Decisions will be made, directly or indirectly, as to how much and what kind of nature survives. Conservation pressures in the next century will come from a variety of sources. Habitat loss and degradation are the most important causes of wildlife decline, but overharvesting and poaching, trade in wild animal products, introduction of exotic species, pollution from pesticides and herbicides, and other causes also take a significant toll. Global warming or climate change could exacerbate the loss and degradation of biodiversity by increasing the rate of species extinction, changing population sizes and species distributions, modifying the composition of habitats and ecosystems, and altering their geographic extent. Essentially the problem involves proliferating human populations and associated land conversion which is powerfully changing the form and shape of the landscape.
People now constitute a pressure on the global environment that is evident everywhere.
This results in insufficient habitat for many species or situations in which habitats are isolated in separate pieces too small or too unstable to sustain viable populations of species and thus biological diversity. The theory of biogeography reveals that species richness is a function of land area. All environmental variables being equal, the greater the area, the more species it supports. Thus, as habitats are fragmented and isolated into small islands, they lose the capacity to support wildlife diversity. Texas has a great treasure in its mammalian fauna which provides our citizens with important recreational, commercial, aesthetic, and scientific values.