First Sentence

"The expansion of human populations and their increasing consumption rate and access to technology have led to two general environmental concerns (NRC 1994; Vitousek et al. 1997): (1) the increasing human impact on the earth's environment and ecosystems through changes in the carbon pools of the biosphere, element cycling, and climate, and (2) changes in the earth's biota and communities, including species introductions and extinctions, and the fragmentation of natural communities through changes in land use."