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The Ecological Issues for Temperate Grasslands

About 25 percent of Earth's vegetation-supporting land surface consists of temperate grasslands, a biome or type of large ecosystem that includes the South African veld, South American pampas, North American prairies and Eurasian steppes. Grasses and small shrubs, with few if any trees, characterize these ecosystems. Temperate grasslands experience cold winters, hot summers, and low to medium annual rainfall. Because of their desirability to farmers, temperate grasslands have long suffered multiple, interconnected ecological threats.

  1. Habitat Conversion

    • Habitat conversion is a human-caused change in land quality. By 1950, fully 70 percent of native temperate grasslands worldwide had undergone habitat conversion, and another 15.4 percent had by 1990. Expansion of urban and suburban areas and industrial-scale agriculture especially have resulted in soil depletion, contamination, and erosion. These forces have fragmented natural habitats into pieces too small to readily sustain native species.

    Overgrazing

    • Temperate grasslands are particularly vulnerable to habitat conversion through overgrazing. In their natural state, temperate grasslands support grazing by large, roaming populations of wild herbivores, such as the bison of the U.S. and Canadian prairies. Overgrazing by domesticated animals like sheep and cattle prevents the native vegetation from recovering and often turns the land into desert. Because of overgrazing, almost one-third of the Patagonian grasslands in Argentina and Chile has undergone severe desertification.

    Biodiversity Loss

    • While teeming with life, temperate grasslands often have fewer total numbers of native species than other biomes covering similarly large geographic areas. Thus they are more sensitive to biodiversity loss. For example, the mass slaughter of bison on the Great Plains during the 19th century caused extinctions and severe population declines among numerous, interconnected plant and animal species, including prairie dogs and birds. Especially when already stressed through human activity, temperate grasslands are prone to invasive or exotic species. The most dramatic example is the devastation wrought by the introduction of European rabbits into Australia's grasslands.

    Global Warming

    • Global warming stresses and will continue to stress all of Earth's biomes. Temperate grasslands are projected to become hotter and more arid. These developments will change the distributions of native species and make farming more difficult. However, according to the Food and Agricultural Organization of the United Nations, well-managed grasslands can mitigate greenhouse gas pollution.

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