertebrates, fodder production which can result in hay meadows and small-scale cereal production.
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SUMMARIES OF PAPERS AND REPORTS COVERING THE EFFECTS OF CATTLE ON
THE NATURAL HERITAGE
Allen, S. (1999). Cattle and the environment: A report on the impact of cattle in the crafting counties.
Unpublished report to SNH.
This collates information from the literature, supplemented by information gathered from technical experts on
the impact of cattle on the environment in the crofting counties of Scotland. It covers the broad vegetation
types found in the area. It concludes that, with appropriate management, cattle can provide environmental
benefits to all habitats (apart from blanket bog) in the Crofting Counties, although it points out that for some
habitats types, especially small scale woodlands and common grazings, there is a lack of information.
Financial and social constraints are inhibiting the keeping of cattle in the Crofting Counties.
Andresen, H. et al. (1990). Long-term changes of salt marsh communities by cattle grazing.
Vegetation
,
89, 137–148.
This was a nine year experimental study of the effects of reducing cattle grazing on vegetation and
invertebrate assemblages. The background grazing was 2 cattle ha
–1
, and three, unreplicated exclosures
were set up with 1, 0.5 and 0 cattle ha
–1
. As expected the vegetation increased in height with reduced
grazing. However, sedimentation rates increased as well allowing invasion of upper marsh plant species.
Reduced grazing also resulted in increased population densities, higher species richness and diversity of
invertebrates. It also led to the invasion of upper marsh species and an indication that salt-tolerant species
might be lost. The food-web also switched to one dominated by detritus feeding species rather than those
feeding directly on plants. The conclusion, supported by the data, suggests that setting grazing levels at
c. 0.5 cattle ha
–1
should be recommended for nature conservation purposes.
Anonymous (1995). Biodiversity: the UK Steering Group report.
Meeting the Rio challenge and action plans
.
Volume 1. Introduction
. Her Majesty‘s Stationery Office, London.
General description of habitats and their status categorized into Habitat Action Plans. Little or solely anecdotal
information related to the role or effects of grazing but little reference specifically to cattle grazing.
Armstrong H. and Bullock, J. (2003). Stock grazing of woodland part 2.
Biotype no. 25
, pp. 1–3.
Non-peer reviewed summary of national survey of stock grazing in woodland.
Armstrong, H.M. et al. (2003). A survey of cattle-grazed woodlands in Britain. Report of the Forestry
Commission.
This is a non-peer reviewed report of a questionnaire survey of grazing management practice applied to
semi-natural woodlands. The survey revealed that most woodland in Scotland is grazed by cattle for
commercial livestock production in contrast to the results from England and Wales which indicated that
nature conservation was the primary objective of cattle grazing. The implications are that woodlands in
Scotland are grazed at high stocking densities and will be ecologically degraded.
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Ausden, M. et al. (2005). The effects of cattle grazing on tall-herb fen vegetation and molluscs.
Biological
Conservation
, 122, 317–326.
This was an experimental trial to see if the use of cattle grazing was capable of maintaining sites that had
previously been managed by cutting but had subsequently been abandoned. Highland cattle were
introduced to a small area of unmanaged tall-herb fen at Mid Yare RSPB Reserve, Norfolk with the aim of
restoring and maintaining derelict fen. Grazing was light (average of 0.4 livestock units ha
–1
) but there
were problems maintaining animal condition. There was a shift in dominance from
Phragmites australis
to
Glyceria maxima
, and an increase in species richness of the vegetation. Both changes replicated that
seen during cutting. However, grazing was detrimental to populations of a rare snail
Vertigo moulinsiana
.
They concluded, rightly, from this work that light grazing in the summer was an appropriate management
tool to increase species richness is previously derelict fen. Winter grazing was also advantageous, but was
problematical as even hardy cattle such as Highlands can lose condition. However, even light grazing
impacted on some invertebrate populations, though the same impact would be seen in a succession to
woodland. It was recommended that very wet areas be left ungrazed to solve this issue.
Bacon, J.C. (1998). Examples of current grazing management of lowland heathlands and implications for
future policy.
English Nature Reports Number 271
.
Unpublished report based on interview/survey of expert knowledge and management best practice on
lowland heathlands. General recognition of role of grazing livestock in the maintenance of the conservation
status of lowland heathlands, in particular the contribution of cattle and/or ponies in suppressing birch scrub
and the competitive dominance of
Molinia
.
Badger, R. (1999). Cattle and conservation in the Scottish Islands.
RSPB Scotland Report 1999.
This is a report of a series of seminars held by RSPB which looked into the role of cattle on the Scottish
Islands. The publication mentions many of the benefits associated with grazing, particularly by cattle, but
also puts the keeping of cattle in a farming systems context. For example, it includes aspects such as winter
fodder, arable cropping and labour implications. The report makes much of the policy implications for cattle
grazing and discusses agri-environment schemes.
Bakker, J.P. et al. (1997). Options for restoration and management of coastal salt marshes in Europe.
In: K.M. Urbanska, N.R. Webb and P. J. Edwards, eds.
Restoration Ecology and Sustainable Development
.
Cambridge University Press, Cambridge. pp. 286–322.
This is a review of the history, use and ecology of salt marshes with a focus on restoration and management.
It concludes that grazing is necessary to maintain species richness, as cessation of grazing leads to the
dominance of a small number of plant species, and that ‘moderate‘ grazing levels should be maintained or
introduced to manage salt marshes.
Beintema A.J. and Müsken G.J.D.M. (1987). Nesting success of birds breeding in Dutch agricultural
grasslands.
Journal of Applied Ecology,
24, 743–758.
This peer reviewed paper explores the impact of predation and trampling of nests in agricultural grasslands
in the Netherlands. Damage by trampling by domestic livestock was a simple function of stocking density
and days of exposure. Of four types of grazing, dairy cattle grazing during the day only, dairy cattle
grazing day and night, young cattle grazing day and night and sheep grazing day and night young cattle
were the worst tramplers.
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Bignal, E., McCracken, and Mackay A. (1999). The economics and ecology of extensively reared
Highland cattle in the Scottish LFA: An example of a self sustaining livestock system.
2nd International
Conference of the LSIRD Network Livestock Production in the LFAs,
3–5th December 1998, Bray, Ireland,
Macaulay Institute, Aberdeen.
This paper argues the case for cattle grazing on an extensive basis as being of significant benefit in terms
of economics and culture as well as ecology. The authors look at whole systems of production rather than
cattle simply being used as grazing tools. Two examples are given of extensive systems which are operated
successfully in the Hebridean Islands of Mull and Islay.
Blake, S. et al. (1994). Effects of habitat type and grassland management practices on the body size
distribution of carabid beetles.
Pedobiologia
38, 502–512.
Peer reviewed primary source literature. Structured ecological survey of contrasting habitats/management.
Descriptive study provides some evidence that increased livestock stocking densities and grazing by cattle
compared with sheep may select for smaller body sized ground beetles in grasslands.
Bokdam, J. and Gleichman, J.M. (2000). Effects of grazing by free-ranging cattle on vegetation dynamics
in a continental north-west European heathland.
Journal of Applied Ecology
37, 415–431.
This is a report of work in Holland where grazing is being used to manage biodiversity in several grass-rich
heathland habitats. Compared to ungrazed areas, species richness increased in grazed
Deschampsia
and
Molinia
areas. However at the stocking rates which were used, grazing did not stop the invasion of
Deschampsia
into
Calluna
habitat, although there was a significant recovery of
Calluna
in the grass heaths
on podzolic and peat soils.
Bonte, D., Maelfait, J.P. and Hoffmann, M. (2000). The impact of grazing on spider communities in a
mesophytic calcareous dune grassland.
Journal of Coastal Conservation
, 6,135–144.
This was a survey of spider assemblages on a calcareous dune system in Belgium. The intensity of cattle
grazing was a major determinant of the assemblage. Many of the rare species were associated with open,
heavily grazed areas. However, many species had juvenile stages that required tall vegetation with a litter
layer. The sensible conclusion was that management through extensive grazing that resulted in a patchy
mosaic of different grassland structures was the most appropriate method to manage for spider diversity.
Bouchard, V. et al. (2003). Sheep grazing as management tool in Western European saltmarshes.
Comptes Rendus Biologies
, 326 Supplement 1, S148–S157.
This study combined an analysis of a natural experiment on the effects of sheep grazing on salt-marsh
vegetation and an experimental study of the effects of grazing cessation. The evidence and hence their
conclusions were that moderate grazing enhanced plant species richness and diversity, and that abandonment
reduced the conservation value of salt marshes.
Brown, V.K., Gibson, C.W.D. and Sterling, P.H. (1990). The mechanisms controlling insect diversity in
calcareous grasslands. In: S.H. Hillier, D.W.H. Walton and D.A. Wells, eds.
Calcareous grasslands –
ecology and management
, Bluntisham Books, Bluntisham, pp. 79–87.
Non-peer reviewed secondary literature. Pseudo-replicated experiment (large plots without adequate replication
or random allocation of treatments). Investigation of floristic and structural changes in vegetation following
abandonment of cultivation and effects on invertebrates.
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Buckingham, D.L., Peach, W.J. and Fox, D. (2002). Factors influencing bird use in different pastoral
systems.
Conservation pays? Reconciling environmental benefits with profitable grassland systems.
Proceedings of the joint British Grassland Society/British Ecological Society Conference
, University of
Lancaster, 15–17 April, 2002. BGS Occasional Symposium No.36, British Grassland Society, Reading,
UK. pp. 55–58.
This paper presents the results of a study into bird distribution in relation to grassland management practices.
The study suggests that a switch from hay to silage could account for a decline in seed eating species, but
cattle grazing appears to benefit some species. High nutrient inputs seemed to favour some species and
there was no evidence that organically managed grassland cause any benefit to farmland birds. Grass field
margins, such as those generated by the Countryside Stewardship Scheme were favoured by seed eaters.
Bunce, R.G.H. and Barr, C.J. (1988). The extent of land under different management regimes in the
uplands and the potential for change. In: M.B. Usher and Thompson, D.B.A. eds.
Ecological Change in the
Uplands
.
Special Publication Number 7 of the British Ecological Society
. Blackwell Scientific Publications,
London.
Non-peer reviewed secondary literature. Structured ecological survey of contrasting habitats/management.
No specific information on the effects of cattle grazing but results presented on the extent of different upland
habitats and general anecdotal evidence of contemporary changes in management intensity.
Carvell, C. (2002). Habitat use and conservation of Bumblebees (
Bombus
spp.) under different grassland
management regimes.
Biological Conservation
103, 33–49.
A study looking at different management regimes and their effects on the populations of bumble bees on
military ranges in England. The results showed that grazing by cattle can have a positive effect on the habitat
which is favoured by bumble bees and consequently on their numbers. The effect of the cattle was to
maintain species richness by the removal of invasive species.
Cherrett, J.M. (1964). The distribution of spiders on the Moor House National Nature Reserve, Westmorland.
Journal of Animal Ecology
33, 27–48.
Peer reviewed primary source literature. Structured ecological survey of contrasting habitats/management.
Results of the effects of sheep grazing rather than cattle grazing on vegetation structure and spider
distribution and abundance. Demonstrated that tussock grass species can deter foraging sheep and protect
the spiders in some areas from grazing disturbance, even at commercial stocking densities.
Cherrill, A.J. and Rushton, S.P. (1993). The Auchenorhyncha of an unimproved moorland in northern
England.
Ecological Entomology
18, 95–103.
Peer reviewed primary source literature. Structured ecological survey of contrasting habitats/management.
Study restricted to effects of sheep grazing on true bugs of moorland.
Common, T.G. et al. (1997). The effects of
Molinia
utilisation on diet selection and herbage intake by
cattle grazing
Molinia
grassland.
Grass and Forage Science
, 52, 207–218.
An experiment looking at two different utilisation rates of
Molinia
and the effects on both the cattle
performance and the floristic diversity. It was found that at 33% utilisation of the
Molinia
, the proportion of
Molinia
in the swards was maintained as was adequate cattle performance. For a higher utilisation rate, there
was a decline in the proportion of
Molinia
in the sward, although cattle performance remained acceptable.
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Common, T.G., Wright, I.A. and Grant, S.A. (1998). The effect of grazing by cattle on animal performance
and floristic composition in
Nardus
-dominated swards.
Grass and Forage Science
, 53, 260–269.
Peer reviewed primary source literature – replicated experiment. Investigated the effects of two grazing
intensiies by beef cows and their calves on
Nardus
-dominated grassland on animal performance and
botanical composition. In early summer Blue Grey cows and their calves gained live weight, but from August
cows lost live weight and their calves grew less well. Grazing for about eight weeks in early summer was
recommended. The proportion of
Nardus
in the sward was reduced, especially at the higher grazing
intensity.
Coulson, J.C. (1988). The structure and importance of invertebrate communities on peatlands and
moorlands, and effects of environmental changes. In: M.B. Usher and D.B.A. Thompson, eds.
Ecological
change in the uplands
, Blackwell Scientific Publications, Oxford, pp. 365–380.
Peer reviewed primary source literature. Structured ecological survey of contrasting habitats/management.
Concerned only with the biomass and abundance of major invertebrate groups in moorland and acid
grasslands of the uplands. Does not consider effects of cattle grazing.
Coulson, J.C. and Whittaker, J.B. (1978). Ecology of moorland animals. In: O.W. Heal and D.F. Perkins,
eds.
Production ecology of British moors and montane grassland
s, Springer, Berlin, pp. 52–93.
Non-peer reviewed secondary literature. Structured ecological survey of contrasting habitats/management.
Concerned only with the biomass and abundance of major invertebrate groups in moorland and acid
grasslands of the uplands. Does not consider effects of cattle grazing.
Coulson, J.C. and Butterfield, J.E.L. (1985). The Invertebrate Communities of Peat and Upland
Grasslands in the North of England and Some Conservation Implications.
Biological Conservation
, 34:
197–225.
Peer reviewed primary source literature. Structured ecological survey of contrasting habitats/management.
No information provided on cattle grazing of moorlands. Emphasis on the contrasts in invertebrate
assemblages between acid grasslands, heather moorland and blanket bog.
Crofts, A. and Jefferson, R.G. (eds) (1999).
The Lowland Grassland Management Handbook 2nd edition
.
English Nature/The Wildlife Trusts.
Published report reviewing primary and secondary literature on grassland management. Includes compendium
of existing knowledge of grazing management for grasslands and provides many summary tables on
appropriate stocking densities for cattle on these habitats. Relevant to information for Scottish grasslands.
Curry, J.P. (1994).
Grasslands invertebrates. Ecology, influence on soil fertility and effects on plant growth
.
Chapman and Hall, London, pp. 424.
Published book reviewing primary and secondary literature on grassland invertebrates, including general
interactions with grazing animals.
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)
Dennis, R. (1999). The importance of extensive livestock grazing for woodland biodiversity: traditional
cattle in the Scottish Highlands. In: M.W. Pienkowski and D.G.L. Jones, eds.
Managing Farmland of high
nature conservation value: policies, processes and practices
, European Forum on Nature Conservation and
Pastoralism, pp. 62–66.
Non-peer reviewed secondary literature. Anecdotal comments in discussion/essay on the role of cattle in
the management of hill and woodland pastures in the highlands of Scotland. Many benefits for vegetation
and birds are described for grazing cattle at low stocking densities in these habitats but there is no scientific
validation of these statements. Neither is there scientific support for the recommendation to use traditional
cattle breeds for these low intensity grazing systems.
Dennis, P. (2003). Sensitivity of upland arthropod diversity to livestock grazing, vegetation structure and
landform.
Journal of Food, Agriculture and Environment
, 1, 301–307.
Peer reviewed partly primary source literature, partly review. Effects of cattle mixed with sheep investigated
only on
Nardus
-dominated of three acid grassland types. Full experimental design comprised treatments of
livestock species x target vegetation height with an ungrazed control, replicated but with random allocation
of sward height not livestock treatments to plots. Higher stocking density and cattle/sheep mix compared
with sheep only reduced numbers of insect herbivores, web-spinning spiders and removed both larger
beetles and those beetle species associated with a build up of plant litter. Concluded that cattle mechanically
disturb spider webs because they do not avoid tussock patches as is the case for sheep. Cattle possibly
compact soil and reduce its suitability by packing down crevices and air spaces that the larvae of large
beetles depend upon.
Dennis, P. et al. (1997). The response of epigeal beetles (Col.: Carabidae, Staphylinidae) to varied
grazing regimes on upland
Nardus stricta
grasslands.
Journal of Applied Ecology
34, 433–443.
Peer reviewed primary source literature. Effects of cattle mixed with sheep investigated on
Nardus
-dominated
grassland. Full experimental design comprised treatments of livestock species x target vegetation height with
an ungrazed control, replicated but with random allocation of sward height not livestock treatments to plots.
About one third of variability in beetle species assemblages was ascribed solely to differences in grazing
species or stocking density. Landform determined another third of the species composition, and an interaction
between these two factors the remaining variability. Different species were associated with cattle/sheep,
sheep and ungrazed treatments and the authors conclude that a mosaic derived from rotational and mixed
grazing would support the greatest number of species.
Dennis, P., Young, M.R. and Gordon, I.J. (1998). Distribution and abundance of small insects and
arachnids in relation to structural heterogeneity of grazed, indigenous grasslands.
Ecological Entomology
,
22, 253–264.
Peer reviewed primary source literature. Effects of cattle mixed with other grazing animals investigated only
on
Nardus
-dominated of three acid grassland types. Full experimental design comprised treatments of livestock
species x target vegetation height with an ungrazed control, replicated but with random allocation of sward
height not livestock treatments to plots. Money spiders, small beetle species and plant bugs all significantly
increased in taller sward treatments, for certain species, grazed by sheep rather than cattle and sheep.
A two-year ungrazed treatment yielded the highest densities for many of these arthropods.
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Dennis, P., Young, M.R. and Bentley, C. (2001). The effects of varied grazing management on epigeal
spiders, harvestmen and pseudoscorpions of
Nardus stricta
grassland in upland Scotland.
Agriculture,
Environment and Ecosystems
, 86, 39–57.
Peer reviewed primary source literature. Effects of cattle mixed with other grazing animals investigated
only on
Nardus
-dominated of three acid grassland types. Full experimental design comprised treatments of
livestock species x target vegetation height with an ungrazed control, replicated but with random allocation
of sward height not livestock treatments to plots. Three types of sampling used to assess spider assemblages.
Overall, densities of web spinners were higher in less grazed or ungrazed and in sheep rather than cattle
and sheep for a specific sward height.
Dennis, P., Aspinall, R.J. and Gordon, I.J. (2002). Spatial distribution of upland beetles in relation to
landform, vegetation and grazing management.
Basic and Applied Ecology
, 3, 183–193.
Peer reviewed primary source literature. Effects of cattle mixed with sheep investigated on
Nardus
-dominated
grassland. Full experimental design comprised treatments of livestock species x target vegetation height with
an ungrazed control, replicated but with random allocation of sward height not livestock treatments to plots.
Aggregations of beetle species were selected to represent the variability of all beetles sampled across the
experiment indicated strong associations with particular treatments or site characteristics at greater scale than
the experimental treatments. Larger, clumped distributions of
Calathus melanocephalus
on warm, insolated
slopes represented species typical of fertile lowland pastures, similar large clumps of
Pterostichus adstrictus
on cooler slopes of northern aspect represented moorland species. Two species had aggregations of the
same dimansions as the experimental treatments, the large beetle,
Carabus problematicus
, was clearly
restricted to sheep rather than cattle and sheep treatments, whilst
Olophrum piceum
occurred solely within
the ungrazed treatment characterised by the high proportion of plant litter.
Drake, C.M. (1995). The effects of cattle poaching on insects living at the margin of the River Itchen,
Hampshire.
British Journal of Entomology and Natural History
, 8, 165–169.
This paper looks at the effects of cattle poaching on the insect life of a chalk stream in England. It concludes
that cattle grazing can have both positive and negative effects on invertebrate communities of streams and
rivers. Positive effects are the promotion of a diverse fauna due to trampling. Negative effects are the
damage done to specialised beetle fauna of stony rivers. This paper tries to address what the best
management practices should be for chalk streams. It concludes that on balance the presence of cattle does
more harm than good in terms of invertebrates.
Duffey, E. et al. (1974).
Grassland Ecology and Wildlife Management
. Chapman and Hall, London.
Published book reviewing primary and secondary literature.
English Nature (2001). The Upland Management Handbook. English Nature, Peterborough.
Published report reviewing primary and secondary literature on upland management. Includes compendium
of existing knowledge of grazing management and provides many summary tables on appropriate stocking
densities for cattle on different habitat types, where information is available in the literature.
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)
Esselink, P. et al. (2000). The effects of decreased management on plant-species distribution patterns in a
salt marsh nature reserve in the Wadden Sea.
Biological Conservation
, 93, 61–76.
This was a survey based approach on a single salt marsh designed to link the distribution of cattle to that
of vegetation as a means of designing appropriate restoration measures for ungrazed salt marsh. Cattle
grazing with low to moderate stocking levels (0.47 cattle ha
–1
) allowed selective grazing and induced a
vegetation of enhanced botanical and structural diversity.
Eyre, M.E. et al. (1989). Ground beetles and weevils (Carabidae and Curculionidae) as indicators of
grassland management practices.
Journal of Applied Entomology
, 107, 508–517.
Peer reviewed primary source literature. Structured ecological survey of contrasting habitats/management.
General relationships between groups of beetle species and grassland types, defined by management
intensity but not with specific emphasis on the relative effects of cattle grazing.
Gander, A. et al. (2003). Habitat use by Scottish Highland cattle in a lakeshore wetland.
Bulletin of the
Geobotanical Institute ETH
, 69, 3–16.
This was a very small, unreplicated study of the distribution of grazing by highland cattle on a species-rich
wetland community that had previously been mown. It indicates that cattle have a preference for certain
vegetation
(Phalaris arundinacea
>
Carex
spp. >
Cladium mariscus)
and that there was a net transfer of
nutrients from wetter areas to the dry areas where the cattle rested.
Gibson, C. et al. (1992a). The response of invertebrate assemblies to grazing.
Ecography
, 15, 166–176.
Peer reviewed primary source literature but the study did not include cattle grazing. It is possible to infer
some general effects of grazing management from this study of non-bovine livestock.
Gibson, C.W.D., Hambler, C. and Brown, V.K. (1992b). Changes in spider (Araneae) assemblages in
relation to succession and grazing management.
Journal of Applied Ecology
29, 132–142.
Peer reviewed primary source literature but the study did not include cattle grazing. Reduced grazing
increased the architecture of vegetation, and the benefits for web-forming spiders may be applicable to
cattle grazing too.
Gimingham, C.H. (1972).
Ecology of heathlands
. Chapman and Hall, London.
Authoritative, published book that reviews the primary and secondary literature concerned with heather
moorland. General effects of grazing inferred from non-bovine livestock.
Gimingham, C.H. (1995). Heaths and moorland: an overview of ecological change. In: D.B.A. Thompson,
A.J. Hester and M.B. Usher, eds.
Heaths and Moorland: Cultural Landscapes
. HMSO, Edinburgh. pp. 95–101.
Authoritative, published book that reviews the primary and secondary literature concerned with heather
moorland. No specific reference to cattle grazing in this context.
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)
Grant, S.A. et al. (1982). Effects of season and level of grazing on the utilisation of heather by sheep.
3. Longer-term responses and sward recovery.
Grass and Forage Science
37, 311–326.
Peer reviewed primary source literature. Pseudo-replicated experiment (large plots without true random
allocation of treatments). General effects of grazing inferred from non-bovine livestock.
Grant, S.A. et al. (1985). Comparative studies of diet selection by sheep and cattle: the hill grasslands.
Journal of Ecology
73, 987–1004.
Peer reviewed primary source literature investigating differences in foraging ability between sheep and
cattle. Sheep were much more selective in their diet, and were better able to select preferred species than
cattle, which were much more indiscriminate in their diet selection. Consequently, cattle also ingested a lot
more dead material than sheep. The cattle also grazed higher up the sward than sheep.
Grant, S.A. et al. (1987). Comparative studies of diet selection by sheep and cattle: blanket bog and
heather moor.
Journal of Ecology
, 75, 947–960.
Peer reviewed primary source literature investigating the diet composition of sheep and cattle that grazed at
different times of the year on both blanket bog and heather moorland. Cattle were less discriminating grazers
and on heather moor tended to remove more shoot length and cause greater damage to heather. It was
concluded that it was not appropriate to graze blanket bog with cattle due to the risk of severe poaching.
Cattle may be useful in maintaining a satisfactory balance between
Calluna vulgaris
and
Molinia caerulea
on the fringes of blanket bog provided there are drier areas available.
Grant, S.A. et al. (1996a). Controlled grazing studies on
Nardus
grassland: effects of between-tussock
sward height and species of grazer on
Nardus
utilisation and floristic composition in two fields in Scotland.
Journal of Applied Ecology
33, 1053–1064.
Peer reviewed primary source literature. Pseudo-replicated experiment (large plots without true random
allocation of treatments). Effects of grazing by sheep, cattle and goats on
Nardus
swards investigated and
it was shown that cattle or goat grazing significantly reduced
Nardus
cover compared with sheep grazing
when the same intertussock sward height was maintained.
Grant, S.A. et al. (1996b). Controlled grazing studies on
Molinia
grassland: effects of different seasonal
patterns and levels of defoliation on
Molinia
growth and responses of swards to controlled grazing by cattle.
Journal of Applied Ecology
33, 1267–1280.
Peer reviewed primary source literature. Pseudo-replicated experiment (large plots without true random
allocation of treatments). Cattle were grazed to two levels of
Molinia
utilisation on
Molinia
-dominated grass.
At a 66% utilisation rate over six years the cover of
Molinia
in the sward was reduced by 86%.
Grayson, F.W. (1999). The use of native livestock breeds in restoring grazing to limestone grasslands
abandoned by agriculture. In: M.W. Pienkowski and D.G.L. Jones, eds.
Managing farmland of high nature
conservation value: policies, processes and practices
. European Forum on Nature Conservation and
Pastoralism. pp. 62–66.
This paper relates the story of the restoration of grazing on the limestone hills around Morcambe Bay in
England. The area was abandoned as a grazing resource many years ago and became dominated by a
mix of very coarse grassland and scrub. These was concern that the proportion of grassland was in serious
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Scottish Natural Heritage Commissioned Report No. 203 (
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)
decline because of encroachment by scrubland. Within the area, there were a number of nature reserves,
managed by various agencies. Restoration of grazing was implemented, in partnership with local farmers
who could bring the required stock management skills which the site managers lacked. The reintroduction
of grazing by cattle was made financially viable because of the Countryside Stewardship Scheme.
Native breeds of cattle were used and meat from these animals has been marketed as a niche product
directly to the public which has been to the financial benefit of the system.
Hatch, D.J. et al. (2004). Ammonium-N losses from Agriculture. Agriculture and the Environment,
Water Framework Directive in Agriculture.
Proceedings of SEPA/SAC biennial conference, Edinburgh
24–25 March 2004
.
Some of the environmental hazards associated with keeping cattle are highlighted in this report. Pollution of
watercourses by ammonium N are related to spreading of slurry and manures, runoff from tracks used by
cattle and from farmsteads and direct access by cattle to streams and watercourse. Many of these problems
are more likely to be associated with high intensity agriculture, but their potential effects need to be borne
in mind when considering livestock systems.
Hester, A.J. (1996). Overgrazing in Upland Habitats: A literature review. Report for the Countryside
Council for Wales.
Unpublished report reviewing primary and secondary literature with relevance to grazing practices in the
Welsh uplands. General effects of grazing inferred mainly from studies of non-bovine livestock.
Hodgson, J. et al. (1991). Comparative studies of the ingestive behaviour and herbage intake of sheep
and cattle grazing indiginous hill plant communities.
Journal of Applied Ecology
, 28, 205–227.
This peer reviewed study investigated the ingestive behaviour and herbage intake of dry cattle and sheep
grazing six different habitats, viz. sown grassland,
Agrotistis/Festuca
grassland,
Nardus
-dominated grassland,
Molinia
-dominated grassland and two dwarf shrub communities,
Calluna vulgaris–Eriophrum vaginatum
blanket bog and
Calluna vulgaris
moor. The results suggested that cattle were less selective in their diet than
sheep and therefore were able to remove proportionately greater amounts of poorer quality vegetation.
It was also suggested that sheep were less able to adapt to tall swards than cattle. Sheep grazed to a
greater depth than cattle and were more selective in the diet they ingested.
Howard, C.L. and Wright, I.A. (1994). Effects of mixed grazing by cattle and sheep on
Nardus stricta
dominated grassland. In: R.J. Haggar and S. Peel eds.
Grassland Management and Conservation,
Occasional Symposium No. 28, British Grassland Society
. pp. 292–294.
Summary of an experiment in which sheep only or mixed cattle plus sheep grazed on
Nardus
-dominated
grassland. The liveweight gains of the sheep when they grazed along with cattle were higher than when
they grazed as the sole species.
Hulme, P.D. et al. (1999). The effects of controlled sheep grazing on the dynamics of upland
Agrostis–
Festuca
grassland.
Journal of Applied Ecology
, 36, 886–900.
Peer reviewed primary source literature. Experimental design (treatments of habitat x sheep stocking density
or target vegetation structure, appropriate control, replicated with random allocation of treatments to plots).
General effects of grazing inferred from an experimental study of sheep grazing at three sward heights on
Agrostis–Festuca
grassland.
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Humphrey, J.W. and Patterson, G.S. (2000). Effects of late summer cattle grazing on the diversity of
riparian pasture vegetaion in an upland conifer forest.
Journal of Applied Ecology
, 36, 986–996.
Peer reviewed primary source literature. Structured ecological survey of contrasting habitats/management.
Investigated the contribution of cattle to plant species diversity of flush vegetation, acid grassland and rush
pasture in upland forests of Northern Scotland. Cattle were successful in preventing a further decline in
species richness on all three habitats in which previous fencing and tree planting had led to rank vegetation
dominated by competitive plant species. Anecdotal conclusion that should cattle be used to management
vegetation fenced in by forestry, such areas must be large enough to allow free-ranging and the development
of a mosaic, and also to avoid localized detrimental effects.
Kirby, P. (1992).
Habitat management for invertebrates: a practical handbook
. RSPB/Joint Nature Conservation
Committee, Sandy, Bedfordfordshire.
Published report reviewing primary and secondary literature. Anecdotal comments in discussion suggested
that cattle as opposed to sheep grazing in woodland, grassland, lowland heaths, freshwater wetlands and
coas