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Towards reduced herbicide use in forest vegetation management



Mechanical, manual, thermal, biological and chemical methods of managing forest vegetation have, to a large extent, been developed independently. The effectiveness and relatively low cost of chemical herbicides, however, have led to systems of vegetation management that rely on their continued availability and the near exclusion of non-herbicide methods for controlling forest weeds. Greater public concern, perceptions of risk, and pressures exerted by some forest certification systems, have increased the need to provide a wider array of alternative methods that can reduce dependence on herbicides. In response, forest vegetation management research has widened to include investigations of alternatives to herbicides, along with initiatives aimed at reducing chemical use. An international review of progress indicates that reduced herbicide use may already be possible in many countries. There are however, a number of commercial, economic and social issues associated with the practical application of this knowledge, notwithstanding the fact that a more integrated approach is required to combine relevant methods of vegetation management, rather than attempting to practise alternative techniques in isolation from other silvicultural practices. This paper, together with appropriate examples, reviews pressures to reduce herbicide use as well as past and current research to develop alternatives to herbicides in eleven different countries, as well as identifying instances of the successful or unsuccessful implementation of this technology.
Southern African Forestry Journal – No. 207, July 2006 63
Review Paper
Towards reduced herbicide use in forest
vegetation management
K.M. Little
*, I. Willoughby
, R.G. Wagner
, P. Adams
, H. Frochot
J. Gava
, S. Gous
, R.A. Lautenschlager
, G. Örlander
, K.V.
and R.P. Wei
Institute for Commercial Forestry Research, PO Box 100281, Scottsville, South Africa, 3209
Forestry Commission Research Agency, Alice Holt Lodge, Farnham, Surrey GU10 4LH, United Kingdom
University of Maine, 5755 Nutting Hall, Orono, Maine, USA, 04469
Forestry Tasmania, 79 Melville Street, Hobart, Tasmania, 7000
Lerfob, UMR INRA-ENGREF, CR INRA de Nancy 54280 Champenoux, France
Cia.Suzano de Paper e Cellulose, Tavares, Km 169, Cx Postal 228, CEP 18.200-000, Itapetininga – SP
Forest Health and Protection, Forest Research, Private Bag 3020, Rotorua, New Zealand
Atlanta Canada Conservation Data Centre, PO Box 6416, Sackville, NB E4L 1G6
Växjö University, SE-351 95 VÄXJÖ, Sweden
Kerala Forest Research Institute, Peechi-680 653, Kerala, India
Sino-Forest Corporation, 3129-40, 31/F., Sun Hung Kai Centre, 30 Harbour Road, Wanchai, Hong Kong
* Corresponding author. E-mail:
Mechanical, manual, thermal, biological and chemical methods of managing forest vegetation have, to
a large extent, been developed independently. The effectiveness and relatively low cost of chemical
herbicides, however, have led to systems of vegetation management that rely on their continued
availability and the near exclusion of non-herbicide methods for controlling forest weeds. Greater public
concern, perceptions of risk, and pressures exerted by some forest certification systems, have increased
the need to provide a wider array of alternative methods that can reduce dependence on herbicides. In
response, forest vegetation management research has widened to include investigations of alternatives
to herbicides, along with initiatives aimed at reducing chemical use. An international review of progress
indicates that reduced herbicide use may already be possible in many countries. There are however, a
number of commercial, economic and social issues associated with the practical application of this
knowledge, notwithstanding the fact that a more integrated approach is required to combine relevant
methods of vegetation management, rather than attempting to practise alternative techniques in
isolation from other silvicultural practices. This paper, together with appropriate examples, reviews
pressures to reduce herbicide use as well as past and current research to develop alternatives to herbicides
in eleven different countries, as well as identifying instances of the successful or unsuccessful
implementation of this technology.
Keywords: Weed control, integrated forest vegetation management, herbicide alternatives, certification.
Forest vegetation management involves manipu-
lating vegetation and the associated micro-
environment to favour the survival and growth of
trees or other desirable vegetation (Comeau and
Spittlehouse, 1993). Successful vegetation manage-
ment strategies enhance productivity from an existing
or declining land base by increasing fibre yields,
reducing rotation times, and improving stem and
stand uniformity, whilst also improving wood and/or
pulping properties (Little et al., 2003a; Little et al.,
2003b; Wagner et al., 2006). On certain sites, without
suitable vegetation management, competition from
weed vegetation would reduce or eliminate forest
regeneration. To realise the potential productivity of
many forest sites, various vegetation control methods
have been developed, including manual, mechanical,
cultural, thermal, biological approaches, and the use
of herbicides.
Since their development in the 1940’s, synthetic
herbicides have been used extensively, and have
become fully integrated for managing natural
regeneration, plantations and forest ecosystems
world-wide. Their ability to control a wide range of
competitive plant species has meant that herbicides,
Southern African Forestry Journal – No. 207, July 2006
more than any other form of vegetation control, have
helped forestlands achieve their productive potential
(Wagner et al., 2006). Consistent and predictable
vegetation control has meant that the benefits from
other silvicultural practices, such as fertilisation
and genetic improvement could also be realised.
Globally there has been increased emphasis placed
on reducing pesticide residues in food, water and soil
(Navas, 1991; Wyse, 1992; Franklin et al., 1994).
Greater public concern, availability of data and
perceptions related to the use of natural resources,
have also led to increasing pressure to practice more
sustainable forest management.
The principles associated with sustainable forest
production are not new. Chapman (1931) described
sustained yield as the actual net yield of a productive
industry in which there is no permanent depletion of
the capital resource, which in forestry is represented
by the soil and growing stock. Sustainable production
is a fundamental objective in any business striving
for long-term survival, and as such, the continuity of
supply of forest products is central to the practice of
forestry (von Gadow and Bredenkamp, 1992).
However, the principles associated with “sustained
yield” are more far-reaching than conservation of the
productive capacity of the forest only. Interest in
monitoring the condition of natural resources has
grown world-wide and this is reflected in increased
community awareness and concern for the protection
of natural resources. The concept of sustainability
has been expanded to that of meeting the needs of the
current generation without compromising the ability
of the environment to meet the needs of future
generations (Norman, 1997). Many international
and national organisations and sectors within
communities have developed ecosystem or industry-
based indicators of resource condition. The Montreal
Process, International Standards Organisation (ISO-
14001), Forest Stewardship Council (FSC), Pan
European Forest Certification (PEFC) are examples
of systems providing a framework to describe, assess
and evaluate progress towards sustainable forest
management (Norman, 1997; Obser, 1998). Included
within many of the forest certification systems are
guidelines striving to reduce or eliminate herbicide
use. Together with increased social concern and
perceptions of risk, this has led forest managers to
question their dependence on herbicide technology
alone. Public demands for greater protection of forest
ecosystems, while at the same time demanding high-
quality timber products at low prices, present a
formidable dilemma to forest managers.
Over the past five decades, the effectiveness and
relatively low cost of herbicides have, in many
countries, led to management systems that are reliant
upon their continued availability. In these countries,
this trend has resulted in the almost near exclusion
of non-herbicidal methods of vegetation control. The
advent of herbicides provides a good example of how
scientific research, extension, industry and growers
can co-operate to propel new technology into the
mainstream of society (Wyse, 1992). However, since
the early 1990’s, in response to increased pressure
from the public and non-governmental groups, there
has been renewed interest from managers and
researchers into methods of reducing the reliance on
herbicides as the exclusive method for managing
forest vegetation. As a consequence, the scope of
forest vegetation management research in many
countries has been widened in recent years to include
alternatives to herbicides, along with initiatives
aimed at reducing present herbicide use. A few
countries in Europe have since the 1970’s had
restrictions concerning the use of herbicides in
forestry. For example, in Sweden this has led to the
development and use of non-chemical methods for
the successful establishment of conifer stands (Nilsson
and Örlander 1999). Although a number of papers
and conference proceedings highlighting these aspects
have been produced (Canadian Journal of Forest
Research, 23(10) 1993; Harrington and Parendes,
1993; McMcormack, 1994; Wagner, 1994; New
Zealand Journal of Forestry Science, 26(1/2) 1996;
Canadian Journal of Forest Research, 29(7) 1999;
Annals of Forest Science, 60(7) 2003), there has been
no review of the success of these initiatives, nor the
constraints with regard to their application. Progress
on the development of alternatives to herbicides
varies from country to country, and is dependent on
economic viability, regulatory processes, social
acceptance and ecological impact. For this reason,
eleven countries were assessed that exhibited
diversity in terms of: the types, ownership, and value
of their forests; where and when (if at all) pressure
came for a reduction in herbicide use; and any
actions or initiatives proposed and put in place for a
reduction in herbicide use, together with potential
reasons for their success or failure.
Australia has a significant forest industry based on
the multiple use management of both native forests
and plantations. The industry employs almost 80
000 people, has a $15 billion annual turnover and
makes a 1% contribution to GDP. Annual wood
production exceeds 24 million m
of log, with 40%
from native forests and the remainder from
plantations (ABARE, 2004) which now exceed 1.6
million ha or approximately 0.2% of the total land
Intensive management of plantations is carried out
to promote vigorous, healthy growth and to maximise
production per hectare. Standard practices during the
establishment phase include site cultivation,
vegetation control, and fertilisation, if required.
Effective vegetation management during this phase is
one of the major determinants of good early growth of
Southern African Forestry Journal – No. 207, July 2006 65
the tree crop under the majority of climate, site and
vegetation occurrence situations (Boomsma and
Hunter, 1990; Richardson, 1993). This is widely
recognised by many commercial plantation growers
in Australia and after more than three decades of
research has resulted in the development of successful
control methods based mainly on the use of herbicides.
The dominance of herbicide-based control methods is
due in large part to their effectiveness and ease of use
of in a wide variety of situations.
Historically, control of vegetation has changed
from manual, through mechanical to chemical control
by the 1970’s (Boomsma, 1982). In the 1960’s in South
Australia, chemical control of woody regrowth was
carried out with phenoxy herbicides (Boardman, 1988)
which enabled conversion of native forests and release
of newly established plantations from a wide range of
native and introduced woody species (Boomsma, 1982).
In the 1970’s glyphosate and hexazinone came into
prominence for control of grassy and woody vegetation
as plantations became increasingly established on ex-
pasture sites and second rotation plantations. Since
the mid-1970’s there has been intensive research and
development into all aspects of vegetation control with
the use of herbicides, including the testing of various
chemical combinations, formulations, application
techniques, new products, adjuvants and surfactants,
which provided forest managers with a wide range of
vegetation control options (Boomsma, 1982).
Since the early 1990’s there has been increased
environmental pressure and public scrutiny of forest
management and the use of herbicides, particularly
relating to catchment management and water quality.
The triazine group, particularly atrazine, has been
the major focus of attention with regards to off-site
movement and water quality. In some catchments
supplying drinking water to major towns and cities,
very strict controls have been enforced for the use of
herbicides during plantation management. This has
lead to serious reductions in survival and growth of
young trees. Research is being undertaken to quantify
the risk and find alternative herbicides that will not
move into water systems. There is an ongoing need,
therefore, to minimise the environmental impacts of
herbicides while making them more effective and
efficient, and appropriate to soil, site and species.
Many methods are being applied to improve the
efficiency of herbicide use, reduce the area treated
(spot or strip spraying), improve the application and
formulation technology, apply herbicides only to where
non-crop vegetation occurs, and improve vegetation
forecasting and timing of application.
In at least one case in Australia, a major plantation
grower has stopped using triazine herbicides during
establishment of eucalypt plantations and has been
actively seeking alternative approaches and more
integrated systems of management. This work has
included the evaluation of both pre- and post-plant
cultivation methods, manual slashing methods,
mulching and covercrops using oversowing techniques,
herbicide application techniques to reduce drift
(shrouded/shielded boomsprays) and hand application
equipment to improve herbicide application. Other
plantation growers are testing the efficacy of
alternative, non-triazine, residual herbicides. Biolo-
gical agents for the control of specific weeds such as
gorse and broom are also being investigated through
collaborative research between States and the
The implementation of non-herbicide alternatives
in industrial plantations has been low. Extra
cultivation methods that could be applied prior to
planting were limited to the amount of time available
prior to planting, terrain and soil conditions.
Cultivations carried out after planting are limited to
between the tree rows, have proved difficult, and in
some cases damaging to tree roots. Manual slashing
of vegetation can provide access for operations such
as pruning, and provides reasonable control on woody
vegetation, but is not satisfactory for herbaceous
species such as grasses that can rapidly regrow.
Multiple application of these mechanical methods
may be required which can become very uneconomic.
In the case of mulching, large amounts of material
are required, and it is very labour intensive and
therefore prohibitively expensive to apply. Covercrops
are difficult to establish and manage, and increase
management inputs. With grasses commonly being
a significant component of the covercrop, they can be
highly competitive to the tree crop, which means
herbicide control is required for each tree.
It is expected that further advances in vegetation
management, will require greater consideration of
the site quality, vegetation-tree interactions and the
processes or mechanisms involved (Wagner, 1993;
Cousens, 1996). An intensive study into competition
for soil water and nitrogen between a common grass
and young E. globulus (Adams, 2004) has improved
understanding of the timing, duration and intensity
of competition for these two important resources.
When applied to different site and resource levels,
this information allows managers to predict the
effects of competition on a site-specific basis and
target the management of vegetation more precisely.
Reforestation, with pines and particularly eucalypts,
has occurred over the last 100 years in Brazil. Besides
the commercial importance of these plantations,
reforestation and subsequent silvicultural practices
are seen as important vectors for the sustainable
development of Brazil as a country. Technical
innovations from the 1940’s, combined with greater
public input from 1970, and increased efforts by
private companies in the 1990’s has promoted Brazil
from a net importer to a net exporter of a whole range
of forest products.
Although reforestation was initially carried out
over significant areas by large private companies,
recently there has been a shift towards the planting
of smaller blocks by private individuals or companies.
Southern African Forestry Journal – No. 207, July 2006
Currently, 4.8 million ha are established to
plantations, creating direct employment for 0.5
million people, and 1.5 million people indirectly.
The intensified use of herbicides together with the
development of appropriate equipment and rates of
application from the 1980’s has also allowed for more
cost-effective and better control of competitive
vegetation in eucalypt stands than would otherwise
be possible using more traditional, intensive soil
preparation techniques (Silva et al., 1997; Toledo et
al., 1999). Few herbicides are currently available for
use during reforestation in Brazil, with strict
legislation limiting the registration of new products.
In addition, pressure for the reduction of herbicide
use from certification bodies as well as from the
public sector will mean that this is unlikely to
change. Currently, registered products do not give
the same degree of control, are non-selective, or
control groups of vegetation that are not competitive.
This condition, together with the high price of
available herbicides and environmental concerns,
has meant that forest owners are investigating
alternative methods for the management of vegetation
The development of alternative vegetation
management systems has not received much
attention, although herbicide use has been reduced
through integration with other silvicultural
practices. Any method that decreases the time to
forest canopy closure, or reduces the development of
competitive vegetation is seen as important and
includes appropriate harvest residue management,
fertilisation, and planting density (Gonçalves et al.,
2002). More densely stocked stands capture the site
resources quicker and reduce the duration of
vegetation control operations, whereas more widely
spaced trees together with the retention of some
vegetation in the inter-row has a positive effect on
nutrient conservation, reducing losses through
leaching when the root system of the trees are not
fully established (Gonçalves et al., 2004). Significant
advances in developing new methods for eucalypt
sprout control through the reduction of herbicide
spraying have recently been achieved by the
application of imazapyr through the trunk injection
technique, a more environmentally sound and
effective methodology than spraying the foilage.
Canadian forests have been critical to Canadian life
for more than ten thousand years. Their plants and
animals provided the First Nations (Indigenous
peoples of North America), and those that followed,
essentials for sustenance and comfort. Canadian
First Nation communities practised vegetation
management (using fire and transplants) to
encourage desirable plants and animals and
discourage others, millennia before the term was
coined. Most Canadian landscapes remain forested,
although humans and related management have
altered historical disturbance patterns. They are
10% of the world’s forests and 30% of its boreal
forests. Of the 417.6 million ha, 183.1 million ha are
non-commercial forest (largely wilderness), while
234.5 million ha are commercial forest. Of the
commercial forest, during the last decade, approxi-
mately 0.4% has been harvested annually (Natural
Resources Canada, 2004).
Although vast tracts of forest remain largely
untouched, forest harvesting has changed the
structure and composition of harvested areas
(Lautenschlager and Sullivan, 2002). Almost without
exception, conifer content (“softwoods”) in post-
harvested forests is decreased, often dramatically. In
addition, forested areas are decreasing close to human
populations, agricultural production centres, mill
sites, and major transportation routes.
Forest plantations (mostly of native spruce and
pine) are presently contributing fibre to Canadian
mills, with the bulk of forest harvesting, and much
regeneration, based on natural regeneration. During
the last decade approximately 435 000 ha, less than
half of the area harvested, were planted with conifers
in Canada annually. Although many provinces have
legislation requiring forest companies to regenerate
harvested areas to pre-harvest cover percentages,
many provinces also have restrictions that make it
difficult to successfully regenerate conifers. Herbicide
release (chemical removal of unwanted vegetation
allowing) accounted for approximately 83% of all
post-planting release during the last decade, but on
average it has only been applied to 154 000 ha
annually, 15% of the annual harvest area. Even
these treatments, however, seldom yield post-harvest/
post-treatment conifer stocking levels similar to pre-
harvest conditions.
The majority of herbicide use in Canada is in
agriculture; forest herbicide applications are a minor
use. Five active ingredients (glyphosate; triclopyr;
2,4-D; hexazinone; simazine) are used for forest
vegetation management. Glyphosate, however,
dominated overall useage on 94.7% of the treated area
from 1998-2001 (Canadian Council of Forest Ministers,
2002). Despite the established record of efficacy and
safety associated with forest herbicide use,
considerable research into effects of alternative
management approaches have been conducted in
Canada. Thompson and Pitt (2003) provide a recent
overview of vegetation management research and
practice in Canada. One of the most significant efforts
to examine alternatives to aerially-applied herbicides
was undertaken by the Vegetation Management
Alternatives Program (VMAP), funded by the Ontario
government, in the mid-1990s (Wagner, 1993).
VMAP investigated all seemingly appropriate
alternatives to herbicides (animal grazing, prescribed
fire, mechanical and manual methods, biological
control, and mulches), and field-tested these along
with standard herbicide applications (Wagner et al.,
1995). Environmental consequences of the most
promising alternatives were often determined during
pre- and post-treatment field-test monitoring. One
Southern African Forestry Journal – No. 207, July 2006 67
proposed approach, using domestic sheep to control
competing vegetation in forest plantations, was
considered but because of concerns about disease and
parasite transport to native wildlife, and possible
attraction or displacement of large carnivores, this
was rejected before major field trials were initiated.
A milestone accomplishment in Canadian forest
research directed at developing new alternatives to
herbicides has been the development of
Chondrostereum purpureum, a common forest fungal
pathogen, as a biological control agent for re-sprouting
woody plant species (Thompson and Pitt, 2003). This
pathogen has recently received government
registration for forest use as the product Myco-Tech
Paste™ (Myco-Forestis Corp.). It is the first
commercial biocontrol agent for forestry in North
America. Development and registration of this
biocontrol agent represents a major breakthrough,
particularly in the province of Quebec, where
herbicide use in forestry has been recently suspended.
One of the most significant comparisons of
ecological effects between herbicides (glyphosate and
triclopyr) and non-herbicide competition control
(cutting with “brush-saws” or a tractor with a “brush-
saw”-like attachment), was conducted by the VMAP
during the mid-1990s. That interdisciplinary
“Fallingsnow Ecosystem Project” (Lautenschlager
et al., 1998) was a large-scale replicated block study
that examined responses by most major abiotic and
biotic environmental components. The authors
reported few short- or long-term differences, except
in cost, among the alternatives tested and concluded
that conifer release, regardless of the method used,
is relatively inconsequential for most environmental
components found in regenerating northern forests.
Post-harvest disturbances like conifer release are
minor compared with harvesting, but following
harvesting, planting, and conifer release plant and
animal species richness and diversity are commonly
as high as they will ever become in northern forests
(Lautenschlager and Sullivan, 2002). Still, public
perceptions about environmental and human health
risks associated with herbicide treatments are real.
Forest managers employing herbicides must
recognise that opposition to herbicide use in forestry
is high and increasing (Wagner et al., 1998), despite
accumulated scientific documentation of their safety
and relatively benign environmental effects. So, in
addition to supporting additional scientific
documentation of consequences of alternative
treatments, managers must understand that in the
future social input will be increasingly common if
not required (Lautenschlager et al., 1998).
Although broadcast conifer release treatments
are still the norm in Canada, one new development
has been the movement, at least in some western
forests, to the increased use of both ground- and
helicopter-applied “patch” release treatments. To
some degree this has been necessitated by the
significant biomass of non-conifer vegetation left on
site (often required by legislation) during harvesting.
Root sprouts from that residual, however, often
produce significant competitive biomass in and
around the residual areas. Because patch treatments
are new, it is unclear whether they will contribute to
survival and improved growth of the planted conifers.
Clearly micro-site quality is highly variable and
patch treatments focus on the most productive micro-
sites. For a variety of reasons site resources may be
equally or more limiting in areas where less
competitive biomass has developed.
Studies of alternative treatments commonly fail
to examine both the economic and ecological
consequences of the full range of alternatives,
including standard herbicide treatments. Therefore,
future examinations of alternatives should ensure
that economic and ecological consequences are
examined in detail. It is not clear that any alternative
will be more efficient, effective, or less environ-
mentally damaging than the herbicides presently
being used in Canada. However, it is clear that the
conifer component in post-harvested forest
ecosystems in Canada has been reduced, and although
herbicides may not be the only way to reverse that
trend, at this time herbicides provide the best hope
of restoring ecosystems changed dramatically by a
century of forest harvesting.
Herbicide use in forestry in Canada has decreased
slightly during the last decade, and efforts focused on
understanding effects of herbicides and alternatives
have also decreased, but some research concentrating
on understanding longer-term consequences of older
treatments continues. One key finding to emerge over
the last decade is the importance of early treatment if
the intention is to ensure conifer survival and maximise
growth. Evidence supporting this need, including the
advantage of pre-planting herbicide site-preparation,
continues to mount, while a variety of publics continue
to be concerned about the use of any herbicides for
forest vegetation management.
Although additional research in certain areas
may be necessary, at this time a national effort to
inform the public of the need for site-preparation,
timely planting, and release would benefit Canadian
forests and the Canadian economy in the long-run.
Additional research refining what is already known
will not convince a sceptical public of the value of
herbicides for managing these forests. If governments
hope to continue to benefit from forest production in
Canada, serious public education (not a propaganda
campaign), based on research that has already been
conducted, is the most desperate need.
Although deforestation has probably been the main
interaction between humans and forests, silvicultural
activities such as tree planting and tending have been
documented for more than two thousand years
(ECGPH, 1998). In response to an increase in natural
disasters such as floods and droughts, together with
wood shortages arising from the rapid decline in forest
Southern African Forestry Journal – No. 207, July 2006
resources and worsening ecosystems, extensive
government funded reforestation programs were
initiated within the last century (ECGPH, 1998). This
has resulted in the establishment of 46.7 million ha of
plantations and accounts for 29.4% of the forests in
China (26% of the world’s plantations). As these areas
were planted mainly for reforestation purposes, they
received low-level investment and management.
Subsequent to the availability of World Bank loans
from the early 1990’s, fast-growing trees have been
planted and intensively managed on a commercial
basis for the production of forest products (CSFA,
2003). Increased involvement from the private sector
from 1996, has also contributed to the establishment
of commercially managed plantations, which currently
account for 3.7% (1.7 million ha) of the total area of
plantations in the country (CSFA, 2003).
Throughout the history of forestry in China, the
management of competitive vegetation has always
been regarded as one of the most important of the
silvicultural practices. Regardless of the end-use,
the vegetation has been controlled as a form of site
preparation prior to planting, as well as for releasing
the tree from competition during establishment.
Current vegetation control methods include manual,
mechanical, burning, chemical, intercropping as
well as various combinations of the above. The most
common method used in plantations established for
wood production is burning prior to planting followed
by manual clearing.
Chemical control of vegetation was first considered
in 1959, subsequently resulting in extensive research
into herbicide use throughout the country (Wang et al.,
2001). Much of this research was aimed at screening
herbicides for application in forest nurseries, young
plantations (Feng, 2001; Xu et al., 2003), high-value
tree crops (He et al., 2000) and forest fire-breaks (Lu et
al., 1999; Zhang, 2003). This research had a positive
contribution on the management of forest vegetation
control (Wang et al., 2001). Among the many herbicides
available, only a few are recommended on a regular
basis. These include oxyfluorfen and haloxyfop-r-methyl
for use in forest nurseries, and glyphosate, hexazinone
and 2,4-D butylate for reducing competition in young
stands, or for the maintenance of forest fire-breaks
(Wang et al., 2001). The use of herbicides as an
alternative to other forms of vegetation control is now
well established, particularly in: forest nurseries;
economically well-developed regions such as the coastal
areas in the south and east of China; management of
high-value species such as teak, ginkgo and selected
woody herbs; plantations owned by well-established
forest farms (He et al., 2000); and for establishment of
forest fire-breaks (Lu et al., 1999).
Despite the successful use of herbicides for the
management of vegetation in the situations
mentioned above, they are not commonly used in
reforestation programs even for the establishment of
commercial eucalypt, poplar and pine plantations,
most of which were planted in the last decade and
involve intensive management. Reasons for this are
firstly, most of these plantations are located in the
poorer, rural regions of China where field operations
are carried out by low-paid, unskilled labourers from
local communities. Despite the gradual increase in
labour costs over time, and reduced costs associated
with manually applied herbicides, the small
differences between manual and chemical vegetation
control costs does not warrant a switch (Lu et al.,
1999; He et al., 2000; Wang et al., 2001). Secondly,
for the effective control of competing vegetation with
herbicides, a degree of skill and knowledge is required.
As most operations are carried out by seasonal and
unskilled labourers, frequent training would be
necessary if herbicide use were to be considered.
Thirdly, most of these plantations have been
established on long-disturbed, ex-agricultural fields
where any vegetation present is easily controlled by
burning followed by manual hoeing. Fourthly,
ecological, environmental and social concerns related
to herbicide use are also taken into account by the
majority of commercial plantations owners (Wei,
2003). This is particularly true for those plantations
established in the last decade by private companies,
or with funds obtained from the World Bank, which
required the inclusion of the above issues into their
management (Bai, 1993).
The potential exists for the increased use of
herbicides in fast-growing plantations that are aimed
at maximising production. However, existing control
measures are currently regarded as successful and
until such a time as the use of herbicides become
more cost-effective, it is unlikely that their use will
increase. On the other hand, the concept of integrated
forest vegetation management through which
herbicide use is reduced, and site productivity is
continuously maintained or improved, is nowadays
well accepted among plantation scientists, owners
and managers (CSFA, 2003; Wei, 2003). These
principles are actively practised by certain companies
or sectors (Wei, 2003) where different operations are
integrated, and included various combinations of
burning, mechanical or manual clearing of the site
prior to planting, manipulation of planting time,
density and spacing to allow for the shortest time for
the stand to capture the site, manual weeding or
chemical weed control at reduced rates, and the
inter-planting “green manures” or cash crops to
reduce or suppress unwanted vegetation. To be able
to expand these practices to be all encompassing, a
range of relevant issues need to researched and
developed, including the development of long-term
management plans, plantation type, land use history,
site accessibility and topography, investment budget,
feasibility of alternative vegetation management
practices, cost, and ecological, social or environmental
Southern African Forestry Journal – No. 207, July 2006 69
Commercial forests, occupying an area of 14 million
ha, cover a quarter of the metropolitan territory in
France (Cazettes et al., 2002; IFN, 2003). The
majority of these forests consist of naturally
regenerated native forest species, such as pines, fir,
spruce, oak, beech and various broadleaves species,
with only 5% established to exotic trees (Douglas fir,
red oak and several poplar clones). The growing
stock is estimated at 2 000 million m
, with 60%
broadleaved species and 40% conifers.
The metropolitan forests consist of high forests
(54%), a mixture of high forests and coppice (31%), or
coppice alone (IFN, 2003). The high forest is mainly
mono-specific and is dominated by oaks (Quercus
petraea and Q. robur), by conifers such as maritime
pine (Pinus pinaster), common silver fir (Abies alba),
Norway spruce (Picea abies) and Scots pine (Pinus
sylvestris). The mixtures of high forests and coppice
are multi-specific, multi-storied and widely dominated
by broadleaves species such as beech (Fagus
sylvatica), Spanish chestnut (Castanea sativa),
common ash (Fraxinus excelsior) and others.
France is an industrialised nation with a population
that is predominantly urban. Increased public pressure
regarding ecologically sound management practices
and free access, have sometimes resulted in formal
charter agreements between owners and individuals
or territorial groups (Bessière et al., 2002).
Traditionally French forests fulfil multiple uses: wood
production; social function; protection of biodiversity;
and natural resources, although only wood production
and to a lesser extent hunting, provide sources of
income. Many of the forests are either currently
certified with PEFC (amongst others) or are committed
to certification in the near future (Colinot, 2003).
Some of these forests are also bound by charters,
which place an even higher emphasis on the
conservation of the environment (Natura 2000
network). Current management trends include mainly
those silvicultural practices that will enhance the
diversification of commercial species through assisted
natural regeneration. These practices arose from the
need to re-establish close to 450 000 ha of damaged
forests following catastrophic storm damage in 1999
(Wincèlius, 2002), about 6 or 7 times the annually
regenerated areas.
From the 1970’s, herbicides have been used to
enhance natural or artificial regeneration, and to a
far lesser extent to optimise yield in intensively
managed forests. Herbicide use varies with the
intensity of management, the degree of control
required, and the receptivity of forest manager
(Frochot et al., 2002a), and herbicides are rarely
used more than one or two times during a rotation,
if at all. The forest area treated annually is less than
0.35% and forest managers are encouraged to respect
any environmental constraints when using herbicides
(Gama et al., 1987; Barthod, 1994; Wehrlen et al.,
1994; Barthod and Landmann, 2002). Although there
has been a marginal increase in herbicide use in
intensively managed areas (as in maritime pine),
there has been a corresponding decrease in most
other areas. This decrease can be attributed to the
attitudes of forest managers regarding herbicide
use, ecological concerns, and restrictions placed on
the use of specific herbicides.
From 1995 there has been a further decline in the
number of herbicides used in French forests (Gama,
2002) due to a combination of recommendations from
government organisations to use only herbicides
specifically authorised for forestry, the EEC which
limits pesticide use (such as triazines, fosamine
ammonium, dalapon), the time taken to register
forest herbicides that are not seen as a priority due
to minor usage, and the lack of commitment from
pesticides companies to invest in the registration of
new herbicides with limited forest use.
Initiatives to reduce herbicide use are at present
varied and include the testing of replacement
herbicides that control only specific vegetation types
rather than eradicating all vegetation (Gama, 2002;
Frochot et al., 2002a), through the combination of its
usage with other forms of vegetation management
(manual and mechanical), and by reducing the area
that needs to be treated to that immediately
surrounding the seedlings (Frochot et al., 2002a).
The utilisation of high-quality seedlings (size, quality,
mycorhization) is practised in low-density
plantations. Research into alternative practices is
focused mainly on the replacement of competition,
and consists in modifying the composition of existing
vegetation (Frochot et al., 2002a), or in sowing a
fixed mixture of herbaceous species (Frochot et al.,
2002b). The first method is well accepted in forests,
but the second will need further research before it
can be practically and commercially viable.
Plantations are an important source of pulpwood and
fuel in India. Although teak (Tectona grandis), which
is native to India, was planted from 1842, the large
scale planting of eucalypts and acacias (both exotics)
commenced from the 1960’s. This expansion of area
under plantations has been driven by increased local
demand for wood and other products, and by
community pressure to diminish dependence on native
forests. The total area under plantations is
approximately 32.5 million ha (Brown and Durst,
2003). Of this, teak, which is used mainly as a source
of timber, occupies an area of 1 million ha, and
eucalypts which are used as a source of pulpwood,
around 4.6 million ha. Plantations were initially
planted into indigenous grasslands, or in areas cleared
of natural forests, the latter of which was halted by
the Government of India in 1982. Thereafter, new
plantations could only be re-established after
harvesting existing plantations.
Most of the natural forests and plantations are
owned by the government, with the majority of the
Southern African Forestry Journal – No. 207, July 2006
plantations grown for timber or pulp. Productivity of
these plantations is considerably lower when
compared to world standards (Sankaran, 1999).
Competing vegetation has been identified as a major
factor contributing to this low productivity, with an
increase in Eucalyptus tereticornis performance of
up to 138% possible through regular vegetation
control in plantations in Kerala (Sankaran, 2004 –
unpublished data). The major competitive species in
teak and eucalypt plantations are broadleaves and
include Chromolaena odorata, Lantana camara,
Mikania micrantha, Mimosa invisa and Ageratum
Various control measures including mechanical,
cultural, chemical and biological have been researched
and recommended for the control of unwanted
vegetation (Singh, 2001), unfortunately none has
resulted in any substantial impact on either their
distribution or abundance. The first use of herbicides
dates back to 1937, with 2,4-D introduced in 1948.
Since then a large number of herbicides have been
used on an experimental scale in plantations, and
include glyphosate, paraquat, diuron and oxyflurofen
(Choudhury, 1972; Nair, 1973; Sankaran et al.,
2002). Despite this, herbicides are seldom used on a
regular basis for the management of vegetation due
to concerns related to their toxicity, the high cost of
the products, and the availability of cheap labour for
manual control.
Revenue earned by the government from the
plantations is negligible since products such as acacia
and eucalypt pulpwood is supplied to the industries
at a highly subsidised rate. This has compelled the
government to treat plantation management as low
priority. The decline in productivity over successive
rotations due to sub-optimal management has meant
that plantations in some states, for example Kerala,
are no longer able to provide the required quantity of
raw materials to the affected industries. Despite the
urgent need to increase productivity, attempts to use
herbicides to help achieve this have met with strong
resistance from the public due to perceived ecological
and environmental concerns. A similar situation
occurs in the smaller plantations under private
ownership where manual control of vegetation is
preferred over herbicides.
Plantation production of tea and coffee in north-
east India is highly dependent on herbicides (Barbora,
2001) and attempts to use alternative cultural weed
control in this and other agricultural sectors involving
local communities have so far proved to be
unsuccessful (Murphy, 2001). If similar methods
were to be applied in forest plantations, it is doubtful
they would be successful. Manual weeding is also not
a viable option in plantations due to the rapid
regeneration of the vegetation, combined with the
high costs involved. The control of specific species
using biological control are preferred over other
methods by all concerned. Costs are relatively small,
risks minimal and potential benefits considerable.
Although a number of biocontrol agents have been
introduced into India, mainly for the control of
Chromolaena, Lantana and Parthenium (Singh,
2001), these attempts have been largely unsuccessful,
or at best successful only at a local level (Evans,
2001). Reasons for recurrent failures are linked to
the genetic diversity of the species, their ability to
adapt to a range of ecosystems compared to the
biocontrol agents, lack of expertise in handling
biocontrol agents, absence of co-ordinated follow-up
actions after the introduction of the agents, and a
lack of information on the ecology and distribution of
the weeds. Little effort has been made to examine the
possibilities for exploiting indigenous or exotic host-
specific pathogens, even though recent studies in the
neotropics have indicated that for the latter, the
potential exists.
Integrated vegetation management programmes
involving mechanical, cultural and chemical methods
in conjunction with biocontrol agents have been
proposed and discussed on several occasions within
the country, but to date, concerted attempts have not
been made to implement any of these, and reasons for
this are unclear. Yet another suggestion is the
adoption of an effective natural resource management
strategy to enhance biodiversity in the landscape
and thus keep the biological invasion, including
unwanted vegetation, under check (Ramakrishnan,
2001). This suggestion again needs testing in the
field which may take several years for any observable
To summarise, the management of vegetation
using herbicides in forest areas has not been an
option in India so far, a situation that is likely to
persist for some years to come. To avoid any future
misconceptions regarding herbicide use, efficient,
environmentally safe and sustainable methods need
urgent development. To achieve this, international
co-operation is needed by way of information sharing,
technology transfer and capacity building.
New Zealand
New Zealand is a resource-based, industrial nation
with a total land area of 27.1 million ha and a
population of 4 million. Plantation forests, utilising
exotic tree species (mainly Pinus radiata), cover 1.8
million ha (7% of the total land area) and contribute
4% (NZ$ 3 546 million) to the GDP (New Zealand
Forest Owners Association, 2004). The importance of
managing competitive vegetation in New Zealand
plantations has long been recognised. Herbicides are
the most widely used tool to control competing
vegetation, although non-chemical methods are
increasing in importance (Richardson, 1993). Ray
and Richardson (1995) stated that, “without good
weed control it is doubtful whether commercial
plantation forestry would be economically viable on
many sites”. Herbicides have long been the principlal
method for controlling unwanted vegetation, initially
with the use of agriculturally derived chemicals in
the 1960’s. Over the last 40 years many changes
Southern African Forestry Journal – No. 207, July 2006 71
have occurred. Prior to 1970, herbicides were rarely
utilised for site preparation, with manual and
mechanical vegetation control methods in conjunction
with prescribed burning being the preferred approach.
During the 1970’s, there was a shift towards the use
of herbicides applied as a pre-plant spray followed by
a prescribed burn. These herbicides (mainly the
phenoxy type herbicides) with relatively high eco-
toxicity were applied using fixed wing aircraft at
high spray volumes (200 – 350 l ha
). Diesel was
frequently used to enhance herbicide performance.
Since the mid-1980’s there has been a concerted
effort from within the forest industry to reduce the
use of herbicides, initially driven by the need to
reduce costs associated with the management of
vegetation, and more recently by public concern
regarding toxicity and requirements from forest
certification bodies.
Herbicide use and rates of application have been
reduced by a combination of the following; new
herbicides replacing some of the more toxic products
used in the past; the spraying of herbicides becoming
more affordable with helicopters, allowing also for
directed application; herbicides applied at lower rates
with improved efficacy by the addition of adjuvants;
improved application techniques; and reducing the
area that needs to be treated (spot release) as an
alternative to a complete cover spray (Richardson et
al., 1997a). Currently 26 herbicides, or herbicide
mixtures are registered for use in New Zealand
forestry. These herbicides are generally classified in
the least hazardous “non-scheduled” category based
on oral and dermal toxicity. Research has shown
that environmental impacts from using herbicides
in New Zealand are often lower than from alternative
options such as crushing and burning. In addition
the chemical control of competitive vegetation is
more cost-effective than manual operations, or with
the use of cover-crops alone (Richardson, 1993).
In the 1990’s New Zealand Forest Research
developed two software decision support systems,
Vegetation Manager (VMAN) and Spray Safe Manager
(SSM) in collaboration with the U.S.D.A. Forest
Service (Richardson et al., 1997b). VMAN is a decision
support system that assists the user in selecting
which vegetation management treatment should be
used to optimise vegetation control operations. SSM
calculates aerial spray deposition, drift and either
vegetation control efficacy or damage to non-target
plants. Both systems help reduce the quantity, as
well as area over which herbicides are applied.
The New Zealand “principles for commercial
plantation forest management” states that
environmental excellence in plantation forest
management is the primary objective (New Zealand
Forest Owners Association, 2004). Over the past 20
years the forest industry has significantly improved
all facets of vegetation management practices
including reducing herbicide rates, using products
with lower toxicity and less use of practices that
degrade site quality.
South Africa
Timber is a scarce resource in South Africa (SA)
where the area under natural forests is limited (<
0.5%). To address this, timber plantations were
established, from the late 1800’s onwards, on
previously un-afforested land using exotic tree species
(pines, eucalypts and Acacia mearnsii) (von Gadow
and Bredenkamp, 1992). The total area of plantations
is approximately 1.1% of the area of South Africa, yet
they contribute 9% to the gross value of agricultural
output in SA. Although most of the timber produced
is used as a source of sawlogs, pulpwood and mining
timber (94.5%), 5.5% is used for other purposes
including poles for building, and wood for fires and
charcoal. This is important in a developing country
where most of the population live in rural areas and
do not have access to any other form of building
material and energy. Of the 1.4 million ha planted,
75 000 ha are re-established annually (Forestry
Economic Services, 2002). Silvicultural practices
during re-establishment are designed to take full
advantage of the sites’ productive potential, and as a
result, intensive operations, including land
preparation techniques, appropriate spacing,
fertilisation and vegetation management are practised
widely during re-establishment.
Most of the plantations are privately owned (76%)
with the emphasis on maximising productivity on a
sustainable basis. Until the late 1980’s, herbicides
were not used extensively in SA forestry, with most
vegetation management operations carried out by
hand or with hand-held implements. Around this
period early competition trials demonstrated potential
yield benefits, and this together with the availability
of glyphosate, provided the forester with the means
of significantly improving yield, at a reduced cost,
and on a consistent and predictable basis. Although
there was a shift towards the use of herbicides, this
was not to the total exclusion of manual weeding, nor
did it become less labour intensive, with all herbicides
applied by hand either as a broadcast application or
a directed spray. Since the majority of the forest
owners in SA subscribe to the principles of sustainable
management, 80.5% of the total area afforested is
currently certified with FSC, ISO 14001, or both. As
these forest owners provide funding for most of their
silvicultural needs through private research
organisations, any recommendations made must
take into account the concepts of the relevant
certification bodies. This has seen the development of
research initiatives aimed at refining current
vegetation management standards without compro-
mising productivity. Work includes trials demon-
strating the viability for reducing areas around the
trees that need weeding as well as the frequency of
weeding operations, the target control of specific
vegetation types, the development of standards for
cover-cropping, the adjustment of weed control
standards according to site (on a regional level),
immediate and historical land use, methods of site
Southern African Forestry Journal – No. 207, July 2006
preparation and species to be planted (Little and
Schumann, 1996; Little and Rolando, 2001; Jarvel
and Pallett, 2002; Little et al., 2002; Little and
Rolando, 2004). All recommendations rely on the
integrated management of vegetation, incorporating
both a reduction in herbicide use, together with non-
herbicidal forms of vegetation control.
Although these results can be considered successful
from a research perspective, in that they provided
solutions to the questions asked, few have been
applied commercially (Little and Dyer, 2002). This
has raised concerns, especially in identifying issues
that prevent the implementation of vegetation
management recommendations, and include,
robustness of research findings, transfer of
technology, complexity of weed growth information,
institutionalisation of systems and economic and
political constraints (Little and Dyer, 2002). Key
elements that can constrain the successful transfer
of technology in SA forestry include: a resistance to
change (including the so-called “not invented here”
syndrome); an inability to consume the technology
(company structures are inflexible); an inability to
understand and therefore use the technology (too
complicated); inappropriate technology (not practical);
unrealistic expectations as to what can be obtained
from research; the changes proposed through the
application of technology do not impact the way the
manager is measured; and the fact that the economic
return for the company is not perceived to be worth
the additional resources to implement the
recommendations (Little and Dyer, 2002).
About 60% (ca 23 million ha) of the land area in
Sweden is covered with forest, and consists of a
mixture of naturally regenerated and planted forests.
About 85% of the standing volume is Norway spruce
or Scots pine. Other important species are birch
(Betula sp.), oak (Quercus robur), and beech (Fagus
sylvatica). Most forests are a mixture of species, with
composition varying from north to south relative to
the many climatic zones, and as such monocultures
are uncommon. Current forest policy is against the
introduction of exotics and as such the only exotic
species of any importance is lodgepole pine (Pinus
contorta) that has been planted on approximately
2% of the area.
Sweden is a highly developed, industrial nation,
and although highly mechanised, the forest sector
provides direct employment for about 100 000 people.
Prior to 1975, large areas were treated with herbicides,
although environmental concerns around this period
led to the government placing restriction on future
herbicide use. Approximately 14 million ha of forests
are certified with either FSC or PEFC. The public
have access to all forests, and since 1993 forest policy
places equal emphasis on the environment and wood
production. Management of the forests for multiple-
use is therefore standard.
Vegetation occurring within forests is managed
on two occasions, prior to planting, and in young
stands when unwanted (mostly broadleaved) species
are removed. No herbicides are used for the re-
establishment of forests, with only limited herbicides
used when planting into ex-agricultural fields. Prior
to planting, the soil is scarified, providing effective
control of vegetation, similar to that provided by
herbicides on many sites (Nilsson and Örlander,
1999). About 70% of the areas regenerated in Sweden
are mechanically scarified before planting (Swedish
National Board of Forestry, 2003). Disc trenching,
patch scarification or mounding are the most common
method of scarification, although inverting might
allow for improved seedling establishment where
vegetation is particularly competitive (Örlander et
al., 1998; Hallsby and Örlander, 2004). Damage to
seedlings after planting by the pine weevil (Hylobius
abietis) is the most serious problem affecting
successful re-establishment. As a strong correlation
has been found between vegetation in scarified areas
and risk for damage (Örlander and Nordlander,
2003), the duration of vegetation control after
scarification is important. Planting as soon after
felling as possible, preferably within the same year,
reduces the negative impact any vegetation may
have on the seedlings (Nilsson and Örlander, 1999).
Other methods to reduce the impact of vegetation on
tree growth include, the selection of species less
sensitive to competition (such as Norway spruce),
and the planting of Norway spruce at a higher
density resulting in more rapid canopy closure.
Competition, especially from some broadleaved
species may have a negative impact on the production
of target species (usually Norway spruce or Scots
pine). Although these broadleaved species add to
species diversification and fill gaps in the canopy,
most of them are removed using pre-commercial
thinning that sometimes is costly. Pre-commercial
thinning is made on 200 000 – 300 000 ha of Swedish
forest annually (Swedish National Board of Forestry,
2003). During the last 10 years this pre-commercial
thinning has not been carried out according to need
and this has the potential to impair future economy.
In conclusion, competition from unwanted
vegetation following planting might be a problem,
but planting as soon as possible after scarification at
a high density can reduce any negative impact.
Currently, there is no need for removing broadleaves
with herbicides after re-establishment, provided pre-
commercial thinning is carried out correctly.
United Kingdom
Woodlands occupy 2.7 million ha, or 11.6% of the
land area of the United Kingdom (UK). No virgin
natural forests remain. Less than 1% of the land
area is occupied by ‘ancient semi-natural’ woodlands,
which are defined as sites which have been
continuously wooded since 1600 AD, and although
managed, still comprise predominantly native trees
Southern African Forestry Journal – No. 207, July 2006 73
that have not been planted. Of the remaining forest
area, 58% consists of mainly introduced exotic
coniferous species such as Picea sitchensis, Picea
abies, Pseudotsuga menziesii, Pinus spp., and Larix
spp. grown as plantations, and the balance native
broadleaves. Around 40% of woodlands are publicly
owned, and approximately 25 000 ha are planted or
restocked annually (Forestry Commission, 2003).
The UK has an industrialised economy and a
largely urban based population. Since the 1920’s
successive governments have encouraged land owners
to create new woodlands, and to maximise the
productivity of existing forests through the scientific
application of intensive techniques such as
coniferisation, fertilisation, cultivation, improved
planting stock and the use of pesticides. However,
since the 1970’s there has been a shift in emphasis
away from establishing a strategic reserve of timber
towards providing multiple use woodlands. This
trend has been accelerated in recent years with the
real terms reduction in timber prices, such that non
market, intangible benefits have become increasingly
important. Most woodland management in the UK
now includes one or more of the following major
aims: to promote and conserve biological diversity; to
improve the landscape; to provide a recreational
resource; and to produce timber and hence encourage
rural development.
The pressure to maximise production from a site
to the exclusion of all other objectives has therefore
reduced. One result of this shift in the objective for
woodland management has been a reduction in the
amount of money owners are prepared to invest in
operations such as vegetation management. The use
of herbicides is easily the most cost effective method
of weed control in the UK, but even so, economic
pressures have encouraged mangers to limit spraying
only to areas where it is necessary to allow
establishment of trees. Economic pressures and
changing objective have therefore led to some reduction
in herbicide use in UK forestry.
In addition, UK Government and European Union
policy is to minimise pesticide use as far as possible.
Statutory codes of practice (HSC, 1995) oblige
managers to consider whether, in any given situation,
pesticide use is really necessary and if possible to
adopt either wholly non chemical methods, or
techniques based on reduced quantities of chemicals
used as part of an integrated approach to crop
management. The European Union Plant Protection
Products Directive is intended to harmonise member
states regulation of pesticide use. One consequence of
this legislation is a review of all European registered
pesticides to a common data standard (Whitehead,
2004). Those active ingredients with adverse impacts
on the environment or operators, along with older,
often generic, less profitable activities where
additional data generation is not economic, will have
their approvals revoked. This has led to a reduction
in the number of pesticides that are available to be
used in forests, and has further encouraged managers
to consider alternative chemical and non chemical
solutions to their vegetation management problems.
A voluntary certification initiative the United
Kingdom Woodland Assurance Standard (UKWAS,
2000), which is approved by both the FSC and PEFC,
gives standards for sustainable forest management
against which management units can be assessed.
The standard calls for managers to develop a strategy
which will lead to a reduction, and eventually
elimination, of synthetic pesticide use. Where there
is no practical alternative not entailing excessive
cost, the use of synthetic pesticides is still permitted.
Economic pressures have probably had the greatest
effect to date in reducing the amount of pesticides
used in UK woodlands. By comparison, so far
legislation and other initiatives such as UKWAS
have probably only had a limited impact on levels of
usage. This may again be due to economics. For the
majority of pest and weed problems in UK forestry a
non chemical method of management already exists,
but in most cases the alternative is at least a factor
of ten to a hundred times more expensive than using
However, the reduction in available products, and
the adoption of certification initiatives will result in
managers being faced with increasing pressure to
reduce pesticide usage in the future, whilst there is
little immediate likelihood of more resources becoming
available to fund this change in practices. Alternative
silvicultural approaches to the management of
woodlands such as continuous cover forestry (Mason
et al., 1999) and restoration of conifer plantations on
ancient woodland sites to native species (Thompson
et al., 2003) partly reflect changing objectives for
woodland management, but there is also the perception
amongst some mangers that these silvicultural
systems will offer a lower cost approach that may
require less intensive inputs. However, in reality
such approaches may still require the use of herbicides
in the transformation phase, so an immediate
reduction in inputs may not be possible.
For more conventional felling and replanting
systems, complete replacement of non chemical
options may be far less practical than using a
combination of techniques to reduce chemical use.
This may be one area where research in the UK
needs to focus, rather than striving for an elusive
direct replacement for cheap, effective chemical
regimes. However, some pressure groups might see
such an approach as a dilution of their eventual aim
of eliminating all synthetic chemical use in
woodlands, and managers with limited time may be
reluctant to replace a relatively straightforward
chemical regime with a more complex system
involving a combination of techniques.
Research into alternatives to pesticide use has
taken place over many years in the UK (Willoughby,
1999), but one barrier to the adoption of an integrated
approach may have been that information relating to
individual pest, disease, vegetation and wildlife
problems has often been published separately. New
Southern African Forestry Journal – No. 207, July 2006
guidance (Willoughby et al., 2004) aims to start to
address this by providing a decision framework to
allow managers to take an integrated approach to
reducing chemical use when dealing with these
damaging agents, and to determine the method of
management that will be likely to have the least
impact on the environment. Before widespread
adoption of an integrated approach to vegetation
management in the UK takes place, it is likely that
more research and technology transfer will be
required on the fundamental need to weed under
different silvicultural regimes and locations, as well
as investigations into novel lower cost, low impact,
socially acceptable techniques for pesticide reduction.
United States of America
About 33% of the land area in the United States of
America (US), or 302 million ha, is covered by forest
(Smith et al., 2001). The forest area is divided nearly
evenly east and west of the central plains. The
forests are diverse, containing over 800 species of
trees, 82 of which are exotic. About a third of the
forest was cleared for agriculture during the 19
century by European settlers. Of the total forest
area, about 204 million ha (67%) is classed as
timberland capable of producing more than 1.4 m
and not legally restricted from timber
About 42% of U.S. forestland is publicly owned,
either by individual states or the federal government
(Smith et al., 2001). Public forestlands predominate
in the western states and privately owned forests
dominate in eastern states. About 21 million ha (7%)
of all U.S. forestland is reserved from commercial
timber harvest in wilderness, parks, and other legal
reserve classifications. The total area of timberland
has remained relatively stable during the last half of
the 20
century, with a net loss of only about 1% (12
million ha) since 1953. Most of these reductions have
come from withdrawals of public timberland for
wilderness or other non-timber uses.
A wide variety of silvicultural practices and
management intensities are used across the country.
About 11% of U.S. timberlands are plantations, with
two-thirds occurring in the southern states (Smith
et al., 2001). Nearly all tree species planted in
commercial forests are native to the regions in which
they are planted. About 58% of the volume of growing
stock is in softwoods, and the remaining 42% is in
hardwoods. Nearly all (90%) of the hardwood growing
stock is in the eastern states. About 68% of the
softwood growing stock is in western states, 22% in
the southern states, and 10% in northern states.
U.S. forests are an important part of the economy.
It is estimated that every forest-related job produces
an additional two jobs, therefore about 4 million jobs
are tied to the wood and paper industry. In addition,
recreational uses of the forest for hiking, camping,
fishing, hunting, and other non-timber uses continues
to grow, especially public lands, providing substantial
additional economic benefits in many parts of the
country (Loomis and Richardson, 2001).
The management of unwanted or competing
vegetation is vital to successful forest management
across the U.S. (Walstad and Kuch, 1987). Forests in
each region (Northwest, Southeast, Northeast, and
Lake States) have unique vegetation management
problems that can substantially reduce the growth
and survival of desired trees. Results from the longest
running studies (10–30 years) among these regions
suggest that gains in wood volume yield from
effectively managing forest vegetation are from 30 to
300% for major commercial tree species (Wagner et
al., 2004). Although there is no national tracking
system for the specific methods used to manage
forest vegetation, herbicides have been the primary
tool used to manage forest vegetation since the 1960’s
(Shepard et al., 2004; Wagner et al., 2004).
Despite their demonstrated safety, effectiveness,
and relatively low cost, the use of herbicides on
forestland has generated substantial public
controversy over the past several decades. Much of
the concern was initiated by the book “Silent Spring”
(Carson, 1962) and perpetuated with the use of
phenoxy herbicides (Agent Orange) by the U.S.
government during the Vietnam War (Walstad and
Dost, 1986). Perceived risks associated with using
herbicides in North American forests persist today,
and most of the other methods of vegetation
management are perceived as less risky and more
acceptable (Wagner et al., 1998). Pressure to reduce
or eliminate herbicide use has been most intense on
public forestlands, and as a result, relatively little
herbicide use occurs today on federal and state
forests for commercial timber production.
Controversy over the use of herbicides has
encouraged forest researchers and managers to develop
and use alternatives to herbicides, as well as develop
integrated approaches to forest vegetation manage-
ment (Wagner, 1993). Alternatives to herbicides for
managing forest vegetation include prescribed fire,
mechanical equipment, manual cutting, mulches,
grazing animals, and cover cropping (Harrington and
Parendes, 1993; Wagner, 1993; Comeau et al., 1996;
Wagner et al., 2001). These methods are often used
together with herbicides in many U.S. forests.
Depending on the circumstances, some of these
methods can be used in place of herbicides or reduce
the overall amount of herbicide use. Although not well
documented, experience suggests that when appro-
priately applied in some circumstances, alternative
methods can be just as effective as herbicides for
reducing competition and increasing stand growth,
but generally at substantially greater financial cost
than with herbicides. There also are many conditions
where alternatives to herbicides are not physically
possible, practical, available, or affordable. In addition,
many of the environmental and human health risks
of alternative methods are less well understood, and
are probably far worse in many situations, than for
Southern African Forestry Journal – No. 207, July 2006 75
In addition to the use of alternatives to herbicides,
there also has been a strong interest in developing
and promoting integrated forest vegetation
management (IFVM) approaches in U.S. forestry.
More recently efforts at promoting IFVM have come
from new systems of sustainable forest certification
established by various organisations. These systems
have been developed and are being promoted as a
means to improve the sustainability of forest
management practices across the U.S. and
internationally. The two most popular systems in
the U.S. are the Sustainable Forestry Initiative
(SFI) and the FSC. There are currently about 39
million ha certified under the SFI standard (SFI,
2003) and 3.8 million ha certified under the FSC
standard (FSC, 2004). SFI requires that forest
managers “minimise chemical use” and “use
integrated pest management where feasible” (SFI,
2002). FSC is more restrictive, stating that forest
managers are required “to adopt non-chemical
methods of pest management” and “to avoid and
move away from chemical pesticides wherever
possible,” and that “well-designed integrated pest
and vegetation management” be used an essential
part of their policy.
Despite the demand for IFVM, the principles,
methods, approaches, technologies, and scientific
information needed to implement IFVM are still in
their infancy. Considerable research is needed to
make IFVM, as it is currently conceived, a reality in
U.S. forests. Unfortunately, the same government,
industry, environmental, and forest certification
organisations demanding that reduced herbicide use
and IFVM be a firm policy on U.S. forestlands, are
doing little to support needed research this area. As
a result, herbicide use continues to be the primary
technology for managing forest vegetation (Shepard,
et al., 2004; Wagner et al., 2004), and many of the
principles of IFVM described above lack the scientific
and practical underpinnings required to put them
into practice.
Forestry is vital to each country reviewed, with the
type practised and forest products produced varying
according to the internal and external social,
ecological and economic needs of that country. Active
management of these forests is seen as critical to
ensure the sustained maintenance of both timber
and non-timber products. The management of
vegetation, whether for optimising growth,
eradication of exotics, or the maintenance of
biodiversity, is regarded as one of the most important
components of this process, and as such, has become
fully integrated within forest management as a
whole. This increased emphasis on the active
management of vegetation has resulted in changes
in the methods employed.
Despite the obvious attractions of utilising
herbicides, most countries have at some stage been
under pressure to regulate and reduce their use. The
degree of progress in finding research solutions and
their adoption varies from country to country. The
importance attached to reducing herbicide use also
varies, and is reflected in the steps taken to bring
change. For example, in Sweden and France there
has been limited herbicide use from the 1970’s,
whereas in South Africa, India and China,
opportunities exist to increase herbicide use,
particularly where the continued availability of
subsidised, or rural-based labour for manual
vegetation control operations is uncertain.
Among the countries reviewed, there appear to
have been three general approaches adopted to reduce
the use of herbicides. These are the continued use of
appropriate herbicides alone, but at lowered rates;
the use of alternative weed control methods to the
total exclusion of herbicides; or the continued use of
appropriate herbicides at lowered rates in combination
with alternative weed control methods.
Regardless of external pressure from governments
and non governmental pressure groups, a reduction
in herbicide use has occurred in many parts of the
world (for those countries where herbicides are still
used), through close co-operation between timber
growers, chemical companies and the country’s
regulatory bodies. Most countries have regulatory
processes in place that prevent using new herbicides
with harmful biological effects, for example high
mobility combined with long persistence and
significant health or ecological risk. Increasingly,
older active ingredients that pose a threat of
significant adverse environmental impact are also
being reviewed. In addition, the chemical industry
has continued to develop chemicals with more
attractive environmental profiles. The following
modifications have also reduced the amounts of
herbicides used: a reduction in the area treated; a
switch from high to low dosage products; the
introduction of highly active herbicides; reducing
application rates; removal of inactive isomers from
racemic mixtures; increased sprayer precision;
regulation of maximum dosage rates and maximum
number of applications. Similar modifications have
also occurred within the agricultural sector (Bellinder
et al., 1994; Lawson, 1994).
Although the basic principles of the need for
vegetation management when establishing trees
stretch back to at least the seventeenth century
(Evelyn, 1670; ECGPH, 1998), in modern times
research into understanding the underlying principles
behind weeding decisions may have been delayed due
to the development of herbicides which provided a
cheap, effective solution to the problem of competing
vegetation. Most knowledge on weed interference in
young plantations has come from empirical research
with herbicides (Richardson, 1993), focusing mainly
on tree crop response, herbicide type, application
rate, and degree of vegetation removal. Alternatives
to herbicides that have been developed and practised
include manual (hoeing/grubbing, slashing),
Southern African Forestry Journal – No. 207, July 2006
mechanical (rotovating, scalping), physical (organic
and inorganic mulches, thermal, inter- and smother-
cropping), biological and cultural methods. However,
these various vegetation control methods have, to a
large extent, been developed independently of each
other and consequently the technology of non-
herbicide treatments is not as advanced as that for
herbicides. Burnside (1993) suggests weed scientists
need to be pro-active and develop mechanical, cultural,
biological, and integrated weed management
research, otherwise they will continue to waste time
on defensive research and debating with environ-
mentalists. The practice of forest vegetation
management without herbicides requires more skill
than that with herbicides and tends to be less effective
and more difficult to prescribe, largely because a
forester must understand more of the biology of the
system (Harrington, 1993). Aspects such as
interference from competing vegetation, their ecology,
growth and behaviour have received less attention
(Nambiar, 1990; Collet et al., 1996). To match
appropriate vegetation control practices to soil, site
and species requirements, greater consideration needs
to be given to site quality and vegetation-tree
interactions (Neilsen and Wilkinson, 1990; Lowery
et al., 1993; Richardson et al., 1996). It is also
unlikely that any non-herbicide method applied in
isolation will bring about the desired effect, but
rather a combination of two or more methods, and
may even require the adoption of a totally new
species selection or silvicultural system.
Elmore (1992) suggests that scientists need to
advocate weed science by presenting the various
alternatives for controlling weeds, including both
non-chemical and chemical methods. Implicit within
these approaches is the principle associated with
integration, whereby appropriate technologies are
combined into an integral whole. It may be that the
greater the variety of techniques employed, the
smaller their individual importance and, by the
same token, the smaller their potential for
accumulation in or impact on the environment or the
development of resistance (Harr, 1992). Wagner
(1994) defines integrated forest vegetation
management (IFVM) as “managing the course and
rate of forest vegetation succession to achieve
silvicultural objectives by integrating knowledge of
plant ecology with a wide variety of complementary
methods that are ecosystem based, economical, and
socially acceptable.” Key elements of IFVM described
by Wagner (1994) involve forest managers 1) adopting
new perspectives about forest management, 2)
incorporating autecological information into
management strategies as a means of prevention, 3)
using economic or other thresholds before taking
management action, 4) enlisting a wider array of
complementary methods for vegetation control, and
5) more fully considering public concerns in the
design of vegetation management programs. Comeau
et al. (1996) suggest that IFVM (like Integrated Pest
Management) involves five steps: 1) problem
identification or diagnosis, 2) specifying injury and
treatment thresholds, 3) monitoring and predicting
vegetation development and young stand dynamics,
4) selecting treatment options, and, 5) evaluating
treatment effectiveness and impacts. Although many
countries have subscribed to the general principles of
IFVM, more research into specific strategies is
required. At present, where IFVM is practised, it
may be occurring by default rather than as part of
any formalised plan, or there may only be partial
integration at various levels, rather than total
integration, with the forestry system as a whole.
Challenges facing reduced herbicide use in
forest vegetation management
This review suggests that further work is required
on the following aspects:
Accurate quantification of changes in herbicide
use over time (increased or decreased product
number and quantities used).
Determination of the fate of herbicides currently
used in forestry, and the significance thereof
(rather than using agriculturally based data).
Enhanced research developing alternatives to
herbicides, and assessing the ecological and
economic impact of these alternatives.
Innovation regarding the dissemination of current
FVM information such that holistic and informed
decisions regarding the importance of different
vegetation practices (including herbicides) can
be made.
Where appropriate, innovation is also needed
regarding the implementation of viable
alternatives to herbicides through IFVM.
Refinement of the underlying principles of IFVM
within different silvicultural systems and
enhanced research of the highest priority
components of IFVM.
Refinement of vegetation management standards,
the use of alternatives, and limitations on the
use of herbicides in evolving forest certification
systems being implemented in various parts of
the world.
Education of the public, based on research that
has already been conducted, regarding the role
of appropriate herbicide use for managing
ABARE (Australian Bureau of Agricultural and Resource
Economics), 2004. Australian forest and wood products
statistics. Canberra ACT, Australia, Internet: http:// (consulted: May 2004)
ADAMS, P.R., 2004. Competition for soil water and nitrogen
between Holcus lanatus L. and young Eucalyptus globulus
Labill. Ph.D. dissertation, University of Tasmania, Hobart,
304 pp.
BAI, J., 1993. Technology for cultivating fast-growing and
Southern African Forestry Journal – No. 207, July 2006 77
high-yield eucalyptus plantations. China Science and
Technology Press, Beijing, 65 pp.
BARBORA, A.C., 2001. Weed control in tea plantations: Current
scenario in north-east India. In Proceedings: Alien weeds in
moist tropical zones: banes and benefits. K.V. SANKARAN,
S.T. MURPHY and H.C. EVANS (eds). Kerala Forest Research
Institute, 2-4 November 1999. Kerala Forest Research
Institute and CABI Bioscience, UK, pp. 107-111.
BARTHOD, C., 1994. Produits agropharmaceutiques en forêt –
22 questions, 22 réponses. Paris, DERF, IDF, ONF, 72 pp.
BARTHOD, C. and LANDMANN, G., 2002. Pourquoi gérer la
végétation forestière? Revue Forestière Française, 54(6):
1994. Percentage-driven government mandates for pesticide
reduction: the Swedish Model. Weed Technology, 8: 350-359.
BESSIÈRE, F., MOREL, M. and JEAN, R., 2002. Structure de
la propriété forestière 1999. Paris, Centre de documentation
et d’information Agreste, No.144, 94 pp.
BOARDMAN, R., 1988. Living on the edge – the development
of silviculture in South Australian pine plantations. Australian
Forestry, 51: 135-156.
BOOMSMA, D.B., 1982. Herbicide useage in the establishment
of coniferous plantations in Australia and New Zealand. In
Proceedings: Establishment of coniferous plantations. K.R.
SHEPHERD and R.O. SQUIRE (eds). Mt Gambier, South
Australia, pp. 59-73.
BOOMSMA, D.B. and HUNTER, I.R., 1990. Effects of water,
nutrients and their interactions on tree growth, and
plantation forest management practices in Australiasia: A
review. Forest Ecology and Management, 30: 455-476.
BROWN, C. and DURST, P.B., 2003. State of Forestry in the
Asia and the Pacific – 2003. Status, changes and trends. RAP
Publication 2003/22. FAO Regional Office for Asia and the
Pacific, Bangkok, 67 pp.
BURNSIDE, O.C., 1993. Weed science-The step child. Weed
Technology, 7: 515-518.
Application of Forest Herbicides by Product and Province/
Territory, 1988-2002. National Forestry Database Program,
Ottawa, Ontario, Canada. Internet:
(consulted: September 2004).
CARSON, R., 1962. Silent spring. Houghton-Mifflin, Boston,
MA, 368 pp.
CHAPMAN, H.H., 1931. Forest Management. Lyon Company,
New York, pp. 75-80.
CAZETTES, A., JEAN, R. and MOREL, M., 2002. Statistiques
forestières en 2001. Paris, Centre de documentation et
d’information Agreste, No.147, 85 pp.
CHOUDHURY, A.K., 1972. Controversial Mikania (climber) –
a threat to forest and agriculture. Indian Forester, 99: 43-48.
COLINOT, A., 2003. Des indicateurs stables pour une gestion
durable. Forêt-entreprise, 150: 17-44.
COLLET, C., FROCHOT, H. and GUEHL, J.M., 1996. Growth
dynamics and water uptake of two forest grasses in their
growth strategy and potentially competing with forest
seedlings. Canadian Journal of Botany, 4: 1555-1561.
COMEAU, P.G. and SPITTLEHOUSE, D.L., 1993. Micro-
environmental changes following forest vegetation
management. In Proceedings: Forest vegetation Management
without Herbicides. T.B. HARRINGTON and L.A.
PARENDES (eds). Oregon State University, Corvallis,
February 18 – 19, 1992, pp. 4-9.
J.O. and GILKESON, L.A., 1996. Integrated Forest Vegetation
Management: Options and Applications. In Proceedings of
the fifth B.C. Forest Vegetation Managemetn Workshop,
November 29 and 30, 1993, Richmond, B.C., FRDA Report
No. 251, Canadian Forest Service and B.C. Ministry of
Forests, Victoria, B.C.
COUSENS, R., 1996. Design and interpretation of interference
studies: Are some methods totally unacceptable? New Zealand
Journal of Forestry Science, 26: 5-18.
CSFA (China State Forestry Administration), 2003. Report on
Forestry Development in China. China Forestry Publishing
House, Beijing, 124 pp.
ECGPH (The Editing Committee of The Guangdong Province
History), 1998. The Annals of Guangdong Province –
Forestry. GuangDong People’s Publishing House,
Guangzhou, Guangdong, China, 124 pp.
ELMORE, C.L., 1992. Weed science extension in transition.
Weed Technology, 6: 171-176.
EVANS, H.C., 2001. Classical biological control: A tailor made
strategy for the management of alien weeds. In Proceedings:
Alien weeds in moist tropical zones: banes and benefits. K.V.
SANKARAN, S.T. MURPHY and H.C. EVANS (eds). Kerala
Forest Research Institute, 2-4 November 1999. Kerala Forest
Research Institute and CABI Bioscience, UK, pp. 35-41
EVELYN, J., 1670. Sylva, or a discourse of forest trees, and the
propagation of timber in His Majesties Dominions. Second
FENG, S., 2001. A preliminary report on the weeding experiment
of glyphosate weed killers on young forest lands. Journal of
Fujian, Forestry Science and Technology, 28: 28-30.
FORESTRY COMMISSION, 2003. Forestry facts and figures.
Forestry Commission, Edinburgh.
commercial timber resources and primary roundwood
processing in South Africa. Directorate Forestry Technical
and Information Services, Pretoria, South Africa.
MURDOCK, E.C., 1994. Selection of herbicide alternatives
based on probable leaching to groundwater. Weed
Technology, 8: 6-16.
WEHRLEN, L., 2002a. La gestion de la vegetation
accompagnatrice: état et perspective. Revue Forestière
Française, 54(6): 505-520.
KOERNER, W., 2002b. Using cover plants mixtures to favour
tree establishment in afforestation: an alternative to repeated
herbicides or mechanical vegetation controls? In Proceedings:
Fourth International Conference on Forest Vegetation
(eds). INRA, Nancy, 17-21 June 2002, pp. 233-235.
FSC (Forest Stewardship Council), 2002. Chemical Pesticides in
Certified Forests: Interpretation of the FSC Principles and
Criteria. FSC International Policy, FSC-IP-0001, Revised
and Approved July 2002. Forest Stewardship Council,
International Center. Forest Stewardship Council, Oaxaca,
México. Internet: (consulted: May 2004).
FSC (Forest Stewardship Council), 2004. Forests certified by
FSC – accredited certification bodies. Forest Stewardship
Council, International Center. Bonn, Germany. Internet: (consulted: May 2004).
GAMA, A., 2002. Herbicides et débroussaillants en forêt.
Evolutions prochaines des homologations. Forêt-entreprise,
147: 51-53.
GAMA, A., FROCHOT, H. and DELABRAZE, P., 1987. Phytocides
en sylviculture. Nogent-sur-Vernisson, Cemagref, INRA,
117 pp.
SMETHURST, P. and GAVA, J.L., 2004. Silvicultural effects
on the productivity and wood quality of eucalypt plantations.
Forest Ecology and Management, 193(1-2): 45-61.
GAVA, J.L., 2002. Manejo de resíduos vegetais e preparo de
solo. In Conservação e cultivo de solos para plantações
florestais. J.L.M. GONÇALVES and J.L. STAPE (eds).
Piracicaba, IPEF, pp. 131-204.
HALLSBY, G. and ÖRLANDER, G., 2004. A comparison of
mounding and inverting to establish Norway spruce on
podzolic soils in Sweden. Forestry, 77: 107-117.
HARR, J., 1992. The role of industry in the future of weed
science. Weed Technology, 6: 177-181.
HARRINGTON, T.B., 1993. Concluding Remarks. In
Proceedings: Forest vegetation Management without
Herbicides. T.B. HARRINGTON and L.A. PARENDES (eds).
Oregon State University, Corvallis, February 18 – 19, 1992,
pp. 128-129.
HARRINGTON, T.B. and PARENDES, L.A., 1993. Forest
vegetation Management without Herbicides. Proceedings of
a workshop held at Oregon State University, Corvallis,
February 18 – 19, 1992.
HE, S., LIU, S. and JUN, Q., 2000. Applied technology and
efficiency of herbicide use in forest tending. Forest Science
and Technology, 9: 28-29.
HSC, 1995. The safe use of pesticides for non-agricultural
purposes. Approved code of practice. HSE Books, Suffolk.
Southern African Forestry Journal – No. 207, July 2006
IFN (Inventaire Forestier National), 2004. Rapport d’activité
2003. Nogent-sur-Vernisson, IFN, 40 pp.
JARVEL, L. and PALLETT, R., 2002. Weed composition in
relation to site in re-established pine compartments on the
Mpumalanga Escarpment, South Africa. Southern African
Forestry Journal, 196: 15-20.
REYNOLDS, P.E., 1998. The Fallingsnow Ecosystem Project:
Documenting the consequences of conifer release alter-
natives. Journal of Forestry, 96(11): 20-27.
LAUTENSCHLAGER, R.A. and SULLIVAN, T.S., 2002. Effects
of herbicide treatments on biotic components in regenerating
northern forests. The Forestry Chronicle, 78(5): 695-731.
LAWSON, H.M., 1994. Changes in pesticide usage in the United
Kingdom: Policies, results and long-term implications. Weed
Technology, 8: 360-365.
LITTLE, K.M. and DYER, C., 2002. Some issues associated with
the commercial implementation of weed management
recommendations. Southern African Forestry Journal, 195:
LITTLE, K.M. and ROLANDO, C.A., 2001. The impact of
vegetation control on the establishment of pine at four sites
in the summer rainfall region of South Africa. Southern
African Forestry Journal, 192: 31-40.
LITTLE, K.M. and ROLANDO, C.A., 2004. Weed-induced
eucalypt growth suppression: Results from 33 trials linking
the onset of tree growth suppression with management,
physiographic and climatic factors. ICFR Bulletin Series,
Institute for Commercial Forestry Research, Pieter-
maritzburg, South Africa (In review).
LITTLE, K.M. and SCHUMANN, A.W., 1996. A new systematic
trial design for the optimisation of interspecific weed control.
In Proceedings: Eleventh Australian Weeds Conference.
R.C.H. Sheperd (ed). Frankston, Weed Science Society of
Victoria Inc., pp. 440-444.
LITTLE, K.M., SCHUMANN, A.W. and NOBLE, A.D., 2002.
Performance of a Eucalyptus grandis x E. camaldulensis
hybrid clone as influenced by a cowpea cover-crop. Forest
Ecology and Management, 168: 43-52.
LITTLE, K.M., VAN STADEN, J. and CLARKE, G.P.Y., 2003a.
Eucalyptus grandis x E. camaldulensis variability and intra-
genotypic competition as a function of different vegetation
management treatments. New Forests, 25: 227-242.
LITTLE, K.M., VAN STADEN, J. and CLARKE, G.P.Y., 2003b.
The relationship between vegetation management and the
wood and pulping properties of a Eucalyptus hybrid clone.
Annals of Forest Science, 60(7): 673-680.
LOOMIS, J.B. and RICHARDSON, R., 2001. Economic Values
of the U.S. Wilderness System: Research Evidence to Date
and Questions for the Future. International Journal of
Wilderness, 7(1): 31-34.
1993. Vegetation management in tropical forest plantations.
Canadian Journal of Forest Research, 23: 2006-2014.
LU, X., CHEN, S. and LU, Q., 1999. Use of herbicides in establish-
ing forest-fire break belts. Forest Science, Technology and
Development, 2: 46-47.
MASON, B., KERR, G. and SIMPSON, J., 1999. What is
continuous cover forestry? Forestry Commission Information
Note 29. Forestry Commission, Edinburgh.
MCCORMACK, Jr., M.L., 1994. Reductions in herbicide use for
forest vegetation management. Weed Technology, 8: 344-
MURPHY, S.T., 2001. Alien weeds in moist tropical zones of
India. In Proceedings: Alien weeds in moist tropical zones:
banes and benefits. K.V. SANKARAN, S.T. MURPHY and
H.C. EVANS (eds). Kerala Forest Research Institute, 2-4
November 1999. Kerala Forest Research Institute and CABI
Bioscience, UK, pp. 20-27.
NAIR, P.N., 1973. The effect of gramoxone application on
Eupatorium odoratum. Indian Forester, 99: 43-48.
NAMBIAR, E.K.S., 1990. Interplay between nutrients, water,
root growth and productivity in young plantations. Forest
Ecology and Management, 30: 231-232.
NATURAL RESOURCES CANADA, 2004. The State of Canada’s
Forests 2002-2003. Natural Resources Canada, Ottawa,
Ontario, Canada. Internet:
(consulted: May 2004).
NAVAS, M.-L., 1991. Using plant population biology in weed
research: a strategy to improve weed management. Weed
Research, 31: 171-179.
NEILSEN, W.A. and WILKINSON, G.R., 1990. Eucalypt sawlog
plantations in Tasmania, prospects and problems. In Prospects
for Australian plantations. J. DARGAVEL and N. SEMPLE
(eds). Australian National University, Canberra, pp. 550-
Facts and Figures 2003/2004. New Zealand Forest Owners
Association Inc, Wellington, 27 pp.
NILSSON, U. and ÖRLANDER, G., 1999. Vegetation
management on grass dominated clearcuts in southern
Sweden. Canadian Journal of Forest Research, 29: 1015-
NORMAN, P., 1997. The Montreal process criteria and indicators
– A framework for monitoring the conditions of Queensland’s
forests. In Sustainable forest management technical report
1997/01. Assessing and monitoring condition of native
forests in Quensland. P. NORMAN and C. WITTE (eds).
Department of Natural Resources, Brisbane, pp. 1-11.
OBSER, A., 1998. Criteria and indicators of sustainable forest
management and related certification schemes. Interor-
ganizational processes of implementation in global forestry.
Paper presented to the 39
Annual Convention of the
International Studies Association, Minneapolis, Minnesota,
USA, 17-21 March, 1998. Universität Leipzig, Germany.
WILHELMSSON, C., 1998. Inverting site preparation increases
growth of Norway spruce and Lodgepole pine seedlings.
Scandinavian Journal of Forest Research, 13: 160-168.
ÖRLANDER, G. and NORDLANDER, G., 2003. Effects of field
vegetation control on pine weevil (Hylobius abietis) damage
to newly planted Norway spruce seedlings. Annals of Forest
Science, 60: 637-643.
RAMAKRISHNAN, P.S., 2001. Biological invasion as a
component of global change. The Indian context. In
Proceedings: Alien weeds in moist tropical zones: banes and
benefits. K.V. SANKARAN, S.T. MURPHY and H.C. EVANS
(eds). Kerala Forest Research Institute, 2-4 November 1999.
Kerala Forest Research Institute and CABI Bioscience, UK,
pp. 28-34.
RAY, J. and RICHARDSON, B., 1995. Vegetation management
in radiata pine plantations. New Zealand Forest Research
Institute Report, Rotorua (unpublished).
RICHARDSON, B., 1993. Vegetation management practices in
plantation forests in Australia and New Zealand. Canadian
Journal of Forest Research, 23: 1989-2005.
COKER, G., 1996. Mechanisms of Pinus radiata growth
suppression by some common forest weed species. New
Zealand Journal of Forest Science, 26: 421-437.
Pinus radiata growth benefits from spot weed control in
Kinleith forest. In Proceedings: Fiftieth New Zealand Plant
Protection Conference, 50: 369 – 372.
B., 1997b. Spraysafe manager: A decision support system for
application of herbicides in forestry. In Proceedings: Fiftieth
New Zealand Plant Protection Conference, 50: 539.
SANKARAN, K.V., 1999. Eucalyptus plantations in the
monsoonal tropics-Kerala, India. In Proceedings: Site
management and productivity in tropical plantation forests.
Workshop held in Pietermaritzburg, South Africa, February
16-20, 1998, CIFOR, Indonesia, pp. 45-51.
V., 2002. Integrated management of the alien invasive weed
Mikania micrantha in the Western Ghats. KFRI Research
Report No. 202. Kerala Forest Research Institute, India, 51
SFI (Sustainable Forestry Initiative), 2002. Sustainable Forestry
Initiative (SFI) Program, 2002-2004 Edition. American Forest
and Paper Association, Sustainable Forestry Initiative.
Washington D.C., USA. Internet:
(consulted: May 2004).
SFI (Sustainable Forestry Initiative), 2003. 2003 Measurable
progress data. American Forest and Paper Association,
Sustainable Forestry Initiative, Washington D.C., USA.
Internet: (consulted: May 2004).
Forestry herbicides in the United States: An overview.
Wildlife Society Bulletin, 32: 1020-1027.
Southern African Forestry Journal – No. 207, July 2006 79
J.L. and GAVA, J.L., 1997. Weed proliferation in eucalypt
stands established under minimum and intensive site
preparation. In Proceedings: Silvicultura e melhoramento
de eucaliptos. IUFRO conference on silviculture and
improvement of eucalypts, Salvador, Brazil, 24–29 August
1997, pp. 234-241.
SINGH, S.P., 2001. Biological control of invasive weeds in India.
In Proceedings: Alien weeds in moist tropical zones: banes
and benefits. K.V. Sankaran, S.T. Murphy and H.C. Evans
(eds). Kerala Forest Research Institute, 2-4 November 1999.
Kerala Forest Research Institute and CABI Bioscience, UK,
pp. 11-19.
R.M., 2001. Forest Resources of the United States, 1997.
United States Forest Service, General Technical Report NC-
219. Washington D.C., USA. Internet:
(consulted: May 2004).
Statistical Yearbook of Forestry. The National Board of
Forestry, Jönköping.
THOMPSON, D.G. and PITT, D.G., 2003. A review of Canadian
forest vegetation management research and practice. Annals
of Forest Science, 60: 559–572.
R., 2003. Restoration of native woodland on ancient woodland
sites. Forest Service / Forestry Commission, Edinburgh.
ALVARENGA, S.F., 1999. Brachiaria decumbens manage-
ment and effects on the crop development of Eucalyptus
grandis. Scientia Forestalis, 55: 129-141.
UKWAS, 2000. Certification standard for the UK woodland
assurance scheme. UKWAS support unit, Forestry
Commission, Edinburgh.
VON GADOW, K. and BREDENKAMP, B., 1992. Forest
Management. Academica, Pretoria, pp. 1-6.
WAGNER, R.G., 1993. Research directions to advance forest
vegetation management in North America. Canadian Journal
of Forest Research, 23: 2317-2327.
WAGNER, R.G., 1994. Toward integrated forest vegetation
management. Journal of Forestry, 92: 26-30.
LEWIS, W. and TER-MIKAELIAN, M.T., 1995. Vegetation
Management Alternatives Program 1994–95 Annual Report.
Ontario Ministry of Natural Resources, Queen’s Printer for
Ontario, p. 99.
WAGNER, R.G., BELL, F.W. and CAMPBELL, R.A., 2001.
Vegetation management. In Regenerating the Canadian
forest: principles and practice for Ontario. R.G. WAGNER
and S.J. COLOMBO (eds). Fitzhenry and Whiteside,
Markham, Ontario, Canada, pp. 431-457.
1998. Public perceptions of risk and acceptability of forest
vegetation management alternatives in Ontario. Forestry
Chronicle, 74: 720–727.
K., 2006. The role of vegetation management for enhancing
productivity of the world’s forest. Forestry, 79: 57-79.
SHIVER, B.D., 2004. The role of herbicides for enhancing
forest productivity and conserving land for biodiversity in
North America. Wildlife Society Bulletin, 32(4): 1028-1041.
WALSTAD, J.D. and DOST, F.N., 1986. All the king’ horses and
all the king’s men: the lessons of 2,4,5-T. Journal of Forestry,
84(9): 28–33.
WALSTAD, J.D. and KUCH, P.J., 1987. Vegetation management
for conifer production. John Wiley, New York, USA.
WANG, Y., GAO, Z., BO, M., HE, Y. and GAO, L., 2001. Recent
developments in chemical weed killer and its application in
forestry in China. Journal of Zhejiang Forest Science and
Technology, 21: 60-63.
C. and GAMA, A., 1994. Les herbicides en forêt, valise
pédagogique. Jeu de 59 transparents et guide à l’usage des
formateurs. ONF, CNFF, Cemagref, INRA, 70 pp.
WEI, R.-P., 2003. Merging ecological/environmental concerns
into sustainable management of short rotation plantations
in South China: practices by Sino-Forest Corp. In Proceedings:
Eucalypt Plantations – Research, Management and
Development. R-P. WEI and D-P. XU (eds). Guangzhou/
Zhaoqing, 1-6 September 2002, World Scientific, Singapore,
pp. 51-63.
WHITEHEAD, R., 2004. The UK pesticide guide 2004. British
Crop Protection Council / CABI publishing, Wallingford,
WILLOUGHBY, I., 1999. Future alternatives to the use of
herbicides in British forestry. Canadian Journal of Forest
Research, 29(7): 866-874.
and TROUT, R., 2004. Reducing pesticide use in forestry.
Forestry Commission Practice Guide. Forestry Commission,
Edinburgh, 140 pp.
WINCÈLIUS, F., 2002. Le phénomène météorologique et son
impact. Revue Forestiere Francaise sp. 2002 Après les
tempêtes, 21-30.
WYSE, D.L., 1992. Future of weed science research. Weed
Technology, 6: 162-165.
XU, X., JIN, X., HUANG, Y. and XU, G., 2003. A preliminary
report on use of glyphosates in tree planting and young stand
tending. Journal of Jiangsu Forestry Science and
Technology, 30: 31-32.
ZHANG, Q., 2003. Research on using herbicide for setting up
forest-fire breaks in Yihou Mountain forest area. Forest
Resource Management, 3: 40-43.
Southern African Forestry Journal – No. 207, July 2006
... The main aim of this practice was to reduce the competition for resources during the growth period with other vegetation in the same area (McCarthy et al. 2011). To do so, a greater use of chemicals was adopted in the form of artificial fertilizers, herbicides, and pesticides (Little et al. 2006;McCarthy et al. 2011). ...
Carotenoid pigments are deeply involved in forests’ response to environmental stressors. Imaging spectroscopy has been widely applied for predicting leaf total carotenoid content. However, distinguishing carotene and xanthophylls, which is essential for monitoring plants’ stress at a broad-scale, remains challenging. To achieve this, calibrating models using field spectroscopy is necessary for applications to drone, airborne, and satellite imagery. In this respect, this chapter presents a novel approach based on Machine Learning (ML), which involves comparing various algorithms applied to continuum-removed field reflectance data for estimating carotenoid contents in leaves of riparian forest species. The first section of the chapter outlines recent advances and pitfalls in carotenoid retrieval using remote sensing. The next section describes the proposed approach, including the description of the dataset, the principles of commonly-used ML algorithms, as well as their performance in distinguishing carotene and xanthophylls. Finally, the last section discusses the perspectives of upscaling the approach to imaging spectrometers towards broad-scale, operational monitoring of forests’ response to environmental stressors.
... This results in a reduction in the absorption of nutrients, water, and air. Weed and pesticides (Little et al. 2006;Moriaque et al. 2017;Bai et al. 2018) become more prevalent in these crops as they become nutrient deficient, whereas in the alkaline medium, most metals are not available for absorption like Fe, Zn, Cu, and Mn. Iron deficiency or iron chlorosis (Atera and Itoh 2011) commonly occur in alkaline soil. ...
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This work aimed to analyze the soil quality and heavy metal contamination in the Jumar watershed of Jharkhand and suggests possible measures that could be taken to guarantee suitable management practices. Therefore, in the present work, the soil sampling was done at 8 locations, selected based on site visit. The GPS coordinates of the sampling sites were noted. The soil samples were collected during pre-monsoon and post-monsoon seasons for 2017 and 2018 at a depth of 20 cm from the top. Water samples were collected from the river flowing closer to the sampling points. Then, soil quality parameters such as pH; electrical conductivity; bulk density; moisture content; and surface water quality parameters such as pH, EC, TDS, DO, COD, BOD, alkalinity, turbidity, and nutrients (N & P) were studied. For heavy metal analysis (Pb, Zn, Cu, As, Ni), both soil and water samples were analyzed using an inductive coupled plasma-optical emission spectrophotometer (ICP-OES). Statistical tools like descriptive statistics, multivariate analysis, principal component analysis, correlation coefficient, and ANOVA were applied using SPSS version 21. The data indicate that the values of moisture content varied between 22.06 and 45.7%, soil bulk density varied between 1.20 and 1.55 g/cm 3 , pH varied between 7.79 and 8.17, and EC varied between 116.66 and 207.08 μS/cm. The concentrations of heavy metals in the pre-monsoon season were higher (Zn 0.183 mg/l, Cu 0.09 mg/l, Ni 0.061 mg/l) than those in the post-monsoon season (Zn 0.17 mg/l, Cu 0.076 mg/l, Ni 0.138 mg/l). The water quality index found using pH, EC, TDS, DO, COD, BOD, alkalinity, turbidity, BOD, COD, nutrients, and heavy metals indicated that most sites had excellent water quality, especially in the pre-monsoon period. But in the post-monsoon period of 2017, the water quality index showed that water was in poor condition. Overall water quality was found to be good. It was found that the soil had very slight traces of heavy metals and was slightly alkaline indicating the need for better watershed management practices for the future. PCA showed that the component variables like pH and EC were principal components specially for both pre-monsoon seasons, whereas through ANOVA, it was found that the variable has strong relationship among themselves.
... A growing number of scientific publications and judicial actions contest glyphosate safety for the human health and the environment (Helander et al. 2012, Maggi et al. 2020, which have motivated some restoration practitioners to quit using this herbicide. However, the challenge of controlling competing plants, especially exotic alien grasses in tropical forest restoration, remains and alternatives to herbicides have just started to be developed (Little et al. 2006). ...
Competition with invasive grasses is one of the most important drivers of tree planting failures, especially in tropical forests. A widely disseminated weeding approach has been glyphosate spraying, the most used herbicide globally in forestry and ecosystem restoration. However, glyphosate use in restoration is highly controversial and requires further studies to elucidate its effects on restoration processes and the environment. We evaluated the use of glyphosate in riparian forest restoration and its impacts on tree planting costs, weed control efficiency, planted seedling performance, herbaceous and woody species regeneration, soil bacteria, and environmental contamination, using mowing treatments as a reference and based on a controlled experiment established in the Brazilian Atlantic Forest. Glyphosate spraying reduced by half and a third the accumulated aboveground biomass of, respectively, weeds in general and of the invasive grass Urochloa decumbens compared to mowing treatments, and it reduced the cost by half. The performance of planted tree seedlings was markedly favored by glyphosate spraying compared to mowing treatments, as expressed by improved seedling height (~twice higher), crown area (~5× higher), and basal area (~5× higher); the regeneration of both native woody and ruderal herbaceous plants were also enhanced. Neither glyphosate nor its metabolite Aminomethylphosphonic acid (AMPA) residues were detected in either water runoff or soil samples, but they were found at relatively high concentrations in the runoff sediments (from 1.32 to 24.75 mg kg‐1 for glyphosate and from 1.75 to 76.13 mg kg‐1 for AMPA). Soil bacteria communities differed before and after glyphosate spraying in comparison to mowing plots (without glyphosate). Glyphosate spraying was far more cost‐effective than mowing for controlling U. decumbens and greatly improved the performance of planted tree seedlings and natural regeneration, while not leaving residues in soil and water. However, the changes in the structure of bacterial communities and high concentration of glyphosate and AMPA residues in runoff sediments highlight the need for caution when using this herbicide in riparian buffers. We present alternatives for reducing glyphosate use and minimizing its risks in tree planting initiatives.
... During the early 1990s, hoeing and handpulling of weeds along the tree lines were rapidly replaced by the use of herbicides [166]. The introduction of herbicides did not lead to the total exclusion of labour-intensive weeding methods as most herbicides were applied by hand, either as broadcast or direct spray [167]. During this period, equipment such as hand-operated knapsack sprayers, motorized mist blowers, controlled droplet applicators (e.g. ...
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Purpose of Review The mechanization of silvicultural work on forest plantations is usually driven by a decreasing supply of motivated labour which increases its relative cost. Mechanization can also result in other advantages like increased effectiveness, higher efficiency, and improved working conditions. The purpose of our review is to examine the last few decades’ endeavours to mechanize the regeneration activities of plantation forestry in the southern and northern hemisphere. In this case, regeneration activities include (1) site preparation; (2) tree planting; and (3) stand tending until the crop trees are free from vegetative competition. Recent Findings Originally, the mechanization of silvicultural work commenced in the northern hemisphere, but over the past decades, the most notable progress has been made in the southern hemisphere plantation forests. Although soil preparation is largely mechanized across the globe, tree planting and stand tending activities lag behind because of factors such as global variations in the manner in which they are performed, higher level of complexity, and low-cost competitiveness compared with existing labour-intensive methods. Summary For mechanization of regeneration/silvicultural activities to progress, productive and adaptable machines will be required where economies of scale permit cost-efficient operations. These machines will probably have to be modified to the specific forestry context of different countries. Knowledge of the existing and state-of-the-art regeneration technologies available in both the northern and southern hemispheres is important for foresters to make informed decisions about the selection and application of mechanized regeneration systems.
... These pressures are reflected in the Forest Stewardship Council (FSC) certification schemes which focus on decreasing or eliminating the use of chemical herbicides. This is a major challenge for forestry and has led to a number of initiatives to reduce herbicide use such as more targeted application or the use of mulches and cover crops (Little et al., 2006;Willoughby et al., 2004). ...
... Atualmente, alguns produtos registrados não oferecem ideal grau de controle, são grupos não-seletivos, ou não são competitivos. Esta condição, juntamente com o alto preço dos herbicidas disponíveis e as preocupações ambientais, fez com que os proprietários florestais busquem por métodos alternativos para o manejo da vegetação (LITTLE et al., 2006). Sendo assim, a eficácia dos métodos deve ser analisada paralelamente ao possível impacto ambiental deles decorrentes, a fim de que, priorizando o baixo custo ou a eficácia, acabe-se por prejudicar o meio ambiente em longo prazo. ...
O objetivo deste trabalho foi comparar a atividade de eliminação de Eucalyptus sp. em uma área de preservação permanente de margem de rio, realizada pelos métodos mecânico, por meio de anelamento, e químico, com uso de uma cavadeira química. A área de estudo pertence a uma empresa florestal localizada no estado de São Paulo. Foram amostradas 15 árvores em cada método, sendo cinco por trabalhador, e cada trabalhador executou a atividade em ambos os métodos de trabalho. A análise técnica foi realizada por meio de um estudo de tempos, contemplando a fase propriamente dita da atividade, de modo a se verificar o tempo médio demandado em cada método. A análise de custos foi realizada por meio da determinação dos custos fixos e variáveis, bem como do custo de produção. A análise da eficácia foi realizada pela observação visual das árvores amostradas, a fim de se verificar possíveis sintomas indicativos de morte dos indivíduos. Os resultados mostraram que o método químico apresentou menor tempo demandado, onde a relação entre os dois métodos foi de 4,3 árvores inoculadas com o produto químico para cada 1 árvore anelada. O método químico apresentou maior custo operacional em relação ao método mecânico, devido principalmente à depreciação da cavadeira química e aos custos com o herbicida. Entretanto, devido à maior produtividade, o custo de produção no método químico se mostrou menor. Por fim, durante o período de quatro semanas de observação, foi comprovada a eficácia do método químico, devido à existência de sintomas indicativos de morte, como coloração marrom das folhas e sua queda parcial. No entanto, não se deve tomar a decisão final sem antes verificar o impacto ambiental do produto químico.
Life is dependent on forest cover. Many ecosystem services such as mitigation of climate change, protection of the watershed, maintenance of biogeochemical cycles, and control of environmental pollution may be achieved by a good forest cover. Because of the demands of a growing population, some devastating changes have occurred in land use, land cover, and resources utilization. Due to anthropogenic interference such as deforestation, overgrazing, cultivation with more fertilizers, urbanization, and industrialization, extreme climatic changes have occurred. Loss of wildlife species, extinction of microbial diversities, drought, eutrophication, sedimentation, and flash floods have become common. To manage resources sustainably and effectively, advanced technology of geospatial application is being utilized worldwide. Geospatial applications such as GIS and remote sensing methods, use of sensors, geostatic methods, spectral indices, and neural networking methods have made the processes from data collecting to developing plans for better greenery management much easier. This chapter aims to review the sustainable management strategies of vegetation cover and the challenges faced in this process. We review how remote sensing and GIS applications help in overcoming the various challenges of sustainable monitoring and management of vegetation and forest resources.
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This paper examines herbicide use in South African commercial plantations in 2017/18 across three climate zones (cool temperate − CT, warm temperate − WT and subtropical − ST) for three genera (eucalypts, pines and acacias) grown for two end-products (sawn timber and pulpwood). Herbicide information was obtained from 46 timber plantations owned by six forestry companies, comprising 343 872 ha surveyed. The herbicide survey was divided into three climate zones due to increased vegetation growth (and hence more herbicide use) on more productive ST sites compared to moderately productive WT sites, with the lowest vegetation growth on CT sites (lower productivity). The survey was further divided into three distinct vegetation management phases associated with plantation forestry (pre-establishment, re-establishment and post-establishment) to compare herbicide use bet ween genera grown on an annual basis. A total of 188 288 kg (or 0.55 kg ha⁻¹) of herbicide active ingredient (a.i.) was applied in the area surveyed. Glyphosate-based products accounted for 97% of all the herbicides applied, and metazachlor and triclopyr butoxy ethyl ester accounted for 2%. Overall, herbicide use per hectare on an annual basis was highest in the ST zone, followed by the WT and CT zones. For both the CT and WT zones, the general trend was that the pre-establishment phase received noticeably more herbicides, followed by the re- and post-establishment phases (pre>re>post). This trend remained similar for the genera grown (pre>re>post), with hardwoods receiving more herbicides than softwoods. In contrast, there was little difference in herbicide use between the re- and pre-establishment phases for the ST zone, with the post-establishment phase being noticeably less. Besides providing benchmark data related to herbicide use in South African plantations, future research should investigate the potential for a reduction in herbicide use in those regions, vegetation management phases and management regimes where it is highest.
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Efficient and cost-effective re-establishment practices are important parts of any sustainable forest re-establishment programme. Re-establishment activities include residue management (post-harvest slash), preparation of a planting position, planting, fertilisation and vegetation management. In South Africa, these activities are largely labour intensive, time-consuming and relatively costly. Although mechanisation of site preparation during afforestation was achieved in the mid to late 1990s, plantation re-establishment operations in South Africa have remained manually oriented. However, there have been notable technology developments over the past decade. Semi-structured interviews were conducted with 66 experts (grower company specialists, foresters, contractors and machine manufacturers) to get their perspectives on modernisation of re-establishment activities in South Africa. Frequency distribution and chi-square test analysis found that two-thirds of the experts believed that re-establishment activities had progressed in terms of technology over the past decade. This development was reported as primarily due to the need to improve health and safety (91%), increase production whilst reducing costs (89%), improve stand productivity (quality) (86%), mitigate social (mainly labour) risks (80%) and reduce prevalent negative environmental impacts (50%). Key barriers to modernisation were identified as the capital cost of equipment (65%), reduction in employment opportunities (44%) and low utilisation of equipment due to seasonality of silviculture work (18%). Experts indicated that the efficiency of mechanised re-establishment equipment can be affected negatively by residues, high stumps and compaction of the site after harvesting. The results of this study will assist forestry stakeholders to make informed decisions when planning and implementing modernised silviculture operations.
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Humid tropical forests are increasingly exposed to devastating wildfires. Major efforts are needed to prevent fire-related tipping points and to enable the effective recovery of fire-affected areas. Here, we provide a synthesis of the most common forest restoration strategies, thereby focusing on post-fire forest dynamics in the humid tropics. A variety of restoration strategies can be adopted in restoring humid tropical forests, including natural regeneration, assisted natural regeneration (i.e. fire breaks, weed control, erosion control, topsoil replacement, peatland rewetting), enrichment planting (i.e. planting nursery-raised seedlings, direct seeding) and commercial restoration (i.e. plantation forests, agroforestry). Our analysis shows that while natural regeneration can be effective under favourable ecological conditions, humid tropical forests are often ill-adapted to fire, and therefore less likely to recover unassisted after a wildfire event. Active restoration practices may be more effective, but can be costly and challenging to implement. We also identify gaps in knowledge needed for effective restoration of humid tropical forests after fire, hereby taking into account the ecosystems and socio-economic conditions in which these fires occur. We suggest to incorporate fire severity in future studies, to better understand and predict post-fire ecosystem responses. In addition, as fire poses a recurring and intensifying threat throughout the recovery process, more emphasis should be placed on post-restoration management and the prevention of fire throughout the different phases of the restoration process. Furthermore, as tropical wildfires are increasing in scale, establishing collaborative capacity and setting priorities for efficient resource allocation should become a major priority for restoration practitioners in the humid tropics. Finally, as global fire regimes are changing and expected to intensify in the context of climate change, land use and land cover change, we suggest to put continuous effort into fire monitoring and modelling to inform the development of effective restoration strategies in the long-run.
Il est paru au Journal Officiel du 18 août 2002 un avis qui présente la "liste des substances actives entrant dans la composition des préparations dont l'autorisation de mise sur le marché est retirée". Concernant les herbicides pour la forêt, on y trouve : dalapon, dichloprop, fosamine et hexazinone. Cette décision implique le retrait de l'autorisation de vente. Les dates sont variables selon les spécialités.
Weed Science Extension is in a period of change. Though there is decreased funding for extension in the United States and Europe, the number of programs including extension activities is increasing in developing countries as shown by World Bank funding. There is a perception problem with the name weed science; we need a strong, recognizable science name. Decreases in one-on-one contact method for teaching, fewer extension weed specialists, and the increased need for interdisciplinary projects to support Integrated Pest Management and Sustainable Agriculture will increase stresses on our positions. These factors also increase the challenge for weed specialists and extension advisors (agents) to become leaders in current programs, initiate new multidisciplinary programs, and choose those programs that will benefit our discipline. Our clientele and the method of communicating with them will change, presenting yet another challenge.
The agricultural-chemical industry has been offering solutions in plant protection for several decades. The primary role of Industry in weed control has mainly been to provide chemicals with increasingly attractive profiles regarding safe handling, ecological acceptance, and economical attractiveness. These objectives have been reached by significant developments, e.g. in rates, persistence, and specificity for non-target organisms. It is therefore safe to assume that in the year 2015 and beyond chemicals will continue to maintain a major role in weed control. However, as cropping systems and criteria for desirable control levels change, industry will have to change from a re-active to a pro-active participant in the development of integrated systems. Chemical solutions will be complemented by biological and agronomical methods and will be further supported by biotechnological successes in the crop area. In addition, it is anticipated that sophisticated computer models now in development will help exploit the potential of products as well as of integrated systems. Thus, fully integrated companies active in chemical, biological, and molecular-biological research and having branches in the agro-chemical as well as in the seed business will be especially suited to be driving forces in the changing world of modern weed control. The practice will ask for services much more than for single products. Industry will not only have to offer those services but at the same time assist in the education of growers to enable efficient use of the increasingly intricate methods of future weed control.
A brief evolutionary description is given of the development of the discipline of weed science in the United States. Topics discussed include public recognition of weed science, losses from weeds, allocation of resources, herbicide usage, and future predictions of the development of the discipline. Weed scientists have had a major impact during the past four decades in increasing crop yields and reducing labor requirements for controlling weeds in crop production systems. Weed scientists have been so effective that recognition of their contributions and impact have often been overlooked in academic institutions but not in private industries that have staffed for herbicide development.
Current United Kingdom (UK) government policy on pesticides is aimed at minimizing rather than arbitrarily reducing usage. It is to be achieved through a rigorous Approvals process, the setting of statutory maximum residue limits, regular monitoring, legislation on the safe use of pesticides on farms, and a core-funded research program on topics such as improved forecasting of pest infestations, more effective application techniques, alternative control strategies, integrated pest management and sustainable farming systems. Over the longer term these measures are expected to bring about substantial real decreases in pesticide usage, without the need to impose arbitrary reduction targets, such as have been implemented by several other European countries. Reductions in the usage of particular chemicals will also occur as a result of the implementation of European Community (EC) environmental legislation on pesticide levels in ground and drinking water and pesticide discharges into the North Sea. With herbicides, the tonnage of active ingredient applied in the UK declined substantially during the 1980s, due mainly to the increased use of products which were more biologically active at lower dosage rates than those they replaced. The actual percentage of crops sprayed remained at 95 to 100. Further reductions are likely in the 1990s, enhanced by factors such as dose-cutting by farmers in response to economic rather than environmental pressures and an increase in set-aside. Weed scientists are currently studying the long-term effects on weed population dynamics of reduced herbicide inputs in cereals, set-aside management, and more environmentally friendly, lower input rotations, as part of a wider program of research designed to provide government with scientifically based information upon which to decide future policies.
There is distinct regional variation in forestry uses of herbicides. Different land ownership patterns affect policies and practices, and crop tree species characteristics differ within and among regions. Recent decreases in land areas treated have been attributed to budget reductions, changes in operating conditions, and pressures from the general public. Factors affecting future reductions in amounts of herbicides used will include new chemistry, improved delivery technologies, incorporating vegetation management into all aspects of young stand silviculture, and employment of alternative methods.
"An important, controversial account ... of the way in which man's use of poisons to control insect pests and unwanted vegetation is changing the balance of nature." Booklist.
Herbicide technology has evolved with forest management in North America over the past 60 years and has become an integral part of modern forestry practice. Forest managers have prescribed herbicides to increase reforestation success and long-term timber yields. Wildlife managers and others interested in conserving biodiversity, however, have often viewed herbicide use as conflicting with their objectives. Do herbicides increase forest productivity, and are they compatible with the objectives of wildlife management and biodiversity conservation? Results from the longest-term studies (10–30 years) in North America suggest that the range of wood volume yield gains from effectively managing forest vegetation (primarily using herbicides) is 30–450% in Pacific Northwest forests, 10–150% in the southeastern forests, and 50–450% in northern forests. Most of the 23 studies examined indicated 30–300% increases in wood volume yield for major commercial tree species and that gains were relatively consistent for a wide range of site conditions. Meeting future demands for wildlife habitat and biodiversity conservation will require that society's growing demand for wood be satisfied on a shrinking forestland base. Increased fiber yields from intensively managed plantations, which include the use of herbicides, will be a crucial part of the solution. If herbicides are properly used, current research indicates that the negative effects on wildlife usually are short-term and that herbicides can be used to meet wildlife habitat objectives.