Mohamed Omar
14-06-2009, 11:23 PM
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Grazing generally describes a type of predation in which an herbivore feeds on plants (such as grasses), and also on other multicellular autotrophs (such as algae). Grazing differs from true predation because the organism being eaten is not killed, and it differs from parasitism as the two organisms do not live together, nor is the grazer necessarily so limited in what it can eat (see generalist and specialist species).
Many small selective herbivores follow larger grazers, who skim off the highest, tough growth of plants exposing tender shoots. For terrestrial animals grazing is normally distinguished from browsing in that grazing is eating grass or other low vegetation, and browsing is eating woody twigs and leaves from trees and shrubs [1].
Grazing is important in agriculture, in which domestic livestock are used to convert grass and other forage into meat, milk and other products.
The word "graze" derives from the Old English (OE) grasian, "graze", itself related to OE graes, "grass".
http://f.zira3a.net/my-files/16366_11245010008.jpg (http://f.zira3a.net)
Grazing Systems
In the 19th century, grazing techniques were virtually non-existent. Pastures would be grazed for long periods of time, with no rest in between. This led to overgrazing and it was detrimental to the land, wildlife, and livestock producers. Today, ranchers have developed grazing systems to help improve the forage production for livestock, while still being beneficial to the land
Controlled vs. Continuous
Two major types of grazing management are controlled and continuous With continuous grazing, the livestock have free selection of forage, while with controlled grazing, the producer regulates forage availability and quality
Seasonal
Seasonal grazing incorporates “grazing animals on a particular area for only part of the year” This allows the land that is not being grazed to rest and allow for new forage to grow
Rotational
Rotational grazing “involves dividing the range into several pastures and then grazing each in sequence throughout the grazing period” Utilizing rotational grazing can improve livestock distribution while incorporating rest period for new forage
Rest Rotation
Rest rotation grazing "divides the range into at least four pastures. One pasture remains rested throughout the year and grazing is rotated amongst the residual pastures." This grazing system can be especially beneficial when using sensitive grass that requires time for rest and regrowth
Deferred Rotation
Deferred rotation “involves at least two pastures with one not grazed until after seed-set” By using deferred rotation, grasses can achieve maximum growth during the period when no grazing occurs
Patch Burn Grazing
Patch burn grazing consists of burning a portion of a pasture, while using intensive grazing on the other part throughout the year. This increases new growth and the cattle are attracted to the new grass following the fire
Riparian Area Grazing Management
Riparian area grazing is used more towards improving wildlife and their habitats. It utilizes fencing to keep livestock off ranges near streams or water areas until after wildlife or waterfowl periods, or limiting the amount of grazing to a short period of time
Ecological effects
number of ecological effects derive from grazing, and these may be either positive or negative. Negative effects of grazing (or more usually over-grazing) include increased soil erosion, adverse water quality impacts from increased runoff and loss of biodiversity. For example historical grazing, along with other land consversion, in Northern and Central California has reduced native chaparral and forest lands by approximately 70 percent. Ongoing grazing expansion {and land conversion} driven by human population growth in this region threatens the remaining integrity of California montane chaparral habitat in this region.
In some habitats, appropriate levels of grazing may be effective in restoring or maintaining native grass and herb diversity in rangeland that has been disturbed by overgrazing, lack of grazing (such as by the removal of wild grazing animals), or by other human disturbance. Conservation grazing is the use of domestic livestock to manage such habitats, often to replicate the ecological effects of the wild relatives of livestock, or those of other species now absent or extinct. For example, heathland in Europe requires grazing by cattle, sheep or other grazers to maintain its structure and diversity.
Much grazing land has resulted from a process of clearance or drainage of other habitats such as woodland or wetland
Benefits
Production
By utilizing grazing systems, livestock production has the potential to be maximized. “Approximately 85 percent of U.S. grazing lands are unsuitable for producing crops. Grazing animals on this land more than doubles the area that can be used to produce food. Cattle serve a valuable role in the ecosystem by converting the forages humans cannot consume into a nutrient-dense food”.Some could say ranchers themselves are conservationists. They work to use natural resources and often perform tests on their land to analyze soils, control weeds, and utilize smart grazing practices. Through this, they benefit themselves by using profitable land to maximize their livestock production in turn for a profit
Environmental
Although it’s often forgotten, grazing is very beneficial to the ecosystem. It is advantageous towards the soil and grasses, promoting nutrient dense soil and stimulating the growth of plant varieties. Through grazing, livestock encourages plant growth, consequently increasing forage production. Furthermore, the animal’s urine and feces "recycle nitrogen, phosphorus, potassium and other plant nutrients and return them to the soil".It also acts as rations for insects and organisms found within the soil. These organisms “aid in carbon sequestration and water filtration”. Nutrients and organisms, all of which are necessary for soil to be prosperous and capable for production.
Grazing also helps to promote the growth of native plants and grasses. Often, these indigenous plants aren’t able to compete with the surrounding plants that utilize the majority of water and nutrients. By livestock grazing, the non-native grasses are controlled and the native plants can redevelop. As well as using grazing to increase plant growth, the actual hoof action of the livestock also promotes growth. The trampling helps to imbed the seeds into the soil so that the plants and grasses can continue to germinate. Additionally, management in many parks makes use of grazing to help lower fire hazards by reducing the amount of potential fuel, such as large buildups of forage. When the land is not grazed, dead grasses accumulate. These dead grasses are often a large fire hazard in the summer months. On the other hand, grazing can also allow for "accumulation of litter (horizontal residue)" helping to eliminate soil erosion. Soil erosion is important to minimize because with the soil erosion comes a loss of nutrients and the topsoil. All of which are important in the regrowth of vegetation
Biodiversity
grasses that are stimulated through grazing provide a habitat for many species. When the land is left unattended or is not grazed, grasses will die with the seasons and accumulate as litter on the ground. For many birds, this is not attractive and they avoid making a nesting area of it. However, when the grass is grazed, the dead litter grass is reduced and allows for the birds to utilize it, while at the same time the livestock benefit.Just as importantly, it increases species richness. When grazing is not used, many of the same grasses grow, for example, brome and bluegrass, consequently creating a monoculture.
In North American tallgrass prairies, diversity and productivity are controlled to a large extent by nitrogen availability…Nitrogen availability in prairies was driven by interactions between frequency of fires and grazing by large herbivores…Spring fires enhance growth of certain grasses, and herbivores such as bison preferentially graze these grasses, keeping a system of checks and balances working properly, and allowing many plant species to flourish
Grazing generally describes a type of predation in which an herbivore feeds on plants (such as grasses), and also on other multicellular autotrophs (such as algae). Grazing differs from true predation because the organism being eaten is not killed, and it differs from parasitism as the two organisms do not live together, nor is the grazer necessarily so limited in what it can eat (see generalist and specialist species).
Many small selective herbivores follow larger grazers, who skim off the highest, tough growth of plants exposing tender shoots. For terrestrial animals grazing is normally distinguished from browsing in that grazing is eating grass or other low vegetation, and browsing is eating woody twigs and leaves from trees and shrubs [1].
Grazing is important in agriculture, in which domestic livestock are used to convert grass and other forage into meat, milk and other products.
The word "graze" derives from the Old English (OE) grasian, "graze", itself related to OE graes, "grass".
http://f.zira3a.net/my-files/16366_11245010008.jpg (http://f.zira3a.net)
Grazing Systems
In the 19th century, grazing techniques were virtually non-existent. Pastures would be grazed for long periods of time, with no rest in between. This led to overgrazing and it was detrimental to the land, wildlife, and livestock producers. Today, ranchers have developed grazing systems to help improve the forage production for livestock, while still being beneficial to the land
Controlled vs. Continuous
Two major types of grazing management are controlled and continuous With continuous grazing, the livestock have free selection of forage, while with controlled grazing, the producer regulates forage availability and quality
Seasonal
Seasonal grazing incorporates “grazing animals on a particular area for only part of the year” This allows the land that is not being grazed to rest and allow for new forage to grow
Rotational
Rotational grazing “involves dividing the range into several pastures and then grazing each in sequence throughout the grazing period” Utilizing rotational grazing can improve livestock distribution while incorporating rest period for new forage
Rest Rotation
Rest rotation grazing "divides the range into at least four pastures. One pasture remains rested throughout the year and grazing is rotated amongst the residual pastures." This grazing system can be especially beneficial when using sensitive grass that requires time for rest and regrowth
Deferred Rotation
Deferred rotation “involves at least two pastures with one not grazed until after seed-set” By using deferred rotation, grasses can achieve maximum growth during the period when no grazing occurs
Patch Burn Grazing
Patch burn grazing consists of burning a portion of a pasture, while using intensive grazing on the other part throughout the year. This increases new growth and the cattle are attracted to the new grass following the fire
Riparian Area Grazing Management
Riparian area grazing is used more towards improving wildlife and their habitats. It utilizes fencing to keep livestock off ranges near streams or water areas until after wildlife or waterfowl periods, or limiting the amount of grazing to a short period of time
Ecological effects
number of ecological effects derive from grazing, and these may be either positive or negative. Negative effects of grazing (or more usually over-grazing) include increased soil erosion, adverse water quality impacts from increased runoff and loss of biodiversity. For example historical grazing, along with other land consversion, in Northern and Central California has reduced native chaparral and forest lands by approximately 70 percent. Ongoing grazing expansion {and land conversion} driven by human population growth in this region threatens the remaining integrity of California montane chaparral habitat in this region.
In some habitats, appropriate levels of grazing may be effective in restoring or maintaining native grass and herb diversity in rangeland that has been disturbed by overgrazing, lack of grazing (such as by the removal of wild grazing animals), or by other human disturbance. Conservation grazing is the use of domestic livestock to manage such habitats, often to replicate the ecological effects of the wild relatives of livestock, or those of other species now absent or extinct. For example, heathland in Europe requires grazing by cattle, sheep or other grazers to maintain its structure and diversity.
Much grazing land has resulted from a process of clearance or drainage of other habitats such as woodland or wetland
Benefits
Production
By utilizing grazing systems, livestock production has the potential to be maximized. “Approximately 85 percent of U.S. grazing lands are unsuitable for producing crops. Grazing animals on this land more than doubles the area that can be used to produce food. Cattle serve a valuable role in the ecosystem by converting the forages humans cannot consume into a nutrient-dense food”.Some could say ranchers themselves are conservationists. They work to use natural resources and often perform tests on their land to analyze soils, control weeds, and utilize smart grazing practices. Through this, they benefit themselves by using profitable land to maximize their livestock production in turn for a profit
Environmental
Although it’s often forgotten, grazing is very beneficial to the ecosystem. It is advantageous towards the soil and grasses, promoting nutrient dense soil and stimulating the growth of plant varieties. Through grazing, livestock encourages plant growth, consequently increasing forage production. Furthermore, the animal’s urine and feces "recycle nitrogen, phosphorus, potassium and other plant nutrients and return them to the soil".It also acts as rations for insects and organisms found within the soil. These organisms “aid in carbon sequestration and water filtration”. Nutrients and organisms, all of which are necessary for soil to be prosperous and capable for production.
Grazing also helps to promote the growth of native plants and grasses. Often, these indigenous plants aren’t able to compete with the surrounding plants that utilize the majority of water and nutrients. By livestock grazing, the non-native grasses are controlled and the native plants can redevelop. As well as using grazing to increase plant growth, the actual hoof action of the livestock also promotes growth. The trampling helps to imbed the seeds into the soil so that the plants and grasses can continue to germinate. Additionally, management in many parks makes use of grazing to help lower fire hazards by reducing the amount of potential fuel, such as large buildups of forage. When the land is not grazed, dead grasses accumulate. These dead grasses are often a large fire hazard in the summer months. On the other hand, grazing can also allow for "accumulation of litter (horizontal residue)" helping to eliminate soil erosion. Soil erosion is important to minimize because with the soil erosion comes a loss of nutrients and the topsoil. All of which are important in the regrowth of vegetation
Biodiversity
grasses that are stimulated through grazing provide a habitat for many species. When the land is left unattended or is not grazed, grasses will die with the seasons and accumulate as litter on the ground. For many birds, this is not attractive and they avoid making a nesting area of it. However, when the grass is grazed, the dead litter grass is reduced and allows for the birds to utilize it, while at the same time the livestock benefit.Just as importantly, it increases species richness. When grazing is not used, many of the same grasses grow, for example, brome and bluegrass, consequently creating a monoculture.
In North American tallgrass prairies, diversity and productivity are controlled to a large extent by nitrogen availability…Nitrogen availability in prairies was driven by interactions between frequency of fires and grazing by large herbivores…Spring fires enhance growth of certain grasses, and herbivores such as bison preferentially graze these grasses, keeping a system of checks and balances working properly, and allowing many plant species to flourish