Environmental Engineering Reference
In-Depth Information
When vegetation on rangelands is over-consumed, it hinders plant regrowth. If the plants that are being eaten
are not being replaced over time, the land becomes degraded and unusable. Consequences of overgrazing in-
clude the following:
• Soil erosion
• Soil compaction
• Desertification
• Proliferation of invasive species
• Reduction in biodiversity and native vegetation
• Economic loss to those who depend on the land, such as ranchers
When excessive vegetation is removed from the soil, the land is exposed to wind and water. Once soil starts to
erode, it is more difficult for plant cover to regrow. The vegetation that does get a toehold in degraded range-
land consists mainly of invasive, weed-type plants, which livestock do not eat. The livestock also compact the
soils with their weight and hooves; over time, the soil can become compacted enough that it is more difficult
for water to seep through, blocking air from filling pore spaces, which roots need to grow. Once the conse-
quences of overgrazing become visible, the cycle is hard to break, and each step creates more degradation of
the land.
This cycle of degradation creating more degradation is called a
positive feedback loop,
in which, once the sys-
tem starts moving in a direction, it accelerates in that direction unless an intervention stops the progression.
This ultimately drives a system to an extreme. In this case, the extreme is degraded, unusable land.
Deforestation
Not all livestock is grazed on natural grassland. In some cases, forests are destroyed so local people can raise
cattle and other livestock on the cleared land. The methods used to clear the land include slash and burn, in
which entire sections of forest are cut down and burned. Sometimes grasses are then planted for livestock. In
some countries, such as Brazil, the leading cause of deforestation is cattle ranching. For decades, governments,
activists, businesses, and citizens have discussed deforestation due to its rapid rate of destruction and devastat-
ing effects such as biodiversity loss and ecosystem alteration. Forests, including rain forests, are cleared not
solely for livestock use but also for crop production, timber, land rights, and tax incentives.
Luckily, people are increasingly learning the consequences of deforestation, so new and sustainable methods
are being introduced and implemented in many places with the hope of saving natural forests and regenerating
degraded land, while also continuing to raise livestock.
Desertification
The loss of vegetation and available water can lead to land degradation and, ultimately, desertification. Over-
grazing is a major contributor to desertification, more so even than crop production. Contrary to popular opin-
ion, land does not move toward desertification from drought only. Drought can exacerbate the problem, but
overuse, deforestation, and climate change are the catalysts that create an area of land prone to desertification.
Erosion born of deforestation and excessive use degrade the land, making it more difficult for the land to re-
cover. Eventually, the land loses its ability to recuperate, especially in circumstances that are exacerbated by
drought. Under these conditions, the land can become a desert. This is more common in arid or semiarid areas
that do not receive large amounts of water on an annual basis. However, due to the large-scale deforestation of
rain forests, even these water-rich, tropical regions have seen the desertification of the land that was once
