One of the most striking features of the earths biota
is its extraordinary diversity, estimated to include about
10 million different species. One of the most conspicuous
aspects of contemporary global change is the rapid decline
of this diversity in many ecosystems (Figure 1). The
decline is not limited to increased rates of species
extinction, but includes losses in genetic and functional
diversity across population, community, ecosystem,
landscape, and global scales (Figure 2). The term
biodiversity refers collectively to all these aspects of
biotic diversity. The wide-ranging decline in biodiversity
results largely from habitat modifications and destruction,
increased rates of invasions by deliberately or accidentally
introduced non-native species, over-exploitation and other
human-caused impacts.