Conservation grazing
Encyclopedia
Conservation grazing is the use of semi-feral
or domesticated grazing
livestock
to maintain and increase the biodiversity
of natural or semi-natural grassland
s, heathlands, wood pasture
, wetland
s and many other habitat
s.
Conservation grazing is generally less intensive than practices such as prescribed burning, but still needs to be managed to ensure that overgrazing does not occur. The practice has proven to be beneficial in moderation in restoring and maintaining grassland and heathland ecosystem
s. The optimal level of grazing will depend on the goal of conservation, and different levels of grazing, alongside other conservation practices, can be used to induce the desired results.
s, grazing animals, herbivore
s, were a crucial part of the ecosystem. When grazers are removed, historically grazed lands may show a decline in both the density and the diversity of the vegetation. The history of the land may help ecologists and conservationists determine the best approach to a conservation project.
Historic threats to grasslands primarily began with land conversion to crop fields. However, this threat shifted to improper land management techniques and more recently to the expansion of woody species of plants due to a lack of management, and to climate change
. These threats hinder the ecological importance of grassland communities. Grasslands are a carbon sink, and benefit livestock. Ecologically, if managed properly, conservation grazing can help to restore these historic ecological assets. However, if the grazing levels reach too high, shrubs will persist over grassland.
In 1985, the US established the Conservation Reserve Program
(CRP), which gave money to farmers to leave land fallow, instead of using it for crops or grazing. It was argued that exclusion or use of moderate grazing would be an important factor in future decisions as to what to do with the land that was a part of the CRP program. The land could have varied uses in the future. The minimization of the effects of climate change has a lot to do with the sequestering of carbon, and expansive grasslands may play an essential role in this process. But also it could be used for the rotation of crops to the benefit of wildlife populations.
, habitat
, and plant community are desired to be maintained or restored. Grazing
is a beneficial tool used to create a grass and small shrub dominated area. Tasker and Bradstock found that grazed areas returned a lower vegetation complexity score than ungrazed, however this was mainly because tree species and shrubs produce higher complexity scores than grasses – the grazed areas were composed primarily of bunch grasses and the ungrazed were dominated by shrub
species. Certain areas that have been, historically, woody forest, may be chosen to be restored back to historical conditions, thus Tasker’s and Bradstock’s study would imply that wooded areas should remain ungrazed by livestock such as cattle.
Conservation practices such as grazing need to be monitored closely. If they are not, the practice can become overused and have an opposite effect than intended. Overgrazing may cause erosion
, habitat destruction, soil compaction
, or reduced biodiversity (species richness
).
One issue of controversy with grazing is whether conservation grazing is in fact beneficial to a grassland
community and what intensity of grazing management needs to be taken. Rambo and Faeth found that the use of vertebrates for grazing of an area would increase the species richness of plants by decreasing the abundance of dominant species
and increasing the richness of rarer species. The decrease in abundance may lead to a more open forest canopy and more room for other plant species to emerge.
to be enhanced as well as the native biodiversity
. A study by Loeser et al. showed that areas of high intensity grazing and grazer removal increased the biomass
of nonnative introduced species
. Both showed that an intermediate approach is the best method. The nonnatives did demonstrate that they were not as well adapted to the disturbances, such as drought
. This indicated that implementing controlled grazing methods would decrease the abundance of nonnatives in those plots that had not been properly managed.
Effects of grazing can also depend on the individual plant species and its response to grazing. Plants that are adapted to extensive grazing (such as that done by cattle) will respond quicker and more effectively to grazing than native species that have not had to cope with intense grazing pressure in the past. An experiment done by Kimball and Schiffman showed that grazing increased the cover of some native species but did not decrease the cover of nonnative species. The species diversity of the native plants was able to respond to the grazing and increase diversity. The community would become denser than originally with the increased biodiversity. (However, this may have been simply variance in plots due to the fact that the native and nonnative compositions were of different species between the grazed and ungrazed plots.)
and abundance of insects in grasslands. Land management in the form of grazing tends to decrease diversity with increased intensity. Kruess and Tscharntke attribute this difference to the increased height of grasses in the ungrazed areas. The study showed that the abundance and diversity of insects (such as butterfly adults, trap-nesting bees and wasps) were increased by increased grass height. However, other insects such as grasshoppers responded better to heterogeneity of the vegetation.
and the Desert Tortoise
. However, Kazmaier et al. found that the effect of moderate grazing on the Texas Tortoise
did not show a significant difference when comparing grazed and ungrazed plots.
Rabbits have been widely discussed due to their influences on land composition. Bell and Watson found that rabbits show grazing preference for different plant species. This preference can alter the composition of a plant community. In some cases, if the preference is for a non-native, invasive plant, rabbit grazing may benefit the community by reducing non-native abundance and creating room for the native plant species to fill. When rabbits graze in moderation they can create a more complex ecosystem, by creating more variable environments that will allow for more predator-competitor relationships between the various organisms. However, besides the effect on wild vegetation, rabbits destroy crops, compete with other herbivores, and can result in extreme ecological damage. Competition can be direct or indirect. The rabbits may specifically eat the competitions target food or it may inhibit the growth of grasses that other species eat. For example, rabbit grazing in the Netherlands inhibits tall grasses from becoming dominant. This in turn enhances the suitability of the pasture for Brent Goose
. However, they may benefit predators that do better in open areas, because the rabbits reduce the amount of vegetation making it easier for those predators to spot their prey.
wetlands degradation and loss of biodiversity had, at one point in time, been blamed on mismanaged grazing of both native and non-native ungulates and other grazers. A study done by Jaymee Marty of The Nature Conservancy
examined the effects on the vernal pools formed in California when grazers were removed. The results of the short study showed that areas where grazers were removed had a lower diversity of native grasses, invertebrates and vertebrates in the pools, with an increase in non-native grass abundance and distribution in the area. The study also demonstrated reduced reproduction success of individual species in the area, such as the Western Spadefoot Toad
and California Tiger Salamander
. Marty argues that this decrease is due to ecosystems adapting to historical changes in grazers and the effects they have. In other words, the historic ecosystem, theoretically, would have responded positively to the removal of cattle grazing, however, the system has adapted to the European introduced species and require now may require them for maintained diversity. In another study performed by Pyke and Marty, measurements showed that on average, vernal ponds on grazed land pooled longer than ungrazed areas and soil was more resistant to water absorption in the grazed areas.
Feral
A feral organism is one that has changed from being domesticated to being wild or untamed. In the case of plants it is a movement from cultivated to uncultivated or controlled to volunteer. The introduction of feral animals or plants to their non-native regions, like any introduced species, may...
or domesticated grazing
Grazing
Grazing generally describes a type of feeding, in which a herbivore feeds on plants , and also on other multicellular autotrophs...
livestock
Livestock
Livestock refers to one or more domesticated animals raised in an agricultural setting to produce commodities such as food, fiber and labor. The term "livestock" as used in this article does not include poultry or farmed fish; however the inclusion of these, especially poultry, within the meaning...
to maintain and increase the biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
of natural or semi-natural grassland
Grassland
Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...
s, heathlands, wood pasture
Wood pasture
Wood pasture is a historical European land management system in which open woodland provided shelter and forage for grazing animals, particularly sheep and cattle, as well as woodland products such as timber for construction and fuel, coppiced stems for wattle and charcoal making and pollarded poles...
, wetland
Wetland
A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....
s and many other habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
s.
Conservation grazing is generally less intensive than practices such as prescribed burning, but still needs to be managed to ensure that overgrazing does not occur. The practice has proven to be beneficial in moderation in restoring and maintaining grassland and heathland ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
s. The optimal level of grazing will depend on the goal of conservation, and different levels of grazing, alongside other conservation practices, can be used to induce the desired results.
History
For historic grasslandGrassland
Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...
s, grazing animals, herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
s, were a crucial part of the ecosystem. When grazers are removed, historically grazed lands may show a decline in both the density and the diversity of the vegetation. The history of the land may help ecologists and conservationists determine the best approach to a conservation project.
Historic threats to grasslands primarily began with land conversion to crop fields. However, this threat shifted to improper land management techniques and more recently to the expansion of woody species of plants due to a lack of management, and to climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...
. These threats hinder the ecological importance of grassland communities. Grasslands are a carbon sink, and benefit livestock. Ecologically, if managed properly, conservation grazing can help to restore these historic ecological assets. However, if the grazing levels reach too high, shrubs will persist over grassland.
In 1985, the US established the Conservation Reserve Program
Conservation Reserve Program
The Conservation Reserve Program is a cost-share and rental payment program under the United States Department of Agriculture , and is administered by the USDA Farm Service Agency . Technical assistance for CRP is provided by the USDA Forest Service and the USDA Natural Resources Conservation...
(CRP), which gave money to farmers to leave land fallow, instead of using it for crops or grazing. It was argued that exclusion or use of moderate grazing would be an important factor in future decisions as to what to do with the land that was a part of the CRP program. The land could have varied uses in the future. The minimization of the effects of climate change has a lot to do with the sequestering of carbon, and expansive grasslands may play an essential role in this process. But also it could be used for the rotation of crops to the benefit of wildlife populations.
Conservation grazing in practice
The use of conservation grazing is dependent on what type of ecosystemEcosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
, habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
, and plant community are desired to be maintained or restored. Grazing
Grazing
Grazing generally describes a type of feeding, in which a herbivore feeds on plants , and also on other multicellular autotrophs...
is a beneficial tool used to create a grass and small shrub dominated area. Tasker and Bradstock found that grazed areas returned a lower vegetation complexity score than ungrazed, however this was mainly because tree species and shrubs produce higher complexity scores than grasses – the grazed areas were composed primarily of bunch grasses and the ungrazed were dominated by shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
species. Certain areas that have been, historically, woody forest, may be chosen to be restored back to historical conditions, thus Tasker’s and Bradstock’s study would imply that wooded areas should remain ungrazed by livestock such as cattle.
Conservation practices such as grazing need to be monitored closely. If they are not, the practice can become overused and have an opposite effect than intended. Overgrazing may cause erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
, habitat destruction, soil compaction
Soil compaction
In Geotechnical engineering, soil compaction is the process in which a stress applied to a soil causes densification as air is displaced from the pores between the soil grains. When stress is applied that causes densification due to water being displaced from between the soil grains then...
, or reduced biodiversity (species richness
Species richness
Species richness is the number of different species in a given area. It is represented in equation form as S.Species richness is the fundamental unit in which to assess the homogeneity of an environment. Typically, species richness is used in conservation studies to determine the sensitivity of...
).
One issue of controversy with grazing is whether conservation grazing is in fact beneficial to a grassland
Grassland
Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...
community and what intensity of grazing management needs to be taken. Rambo and Faeth found that the use of vertebrates for grazing of an area would increase the species richness of plants by decreasing the abundance of dominant species
Dominant species
Dominant species may mean:*Dominant species , one of a small number of species which dominate in an ecological community*Dominant Species by Michael E. Marks*Dominant Species...
and increasing the richness of rarer species. The decrease in abundance may lead to a more open forest canopy and more room for other plant species to emerge.
Grazing restoration effect dependent on grazer species
Different grazing species have different effects. For example, elk and horses have a similar grazing frequency to cattle but tend to spread their zone of grazing to cover a greater area, producing a smaller effect on a given area than cattle would. Similarly, cattle have been found to be more useful in the restoration of pastures with low species richness, and sheep were found useful for the re-establishment of neglected fields. The type of area that needs to be restored or maintained will determine the species of grazer ideal for conservation grazing. Dumont et al. found in the use of varied breeds of steers that “traditional breeds appeared slightly less selective than commercial breeds”, but did not make a significant difference in biodiversity. In this particular study biodiversity was maintained by the same amount by both breed types.Effects on native and non-native plant species
Conservation grazing is a tool used for conserving biodiversity. However, one danger in grazing is the potential for invasive speciesInvasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
to be enhanced as well as the native biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
. A study by Loeser et al. showed that areas of high intensity grazing and grazer removal increased the biomass
Biomass
Biomass, as a renewable energy source, is biological material from living, or recently living organisms. As an energy source, biomass can either be used directly, or converted into other energy products such as biofuel....
of nonnative introduced species
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
. Both showed that an intermediate approach is the best method. The nonnatives did demonstrate that they were not as well adapted to the disturbances, such as drought
Drought
A drought is an extended period of months or years when a region notes a deficiency in its water supply. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region...
. This indicated that implementing controlled grazing methods would decrease the abundance of nonnatives in those plots that had not been properly managed.
Effects of grazing can also depend on the individual plant species and its response to grazing. Plants that are adapted to extensive grazing (such as that done by cattle) will respond quicker and more effectively to grazing than native species that have not had to cope with intense grazing pressure in the past. An experiment done by Kimball and Schiffman showed that grazing increased the cover of some native species but did not decrease the cover of nonnative species. The species diversity of the native plants was able to respond to the grazing and increase diversity. The community would become denser than originally with the increased biodiversity. (However, this may have been simply variance in plots due to the fact that the native and nonnative compositions were of different species between the grazed and ungrazed plots.)
Insects and butterflies
Degree of grazing has a significant effect on the species richnessSpecies richness
Species richness is the number of different species in a given area. It is represented in equation form as S.Species richness is the fundamental unit in which to assess the homogeneity of an environment. Typically, species richness is used in conservation studies to determine the sensitivity of...
and abundance of insects in grasslands. Land management in the form of grazing tends to decrease diversity with increased intensity. Kruess and Tscharntke attribute this difference to the increased height of grasses in the ungrazed areas. The study showed that the abundance and diversity of insects (such as butterfly adults, trap-nesting bees and wasps) were increased by increased grass height. However, other insects such as grasshoppers responded better to heterogeneity of the vegetation.
Vertebrates
Grazing can have varied effects on vertebrates. Kuhnert et al. observed that different bird species react in different ways to changes in grazing intensity. Grazing has also been thought to decrease the abundance of vertebrates, such as the Prairie DogPrairie dog
Prairie dogs are burrowing rodents native to the grasslands of North America. There are five different species of prairie dogs: black-tailed, white-tailed, Gunnison's, Utah and Mexican prairie dogs. They are a type of ground squirrel, found in the United States, Canada and Mexico...
and the Desert Tortoise
Desert Tortoise
The desert tortoise is a species of tortoise native to the Mojave desert and Sonoran desert of the southwestern United States and northwestern Mexico. They can be located in western Arizona, southeastern California, southern Nevada, and southwestern Utah. The species name agassizii is in honor of...
. However, Kazmaier et al. found that the effect of moderate grazing on the Texas Tortoise
Texas Tortoise
The Texas Tortoise , is one of four species of tortoise that are native to North America. Its range extends from southern Texas southward into the Mexican states of Coahuila, Nuevo León, and Tamaulipas...
did not show a significant difference when comparing grazed and ungrazed plots.
Rabbits have been widely discussed due to their influences on land composition. Bell and Watson found that rabbits show grazing preference for different plant species. This preference can alter the composition of a plant community. In some cases, if the preference is for a non-native, invasive plant, rabbit grazing may benefit the community by reducing non-native abundance and creating room for the native plant species to fill. When rabbits graze in moderation they can create a more complex ecosystem, by creating more variable environments that will allow for more predator-competitor relationships between the various organisms. However, besides the effect on wild vegetation, rabbits destroy crops, compete with other herbivores, and can result in extreme ecological damage. Competition can be direct or indirect. The rabbits may specifically eat the competitions target food or it may inhibit the growth of grasses that other species eat. For example, rabbit grazing in the Netherlands inhibits tall grasses from becoming dominant. This in turn enhances the suitability of the pasture for Brent Goose
Brent Goose
The Brant or Brent Goose, Branta bernicla, is a species of goose of the genus Branta. The Black Brant is an American subspecies. The specific descriptor bernicla is from the same source as "barnacle" in Barnacle Goose, which looks similar but is not a close relation.-Appearance:The Brant Goose is...
. However, they may benefit predators that do better in open areas, because the rabbits reduce the amount of vegetation making it easier for those predators to spot their prey.
Effect on ephemeral wetland ecosystems
EphemeralEphemeral
Ephemeral things are transitory, existing only briefly. Typically the term is used to describe objects found in nature, although it can describe a wide range of things....
wetlands degradation and loss of biodiversity had, at one point in time, been blamed on mismanaged grazing of both native and non-native ungulates and other grazers. A study done by Jaymee Marty of The Nature Conservancy
The Nature Conservancy
The Nature Conservancy is a US charitable environmental organization that works to preserve the plants, animals, and natural communities that represent the diversity of life on Earth by protecting the lands and waters they need to survive....
examined the effects on the vernal pools formed in California when grazers were removed. The results of the short study showed that areas where grazers were removed had a lower diversity of native grasses, invertebrates and vertebrates in the pools, with an increase in non-native grass abundance and distribution in the area. The study also demonstrated reduced reproduction success of individual species in the area, such as the Western Spadefoot Toad
Western Spadefoot Toad
Western Spadefoot or Western Spadefoot Toad is the common name of two different species of toads*Spea hammondii, found in North America*Pelobates cultripes, found in Europe...
and California Tiger Salamander
California Tiger Salamander
The California tiger salamander is a vulnerable amphibian native to Northern California. Previously considered to be a Tiger Salamander subspecies, the California tiger salamander was recently designated a separate species again...
. Marty argues that this decrease is due to ecosystems adapting to historical changes in grazers and the effects they have. In other words, the historic ecosystem, theoretically, would have responded positively to the removal of cattle grazing, however, the system has adapted to the European introduced species and require now may require them for maintained diversity. In another study performed by Pyke and Marty, measurements showed that on average, vernal ponds on grazed land pooled longer than ungrazed areas and soil was more resistant to water absorption in the grazed areas.
See also
- Epping ForestEpping ForestEpping Forest is an area of ancient woodland in south-east England, straddling the border between north-east Greater London and Essex. It is a former royal forest, and is managed by the City of London Corporation....
- New ForestNew ForestThe New Forest is an area of southern England which includes the largest remaining tracts of unenclosed pasture land, heathland and forest in the heavily-populated south east of England. It covers south-west Hampshire and extends into south-east Wiltshire....
- OostvaardersplassenOostvaardersplassenThe Oostvaardersplassen is a nature reserve in the Netherlands, covering about . Despite having developed recently it already has international importance as a European wetland....
External links
- Rent-a-Goat, video from WiredWired (magazine)Wired is a full-color monthly American magazine and on-line periodical, published since January 1993, that reports on how new and developing technology affects culture, the economy, and politics...