Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms which previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of harvesting natural resources for industry production and urbanization. Clearing habitats for agriculture is the principal cause of habitat destruction. Other important causes of habitat destruction include mining, logging, trawling and urban sprawl. Habitat destruction is currently ranked as the most important cause of species extinction worldwide. It is a process of environmental change important in evolution and conservation biology. Additional causes include habitat fragmentation, geological processes, climate change, invasive species, ecosystem nutrient change and human activities mentioned below.
(From Wikipedia, May 10th, 2010)