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Animal Science Papers and Reports vol 28. (2010) no. 4, 315-334
Institute of Genetics and Animal Breeding, Jastrzębiec, Poland
Grazing as a tool to maintain biodiversity
of grassland – a review
Ewa Metera1, Tomasz Sakowski1*,
Krzysztof Słoniewski1, Barbara Romanowicz2
1 Polish Academy of Sciences Institute of Genetics and Animal Breeding,
Jastrzębiec, 05-552 Wólka Kosowska, Poland
2 Compassion in World Farming, River Court, Mill Lane,
Godalming, Surrey GU7 1EZ, UK
(Received October 2, 2009; accepted September 20, 2010)
The intensication of agriculture has a great inuence on grassland, resulting in the disappearance of
many plant and animal species and changing open landscape. Sustainable farming practices, which
use farm animal grazing, are seen as a potential solution to continued biodiversity loss resulting
from over- or undergrazing. In the article the inuence of grazing animals on grassland biocenoses
and their use in active biodiversity protection are reviewed based on over 100 references. It is
concluded that animal grazing can be a tool to maintain or restore biodiversity of open landscape
and contribute to the aesthetic and leisure importance of grassland. The successful use of grazing
for environment protection and biodiversity enhancement requires careful planning and should be
adapted to local conditions. A deep understanding of the relationship between herbivores, plant,
and small animal communities and the abiotic environment is essential. Therefore, there is a need
for comprehensive research programmes in the area of extensive grazing, combining expertise from
ecology, botany, agronomy, animal production and rural economics. The research should include
both eld experiments and development of appropriate models, allowing for the design of agro-
environmental schemes aimed at the protection of grassland biocecenoses.
KEY WORDS: biodiversity / grassland / grazing / herbivores / landscape protection
*Corresponding author: t.sakowski@ighz.pl
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Introduction
Grassland is an important agroecosystem, constituting more than 30% of
agricultural land in Central Europe [Zimkova et al. 2007] and 20-22% of the total area
used in agriculture in Poland [Sawicki 2006, European Commision 2009]. Grassland
plays an important role in European animal production, particularly in production of
milk [Smit et al. 2008]. As well as their contribution to food and feed production,
pastures and meadows form specic landscape and are a habitat for many species of
plants and animals, resulting in a high biodiversity referring to all living organisms
existing and interacting within an ecosystem [Vandermeer and Perfecto 1995, van
Wieren and Bakker 2008].
In agroecosystems, biodiversity performs a variety of ecological services beyond
the production of food and feed, including the recycling of nutrients, regulation of
microclimate and local hydrological processes, suppression of undesirable organisms
and detoxication of noxious chemicals [Altieri 1999]. There is growing evidence that
the level of internal regulation of functions in agroecosystems is largely dependent
on the level of plant and animal biodiversity present. Thus, biodiversity of grassland
is important not only as a tool to protect plant and animal communities, but also in
sustaining their agricultural productivity.
The intensication of agriculture, largely driven by economic factors, has a
major inuence on grassland. In general, extensive meadows and pastures are less
productive and give crop with a lower net energy content compared to those managed
intensively. Thus, farmers expect to achieve quicker and better results with intensive
practices, such as frequent fertilization. Agricultural activities such as tillage, drainage,
intercropping, rotation, grazing and extensive use of pesticides and fertilizers have
signicant implications for wild species of ora and fauna [McLaughlin and Mineau
1995]. In consequence, the overly-intensive use of grasslands is the main reason for
the disappearance of many plant species [Bohner 2007]. Gough and Grace [1998]
and Marty [2006] also highlight, that an increase in grassland productivity results in
a decline in number of plant species in many habitats. Consequently, a remarkable
decrease in the range and abundance of many species associated with farmland has
been reported across Europe. Sustainable farming systems such as extensive or
organic farming, with the use of farm animal grazing, are seen as a potential solution to
continued biodiversity loss. It has been shown that organic and low-input production
systems support greater genetic and biotic diversity of agricultural ecosystems [Duelli
1997, Bartoszuk et al. 2001, Hansen et al. 2001, Bohner 2007]. In regions with rich
soils, the number of species on organic elds has been found to be up to 10 times
higher compared to conventional elds [Heineken 1990].
Extensively managed pastures and meadows are of crucial importance for
grassland biodiversity across Europe. Unfortunately, biodiversity of such biocenoses
is currently threatened either by intensive use or by abandonment [Bartoszuk et al.
2001, Dolek and Geyer 2002, Poschlod and Wallis de Vries 2002]. In many areas
of Europe, low grazing pressure leads to the creation of unexploited areas that are
E. Metera et al.
317
progressively covered with shrubs [Bailey et al. 1998]. Soussana and Duru [2007]
state that within 20 years, permanent grassland and pastures in Western Europe have
declined by 12%. This phenomenon has also been observed in Poland, where, as a
result of the decreasing numbers of cattle and horses, fewer of them are being grazed
on grasslands [Jankowska-Huejt 2007]. This is particularly the case in areas with
unfavourable agricultural conditions. The result is a succession of undesirable plant
communities leading to a biodiversity decline.
Extensive farming which uses animal grazing, can be a tool to maintain or restore
open landscapes, and also has a benecial effect on adjacent wild ecosystems [Bartoszuk
et al. 2001, van Braeckel and Bokdam 2002a, Dumont et al. 2007, Isselstein et al. 2007,
Jankowska-Huejt 2007, Scimone et al. 2007, Wallis De Vries et al. 2007]. Conversion
of intensively managed farms to organic methods of management is also benecial to
nature conservation [Haggar and Padel 1996]. A mixed farming system with a high
proportion of grassland habitats is likely to maintain a number of important farmland
bird populations in many countries including Poland [Sanderson et al. 2009]. The
importance of extensive grassland use for biodiversity and landscape conservation is
the main reason for the substantial support of these practices in the form of subsidy
payments, through EU and national government legislation [Hole 2005].
The effect of grazing animals on grassland biocenoses
Grazing animals can affect an ecosystem through defoliation, treading and leaving
excreta [Warda and Rogalski 2004, Duncan 2005, Wasilewski 2006]. The transport of
seeds is another signicant way in which grazers can inuence plant diversity [Olff
and Ritchie 1998]. Natural fertilization and transport of nutrients in animals’ excreta is
also important for grassland and adjacent biocenoses which may be used by herbivores
for feeding and resting. It may be assumed that wild plants are adapted to herbivores
since they have evolved together. However, the intensity of defoliation, treading and
natural fertilization in farming landscapes may exceed the levels occurring in natural
systems, thus adverserly affecting grassland biocenoses.
Defoliation is the main way in which herbivores affect plant communities.
Periodic defoliation is vital for controlling succession of plants [Rook et al. 2004].
Intensive defoliation, on the other hand, inhibits the development of trees and shrub
seedlings and supports mass growth of grasses [van Braeckel and Bokdam 2002a].
Unselective defoliation on a massive scale stimulates the growth of short plants, thus
creating and maintaining open landscapes such as pastures and meadows. However,
herbivores usually defoliate selectively. Selective defoliation encourages the growth
of unpalatable tall plants and supports the creation of a mosaic landscape structure
[Warda and Rogalski 2004]. Rook et al. [2004] concluded that the main mechanism
through which grazing animals inuence pastures is their dietary selection, which in
consequence creates and maintains the structural heterogeneity of pasture swards.
Grazing as a tool to maintain biodiversity of grassland
318
Treading can have both a positive and negative effect on pasture soil. Treading
or trampling creates gaps in the sward and has a positive effect on the establishment
of annual and bi-annual species. [Van Braeckel and Bokdam 2002]. Treading of the
soil surface creates gaps thus allowing seeds to sprout, which in effect speeds up the
growth of grasses, and eventually prevents soil erosion [Warda and Rogalski 2004].
The extent of that impact depends largely on the size of grazing animals and the number
of individuals per surface area. For example, Bartoszuk et al. [2001] suggest that size
is an advantage of using cattle for pasture conservation, as heavy animals prevent the
growth of weeds by trampling and disturbing the soil with their hoofs. According to
Vavra [2005], grazing animals can protect specic plant seeds by churning the soil and
creating mulches which cover them. On the other hand, trampling may reduce stream
bank stability and increase soil erosion [Kauffman et al. 1983, Vavra 2005]. The risk
of erosion increases when a soil is wet, when animals cut the canopy very short (less
than 20 mm) or when stocking rate is too high [Russell et al. 2001].
Trampling is potentially dangerous for groundnesting birds’ nests and animal
burrows. However, the ornithological studies in the Biebrzanski National Park in
Poland have indicated that extensive grazing of cattle contributed to the improvement
of nesting conditions. The positive effect of grazing was a result of the creation of a
habitat structure optimum for birds. Moreover, the presence of grazing cattle reduced
the pressure of small predators on nests and nestlings. The positive effects far exceeded
nest losses caused by the cattle themselves [Mazurek 2002, 2003].
Animal manure plays an important role in creating and preserving biological
diversity. The excreta produced by herbivores during grazing act as a natural fertilizer
and inuence seed distribution. Manure is a rich source of nutritive substances
essential for green biomass growth. The dispersal of faeces results in species and
structural diversity of ora [Guziak and Lubaczewska 2001, Peco et al. 2006].
However, intensive grazing can also cause over-fertilization of pastures, disturbing
organic matter and the nutrient circulation balance, thus negatively inuencing the
biodiversity of a whole ecosystem. For example, a decrease in wader populations on
mown and grazed peat grassland is observed when the farmland is drained and heavily
manured [Dyrcz et al. 1985, Kleijn et al. 2001].
Factors modifying the inuence of grazing on the environment
As already mentioned, the way in which herbivores utilize plants differs between
species. This is demonstrated by the different browsing strategies and preferential
grazing of different plant species. Van Braeckel and Bokdam [2002] divide large
herbivores into three functional groups. The rst group, the grazers, includes cattle,
horses and other social herbivores capable of digesting the plant cell wall bre
efciently. The second group is browsers, which include elk and roe deer. They are
very selective, solitary herbivores, which mainly digest the cell content of plants. The
third group consists of the intermediate feeders (e.g. red deer and European bison).
E. Metera et al.
319
They are social herbivores that can switch between the grazing and browsing strategy
[Hofmann 1989]. We will focus on the role of grazers, as the majority of grazing farm
animals belong to this category.
Animal species differ in their preference for taking various plants, im the order
of selection of species taken and in height of the cut made [Abaye et al. 1994, Bailey
1999]. Due to the diverse feeding behaviour and feed preferences, the impact on the
area grazed differs between species. For example, Bartoszuk et al. [2001] pointed out
that cattle prefer taller grasses and other plants, whereas horses (Polish Konik) select
the shorter sward. Cattle prefer the reproductive parts of plants whereas sheep show
preference for vegetative parts. Compared to cattle, horses are more inclined to take
brous grasses. Furthermore, they can bite closer to the ground because of their teeth
structure [Dumont et al. 2007]. Cattle often utilize grassland selectively by grazing
some areas more intensively than the other, resulting in local overgrazing [Coughenour
1991]. Goats are less selective than other farm ruminants in the species of plant eaten
[Bartoszuk et al. 2001]. Sheep and goats generally need more energy in relation to
their gut capacity than cattle, and they have, therefore, to select plant parts with higher
nutritive value (owers, pods, shoots) - Rook et al. [2004]. The degree of selectivity
of animals to the plants eaten depends also on sward composition and quality [Rook
et al. 2004, Dumont et al. 2007]. When the sward is rich in diverse species of ora,
animals tend to choose plants which meet best their nutritional requirements. When
the sward diversity is smaller, animals start to graze less selectively.
Interactions between herbivores and ecosystems are especially complex in the
case of free-ranging animals, as abiotic zones and successive stages of biocenoses are
of different attractiveness for foraging vs. resting animals. For example, oodplains
with short grass swards are preferred foraging habitats by grazers, whereas woodland
on nutrient-poor fens and bogs are nonattractive. Short vegetation in minerotrophic,
base-rich fens occupies an intermediate position. Woodlands on uplands are a second-
choice foraging habitat but they may be preferred for resting. This differential use of
habitats generates nutrient transport between ecosystems [Van Braeckel and Bokdam
2002]. The ability of herbivores to move between different ecosystems is especially
important when they are used in order to protect or conserve natural landscapes.
Rogalski et al. [2001] quote several examples of the way in which species of
grazed animals affect the botanical composition of pasture swards. Due to selective
biting, valuable grass species such as perennial ryegrass (Lolium perenne) were
found to disappear from pastures grazed by cattle. This grass species also decreased
in abundance on pastures grazed by sheep. L. perenne and smooth meadow grass
(Poa pratensis) decreased in abundance on horse grazed pastures. The declining grass
species were replaced mainly by orchard grass (Dactylis glomerata). When goats
were grazed, meadow fescue (Festuca pratensis) gradually declined and was replaced
by D. glomerata and L. perenne, which became dominant in the sward. Sheep, and
especially horse grazing, reduced the abundance of white clover (Trifolium repens)
Grazing as a tool to maintain biodiversity of grassland
320
the abundance of which was positively affected by goat grazing. Generally, grazing
animals increased the abundance of herb species in the sward.
Grant et al. [1985] compared grazing sheep and cattle and found that the two
species differed signicantly in all major aspects of their diet. Sheep diets contained
more forbs and less grass ower stems than those of cattle. The differences between
sheep and cattle diets were explained by a difference in the height at which the
animals bit the sward, related to the distribution of plant species within the sward
canopy. Other important differences included the greater ability of sheep to select
from ne-scale mixtures; and the greater readiness of cattle to graze on tall, more
brous components.
Grazing can be useful in controlling valueless grasses, as Dumont et al. [2007]
showed in the case of nard (Nardus sp.). Cattle grazing reduced the area covered by this
grass by 30% in ve years. During the same period, grazing by sheep decreased its area
by 80%. It was also shown that the share of same grass was more greatly reduced after
six years of grazing by horses then in the same period of grazing by cattle. Moreover,
horses keep grassy areas short, at a height of less than 4 cm, because they can bite closer
to the ground, due to their teeth structure [Dumont et al. 2007]. Cattle prefer taller
grasses, at a height between 9 and 16 cm. The above comparison indicates that horses
can be used to reduce tall grass vegetation successfully. This has in fact been shown in
practice, both in France and in the Netherlands [Dumont et al. 2007].
It is not only animal species, but also breed that affects the way in which a sward
is grazed. Rook et al. [2004] suggested that the differences in question are primarily
a result of differences in body size and gave many examples of such variations. For
example, French dual-purpose steers (Meuse-Rhine-Yssel) were more selective than
Hereford steers, and Salers heifers were less selective than Limousine heifers. The
quoted authors found also that Aberdeen Angus steers with the “small” genotype were
more selective that those with “large” genotype, which conrms that size of animals
is important in determining grazing preferences.
Studying commercial and traditional livestock breeds, Dumont et al. [2007] found
some differences in their grazing strategy. North Devon steers expressed a greater
preference for tall grass-forbs than Charolais × Holstein crossbreds, but generally
traditional breeds appeared to be less selective than commercial ones. The age and
physiological status of the animal also alters its feeding preferences. Young animals
and pregnant or lactating females prefer forages with higher nutritive value and so are
more selective when grazing [Rook et al. 2004].
The effect of grazing on the environment depends on regional variation in major
habitat characteristics, such as soil fertility and availability of water. There is evidence
that differences occur between herbivore species in their preference for pasture soil
type. For example, horses (Polish Konik) prefer plants typical of dry soils [Bartoszuk
et al. 2001], whereas cattle will readily graze on plants from both dry and humid soils
[Wasilewski 2006]. Consequently, free-ranging animals move between biocenoses,
depending on time of day or season, seeking for preferred food or convenient resting
E. Metera et al.
321
place. Large herbivores will use the nutrient-rich oodplain (and peat zone) as summer
foraging habitats and the uplands as winter habitats. In the absence of oodplains,
their function may be substituted by fertilized upland sites or by supplements. Winter
feed supplementation or shelter may substitute a lacking upland site. In complete
successional mosaics, animals shift daily and seasonally between grassland and
woodland for foraging and resting, respectively.
Peco et al. [2006] stressed that moderate grazing increases fertility of very poor
soils and promotes species richness at the local scale as well as vegetation cover,
which contributes to protecting the soil from erosion. It also improves the soil’s ability
to retain water, which is important for seed germination and seedling establishment in
environments where the main limiting factor for these processes is water. On the other
hand, animals grazed on sensitive soils can cause serious environmental damage. For
example, the exposure and maintenance of bare soil in the UK by grazing animals,
especially sheep, initiates erosion of sensitive soil, particularly in the uplands. When
initiated, erosion processes can be very difcult to stop, even when animals are
excluded from the area by fencing [Evans 1997]. This indicates that both the type
of grazed animals and the grazing intensity have to be carefully adjusted to local
conditions in order to achieve benecial results of grazing for biodiversity. Providing
that this is done, the inuence of grazing animals together with the spatial diversity
of soil and water conditions, supports development of rich, mosaic landscapes. The
mosaic landscape offers habitats for foraging and breeding for waders, waterfowl and
marsh birds [Haggar and Padel 1996]. Diversication of swards also ensures a variety
of niches for invertebrates, which are part of the birds’ diet. Moreover, birds such
as plovers and lapwings prefer clustered plants for egg laying and raising nestlings
[Guziak and Lubaczewska 2001].
The effect of grazing on the ecosystem depends on its intensity, and particularly
on livestock density. According to Scimone et al. [2007], grazing intensity generally
had profound effects on vegetation diversity, but the effect depended on site-specic
vegetation characteristics.
Extensive or semi-intensive grazing has a positive effect on biodiversity. Grazing
at a low stocking rate seems to have the potential to facilitate the restoration of diverse
swards and to support reasonable individual performances of the grazing animals
[Isselstein et al. 2005, Tallowin et al. 2005]. Verhulst et al. [2004] found the most bird
species in extensive grassland, whereas intensively grazed elds had lower species
numbers, and lower density and diversity. Based on these ndings, the authors suggest
that conservation efforts aimed at farmland birds should be focused on maintaining
extensive farming systems. Light grazing can increase species richness and the
abundance of wild animals, especially butteries, grasshoppers and ground-dwelling
arthropods [Wallis De Vries et al. 2007]. Moderate grazing can be a useful tool to
limit expansion of shrubs, as shown by Casasus et al. [2007] in the mountain pastures
of the Pyrenees, resulting in the enhancemetnt of the environmental and recreational
value of the area.
Grazing as a tool to maintain biodiversity of grassland
322
In the case of intensive grazing practices, the opposite effect can be expected.
Overgrazing affects soil properties resulting in reduced water inltration, less soil
moisture and fertility. It changes microbiological activity and increases soil erosion
[Czeglédi and Radácsi 2005, Thurow 2005]. High grazing pressure decreases plant
diversity, changes the botanical composition of the sward and can lead to the invasion
of undesirable plant species. For example, when grazing is intensive, bunch grasses
tend to be eliminated. Intensive grazing leads to an increase of short grasses and
annuals, which do not stimulate soil maintaining because of their poor root system.
There are many examples of the negative effect of intensive grazing on ecosystems
[Evans 1997, Lennon 1999, Czeglédi and Radácsi 2005]. The Project “Transhumans
for Biodiversity Conservation” revealed that overgrazing signicantly decreases the
number of endemic plant species [GEF 1999, Debayle 2004]. Lapointea et al. [2000]
presented another example, where an excessive number of grazing cattle was a major
factor responsible for the decline of duck populations throughout islands in South
Quebec (North America). Lennon [1999] describes damages done to fragile alpine
ecosystems in Australia by cattle and sheep grazing over the last century.
Undergrazing can be equally harmful for biodiversity as overgrazing. Undergrazing
leads to less stimulation and gradual loss of grazing-dependent endemic grasses and
legumes. It was found that long-term grazing abandonment can result in the loss of
more than 60% of grassland species [Peco et al. 2006].
One way of beneting from the different feeding preferences of animal species
is to graze them together – a practice called mixed grazing. Mixed grazing could be
benecial both for quality of forage and performance of grazing animals as shown
by Abaye et al. [1994] in simultaneous grazing of sheep and cattle. Extensive,
mixed grazing has been practiced for many centuries and has had profound effects on
landscape and biodiversity [Collins 1989].
Loucougaray et al. [2004] examined the effect of mixed grazing of horses and
cattle on the diversity of coastal grasslands in western France. These areas contained
diverse plant communities, ranging from hygrophilus through seasonally ooded,
meso-hygrophilus on slopes where the soil remains saline to mesophilus on higher
altitudes. Mixed grazing enhanced the development of rosette, sub-halophyte and
halophyte species in saline areas, and limited the strongly competitive couch grass
(Elymus repens) and creeping bent (Agrostis stolonifera). They concluded that mixed
grazing supports the creation of the most species-rich and structurally diversed swards.
The results indicate that mixed grazing can be used to manage plant diversity and
preserve endangered communities at the scale of grassland ecosystem.
Certain authors have stated that sheep and goats can graze together effectively,
and that goats may be used to improve pastures for sheep production [Del Pozo et al.
1998, Animut et al. 2005, Celaya et al. 2007]. The advantages of co-grazing of sheep
and goats are derived primarily from differences in their preferences for particular
plant species and parts, their ability or willingness to consume forages that are not
highly preferred and would have adverse effects on the other species, and physical
E. Metera et al.
323
capabilities to gain access to specic types of vegetation. Co-grazing of sheep and
goats illustrates the importance of browsers in many grazing systems and shows how
management practices can be employed to maintain or increase their prevalence and
vegetation diversity [Animut and Goetsch 2008].
Little research has been carried out into the co-grazing of cattle and pigs. However,
Stoegaard et al. [2000] and Sehested et al. [2004] have shown that the diversity of
plants on pasture is highest when grazing heifers alone, followed by mixed grazing of
heifers and sows. The lowest diversity was found when grazing sows alone.
Generally, mixed grazing can be used effectively in order to enhance plant diversity
and animal performance, but overly high density of animals or a bad selection of
species can be harmful to diversity of the habitat [Animut and Goetsch 2008].
Use of grazing animals for active biodiversity protection
Due to its inuence on the environment, animal grazing is used as a tool for
protection and restoration of biocenoses of high biological and cultural value. Grazing
is considered to be an important practice for the survival of many threatened plant
and animal species in Europe [Bignal et al. 1994, Poschlod and Wallis de Vries 2002,
Dolek and Geyer 2002]. The main role of animals grazed on threatened grasslands
is to control plant species richness. This is a critical issue in the conservation and
management of grassland biodiversity. In order to achieve the expected results,
the species of grazing animal and method of pasture management must be chosen
carefully whilst taking into account the local natural conditions and the conservation
goals of that particular area.
Numerous eld experiments on grassland plant communities have shown
that herbivores often, although not always, increase plant diversity. In most cases,
grazing was introduced as a prevention measure against the proliferation of shrubs.
Van Braeckel and Bokdam [2002b] studied Biebrzanski National Park (Poland) in
order to evaluate the effectiveness of cattle and horse grazing as a tool to prevent the
succession of undesirable plants. Their results show that grazing animals prevented
and limited the invasion of reeds, but did not restore desirable agglomerations of
sedges and mosses. This indicates that a major role of extensive grazing is to preserve,
not to restore desirable sward composition. They concluded that grazing of cattle,
horses and geese should be integrated with mowing once or twice a year in order to be
effective in maintaining and preserving the unique landscape and biological richness
of the Biebrza Valley basin.
Hoffmann [2002] described the successful use of cattle, horses and sheep in
Flanders to halt the expansion and succession of shrub species. Warda and Rogalski
[2004] have also conrmed the positive effect of grazing on open biocenoses. Cattle
and horse grazing on saline meadows in the Swina valley (Poland) contributed to
the protection of 21 plant species growing there as well as the protection of rare bird
habitats.
Grazing as a tool to maintain biodiversity of grassland
324
Many authors have described the use of sheep grazing for nature conservation,
both in the uplands and in the mountains [Nowakowski et al. 1999, 2000] as well as in
the lowlands [Groberek 2005]. Sheep grazing inhibited the succession of undesirable
plants and had a positive effect on the enrichment and diversity of oristic communities
[Gordon 1990, Harnett 1995, Gutman et al. 1997, Niznikowski 2003]. Sheep were also
successfully used for grassland conservation in France [Debayle 2004]. Harris [2002]
reported that use of sheep was successful in the conservation of habitats for endemic
plants, such as the Scottish primrose (Primula scotica) on the Orkney Islands.
As already mentioned, grazing can slow down the expansion of shrubs on meadows
and pastures, but is not enough to prevent it completely or to reverse succession. In
order to maintain open landscapes, grazing must be combined with other practices.
Bartoszuk et al. [2001] note that there is no meadow management without grazing
and no pasture management without mowing, as these two practices must compliment
each other. In order to maintain and preserve biodiversity of open landscapes, a
combination of practices including grazing, mowing, and reed and wood cutting were
suggested by van Braeckel and Bokdam [2002b].
Some authors emphasize the usefulness of local, indigenous breeds for the
protection of valuable landscapes through extensive or semi-intensive grazing
[Bartoszuk et al. 2001, Wasilewski 2002, 2006]. The advantages of using these
breeds for the above mentioned purpose include their resistance to difcult climatic
and environmental conditions and ability to utilize low quality feed. Moreover, they
have a calm temperament, with good health and resistance to diseases and parasites,
including insects, and show good reproductive performance. When horses are used for
such a purpose, then light breeds, such as the Konik Polski, which are well adapted
to harsh conditions, should be preferred over heavier working horses [Bartoszuk et
al. 2001]. Groberek [2005] reported that sheep of the native Polish breed Wrzosowka
(Hether Sheep) were successfully used to prevent undesirable plant succession in
lowland areas.
Opinions about the use of mixed grazing for environmental protection are not
consistent. Some authors claim that mixed grazing can lead to restoration of plants
diversity, while others believe that it reduces the biodiversity of a sward.
Generally, many published results suggest that the introduction of large herbivores
into natural grasslands may help to maintain and enhance its botanical diversity.
However, in the examples published, grazing was not always the correct method for
vegetation management, as demonstrated by Kohyani et al. [2008] in coastal dune
habitats. Thus, the existing scientic evidence indicates that scale and environmental
site conditions are both to be considered when grazing animals are introduced.
The successful use of grazing for environmental protection and biodiversity
enhancement requires careful planning. In all cases, the choice of breed, animal
density and pasture management should be suited to local conditions and conservation
goals in order to achieve the desired results. There is no universal solution, and
grazing programmes should be tailored to local conditions. Usually, such programmes
E. Metera et al.
325
are developed by using examples of similar work carried out in practice, and then
accommodated through trial and error. A prerequisite for the development of viable
programmes is a deep understanding of the relationship between herbivores, plant and
animal communities and the abiotic environment. Moreover, predicting the effects
of grazing on ecosystems requires modelling [Van Oene et al. 1999]. The models
used should include the spatio-temporal distribution of herbivores and plant species,
across-zone inuences, successional stages and subsequent responses. Simulation
models should be developed to calculate the effects of grazing and other management
on vegetation succession and related ecosystem properties. The models can facilitate
the comparison of different management practices only if they are reliable. This is a
key issue for environment conservation experts. The development and testing of such
models is of crucial importance and requires much research.
Socio-economic aspects of extensive grazing
Grassland is vital for health and welfare of farm ruminants and for horses, as
well as for milk production [Smit et al. [2008]]. Plant species diversity inuences
both the performance of livestock grazing on pastures, and the quality of the raw
animal products. On the other hand, grazing animals impacts pasture biodiversity in
the whole meaning of the term (i.e. of plants, animals and insects).
The positive inuence of sward diversity on the performance of grazing animals
was conrmed by Soder et al. [2007] and Edouard et al. [2007]. The presence of herbs
and specic plant species in the sward positively inuences the fatty acid composition
of milk and meat, with a particular inuence on health promoting substances, such as
polyunsaturated fatty acids. The greatest advantage of pasture-based milk and meat
production is obtaining a product with higher content of unsaturated fatty acids and
vitamins, known to be benecial for human health [Jahreis et al. 1997, Enser et al.
1998, Bugaud et al. 2001, Martin et al. 2004, Couvreur et al. 2006, Strzałkowska et
al. 2009abc]. Pastushenko et al. [2000] have shown that pasture feeding in organic
beef and veal production improved the quantity and composition of polyunsaturated
fatty acids of meat. Wood et al. [2003] reviewed the information about fatty acid
composition of pork, beef and lamb and concluded that feeding grass elevates the
content of polyunsaturated fatty acids and vitamin E. Raziminowicz et al. [2006] has
shown that beef from pastured cattle is rich in n-3 fatty acids and has a better ratio
of n-6/n-3 fatty acids than beef from other origins. Adnoy et al. [2005] conrmed
that meat from lambs raised in extensive systems on unimproved mountain pastures
had signicantly better chemical content and sensory quality compared to meat from
lambs grazing on cultivated lowland pastures. Fraser et al. [2009] reported that pasture
type had a greater effect than breed on fatty acid composition, meat colour, stability
and vitamin E content. Lourenco et al. [2005] showed that feeding of forages from
semi-natural meadows resulted in better composition of milk fatty acids, compared to
forage from intensively managed grasslands.
Grazing as a tool to maintain biodiversity of grassland
326
It can be concluded that the type of sward grazed has a greater inuence on animal
performance and meat and milk quality than breed. Species-rich, diverse grasslands
allow for the production of high quality, health promoting animal products.
The examples cited above indicate that in most cases, extensive grazing is a useful
tool to maintain valuable grassland biocenoses and to preserve open landscapes. In
order to encourage farmers to continue these practices, extensive grazing must also
be technically and economically sustainable. In this context, the ndings of Isselstein
et al. [2007] who examined the effects of grazing intensity on animal production
and diverse conservation aspects are particularly promising. They concluded that
biodiversity-targeted extensive grazing systems have the potential to be integrated
into modern livestock production systems, as individual livestock performance was
comparable to that in a system using moderate grazing intensity.
Dillon et al. [2005] studied the feasibility of pasture-based milk production
systems in temperate regions. They indicated that such systems were characterized
by lower unit production costs, through lower feed and labour expenses, as well as
reduced capital investment. The systems utilizing grazed pasture are useful in regions
where the potential production of pasture is high, variation in seasonal pasture supply
and quality is low, and where large areas of land are available at relatively low cost.
Pasture-based systems allow for greater sustainability, increase product quality, improve
animal welfare and increase labour efciency. The production of green forage from
permanent grassland consumes less energy than crop cultivation, with relatively high
energy and protein yields. As a result, low-input pasture provides cheap green forage
[Soder et al. 2007]. Kasperczyk [2008] emphasizes, that economical rationalization
of pro-ecological use of meadows and pastures is possible only under sustained
management and should be supported by further, reliable scientic investigations.
It seems that extensive grazing can be a competitive agricultural practice in areas
less suitable for intensive agriculture. Frelich et al. [2008] surveyed the impact of
grazing on milk performance and health of dairy cows in sub-mountain areas and
found that health status of animals kept seasonally on pasture was signicantly better
as compared to that of cows fed with total mixed ration. They concluded that seasonal
pasture is benecial for milk production and ensures better welfare of grazed cattle.
Bugaud et al. [2001] and Collomb et al. [2002] also found dairy cattle pasturing in
unfavourable areas to be protable for milk production. They concluded that careful
planning and implementation of pasture systems allows for the reconciliation of
economic effectiveness with environmental goals, as was also shown by Lapointea
et al. [2000]. The latter authors presented an example from islands in south Quebec
(North America), where the introduction of rotational grazing allowed for the
simultaneous growth of duck populations and an increase of beef production, while
soil erosion was reduced.
Despite the possible economical advantages of extensive grazing systems, some
nancial support appears to be needed in order to support this kind of agricultural land
use. According to Mills et al. [2007], economic analysis has indicated that nancial
E. Metera et al.
327
support for farmers is essential to reconcile sustainable grazing systems with high
biodiversity. Isselstein et al. [2005] also raise the issue of compensation payments for
farmers to support grass production on high-biodiversity swards. Moreover, Nilsson
[2009] concludes that biodiversity restoration and conservation costs differ between
geographical areas. Therefore, nancial support must be suited to local conditions.
In any case, the benecial economic effects of low-input grazing systems would be a
strong argument in persuading farmers to maintain or restore this kind of activity.
The socio-economic aspect of animal use for biodiversity protection has been
investigated by several authors [Gandini and Villa 2003, Rook et al. 2004]. Duncan
[2005] also reviewed some papers dealing with the co-inuence of farm animals
and biodiversity. They concluded that agri-environmental schemes including the
use of grazing animals could be benecial for farmers, nature conservation and
communities. By re-establishing common property regimes, and providing carefully
designed economic and institutional incentives for a revival of transhumance, over-
grazing and under-grazing would be avoided on the local scale, and habitats would be
preserved for endemic ora and fauna. Warda and Rogalski [2004] suggest another
important benet of low-input, pasture-based animal production systems. They stress
the aesthetic and leisure importance of pastures, as well as of the animals grazing
on them. They also mention the social role of pasture management in maintaining
cultural heritage and restituting local animal breeds.
Many authors encourage the use of local breeds of cattle, horses, sheep and even
geese for low-input pasture management [Bartoszuk et al. 2001, Warda and Rogalski
2004, Groberek 2005]. The use of these breeds for landscape protection would
create a niche for threatened breeds and would support animal biodiversity. Another
aspect of the use of native breeds, besides the preservation or restoration of animal
genetic resources, is the production of region-specic products, labelled as Protected
Designation of Origin – PDO. The higher price of these goods would encourage
farmers to maintain a production system which is benecial for biodiversity and
environmental protection. In this context, Warda and Rogalski [2004] mention that
farmers specialized in animal production based on grassland are also seen as active
ecologists, protecting the environment and the natural landscape.
Conclusions
Animal grazing is essential for the growth of green biomass and composition
of plant communities on grasslands. Grazing creates favourable conditions for the
formation of habitat structure preferred by many endangered birds, small mammals
and invertebrates. As a result, grazing animals have a positive impact on biodiversity
of grasslands. As well as the benecial impact on biodiversity, extensive grazing
contributes to the aesthetic and leisure importance of pastures.
Inappropriate use of pasture – both overgrazing and undergrazing – poses a threat
for its biodiversity. Thus, both abandonment and overly intensive management of
Grazing as a tool to maintain biodiversity of grassland
328
pastured grassland are harmful for biodiversity and should be avoided. Light grazing
can be a tool to maintain or enhance biodiversity of grazed areas. The practice can also
contribute to the production of healthy food of high quality.
Animal grazing can be used as a tool to limit the expansion of weeds and shrubs
in open landscapes, but in most cases cannot stop or reverse natural succession.
Thus, for purposes of biodiversity conservation, grazing should be combined with
other practices, such as mowing, cutting or burning. The question of which method
or combination of methods is most suitable and most feasible in a particular area,
depends on local biological and socio-economic factors.
The conservation and protection of pastures and meadows requires the careful
selection of grazing management and appropriate number of grazing animals. Grazing
species differ in their preference of habitat and plant species, which can enable the
effective use of mixed grazing systems with different animal species.
The continuation of extensive pasture practices by farmers requires nancial aid
and greater social and political support, especially where large areas are concerned.
Research ndings suggest that existing agro-environment schemes based only on
blanket stocking rates are too crude to increase plant diversity and that site conditions
must also be taken into consideration. Moreover, the method of nancial support
must be suited to local conditions. Local authorities and farmers should co-operate to
obtain funds for appropriate agro-environment schemes. Government policies in this
area need to be continuously reviewed with respect to biological, environmental and
economic impacts. The design, implementation, monitoring and effects of agricultural
policies must be constantly evaluated and improved.
Strategic research is required into methods of achieving compliance with
environmental protection and sustainable agriculture legislation in grassland areas.
Therefore, there is a need for comprehensive research programmes combining ecology,
botany, agronomy, animal production and economics. The elds of interest include not
only interactions between grazing animals and biotic and abiotic elements of grazed
area, but also interrelationships with adjacent wild and agricultural biocenoses. This
touches on the subject of close cooperation between agricultural and conservation
experts. The research should include both eld experiments and development of
appropriate models, allowing for design of agro-environmental schemes aimed at the
protection of grassland biocecenoses.
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