Wanderlust World Wanderlust World Before the encroachments of civilization made their mark on the natural grassland habitats of North America, wildfire started by lightning strikes was a critical factor in maintaining healthy grasslands. Fire quickly reduces the grass to ash, releasing the nitrogen, phosphorus, magnesium and potassium. Subsequent rain or snowmelt drives the nutrients into the soil. Fires in grasslands still occur naturally, but often land managers now use controlled burns to mimic nature and to reduce the unpredictability of wildfire.
The grassland ecosystems rely on plant decomposition to enrich the soil. Most of the grasslands in the U.S. experience cold winters during which the plants freeze and the annual grasses are killed. The snow cover in winter provides insulation for the insects and small animals that live in the grasslands, making it possible for them to survive and feed on the decaying plants. The waste products of the life forms enrich the soil. Common small animals of the grasslands are mice, rabbits and snakes. Birds include quail, sparrows, meadowlarks, hawks and owls. Earthworms, leafhoppers, flies, ticks and grasshoppers all inhabit grasslands.
Animals native to the grassland prairies of North America include buffalo, coyote, deer and foxes. Coyotes and foxes eat both plant and animals, while buffalo and deer eat vegetation exclusively. The digestive processes of these animals create waste products that enrich the soil. As the animals eat the grasses, the roots of the plants regenerate new leaves, keeping the plant's growth cycle active. Introduced species such as cattle and sheep impact the native grassland biome by their grazing habits. While cattle chew the grasses down to the plant's crown, sheep pull the whole plant out of the ground, loosening and aerating the soil as well as allowing other plant species to enter the biome and thrive.
Natural grasslands support plant diversity, which helps them to fend off devastating invasions of insects, plant viruses and soil-borne diseases. Plant diversity creates a symbiotic process for both plant and animal life. Plants and animals can develop natural immunities over time, assuring the survival of a species. Milkweed grows in grasslands, and its white sap is toxic to many animals and insects. The monarch butterfly developed a resistance to the toxins in the sap, so it is one of the few predators that milkweed has. Areas undisturbed by farming near abandoned railroad tracks and old cemeteries serve as reservoirs for native plants and seeds that can be used to restore grassland biomes to a natural state.