What is Land Cover and What Causes It to Change?

Land cover refers to vegetation and other materials that cover the surface of the Earth. In many parts of the world, land cover is natural, occurring in the form of grasslands, forests, wetlands, and other undisturbed landscapes. Elsewhere, land cover is predominantly controlled by human activities. Croplands, managed pastures, and plantation forests predominate in many rural areas, while roadways, residences, and other structures cover the land surface of cities

Land cover can change because of natural forces. The change in climate that followed the retreat of glaciers at the end of the last Ice Age led to successive transformation of forests in much of the U.S. and Canada. More recently, changes in drainage systems, including increases and decreases in the levels of water tables, have produced often dramatic changes in vegetation patterns.

Land-cover change most frequently results from changes in the ways that humans use the land. One example is seen in the expansion of cities, where forests and fields have been replaced by houses, factories, shopping centers, parks, and their attendant roads and parking lots. Another form of human- induced land cover change is seen in the deforestation of tropical rainforests, where trees have been removed for a variety of reasons, including the extraction of timber, the establishment of pastures and crops, and the generation of energy. In other parts of the world, a major cause of deforestation has been the increased collection of fuelwood to be used by rapidly growing populations for heating and cooking.

Just as human land uses may have profound impacts on land cover, human activities often lead to significant changes in marine ecosystems and in the productivity of fisheries, forests, soils, and other natural resources. Land uses influence the flow of water, nutrients, and sediments in coastal areas, thereby directly linking human populations with the nature and quality of marine ecosystems.


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Last updated 04/10/96