What is Biodiversity? (continued)

Certainly biodiversity can be appreciated on aesthetic grounds, i.e., variety in nature makes it a more beautiful and magical place, but the need for diversity is more basic than that.  Ecological simplification is reducing a complex web toward a simple chain.  A common ecological concept is that removing one link from a food chain destroys the entire chain.  This is true, but fortunately very few natural systems are simple chains; instead they are webs.  Webs are much more stable than a chain, because if one strand in the web breaks, the system can rely on other strands to keep the system strong. It is the difference between a corn field with acres of a single plant species and a prairie of dozens of vascular plant species.  Not only does the prairie support a much greater diversity of animal life, but it also is able to sustain itself through disease, inclement weather, insect attack, etc… much better than any monoculture would.  Ecological simplification can be caused by land use practices (monoculture agriculture, filling in wetlands, planting only one species of tree), urbanization and suburbanization (turning natural areas in concrete, buildings, and lawns), introduction of aggressive non-native species that push out a variety of native species (see purple loosestrife and zebra mussels), and pollution (herbicides, pesticides, chemicals, etc…) disrupting the natural cycles of a community.

According to Botkin and Keller (2000), factors that tend to increase biological diversity are 1) a physically diverse habitat, 2) moderate amounts of disturbance (e.g., occasional storm, flood, fire), 3) natural succession, and 4) evolution.  Factors that tend to decrease diversity include 1) environmental stress, 2) extreme environments (e.g., polar regions), 3) extreme disturbance, 4) introduction of exotic species, and 5) geographic isolation (a real or an ecological island shrunk to the point that the influx of new genetic material is unlikely). 

<<   -----  >>