Critical natural processes, including the life cycles of living things and evolution itself, depend on the maintenance of large intact areas, especially forested areas and other wildlands. To function effectively, these areas must remain relatively undisturbed by human activity. Breakdowns in the processes of nature are most noticeable in the loss of species we are experiencing, and in the resulting loss of biodiversity, which fuels the engine of evolution. We interfere with evolutionary processes at considerable risk to the natural world and to our own survival. The further costs of loss of species diversity are wide ranging, and still being counted.
Deforestation hinders regeneration and growth of non-tree plant life.
Soil loss where forests have been cleared can be staggering, as a result both of more rapid erosion and the loss of the forest's capacity to generate soil and sustain non-tree plants. Sometimes the impact of our interference with the natural processes protected by forests is very direct. The role of forests in meeting the needs of people for wood and wood products now dominates over all others. The driving force behind the loss of forest cover is the demand for wood to meet humankind's need for shelter, fuel wood, paper, and other wood products. Vast sectors of human activity, home-building for example, depend on wood and wood products.