ESTIMATING WILDLIFE HABITAT TRENDS ON AGRICULTURAL ECOSYSTEMS IN THE UNITED STATES

摘要

The kind, amount, and distribution of life supporting elements on the landscape collectively determine the quality of habitat useful to wildlife. Each species has unique requirements with regard to these various elements. Our knowledge of these requirements for most species is very limited while for a few species our understanding of their habitat needs is better. Species response to management of habitats exhibits great variability over scales of both time and space. While our ability to measure ecological pattern continues to improve there is much to be learned about ecological processes and functions. Although scientists continue to make models of ecological systems there remains a substantial amount of unexplained variance in the explanatory power of those models. Habitat management is therefore a combination of both science and art. Aldo Leopold (1966: p. 177-178) provided an interesting description: "There is much confusion between land and country. Land is the place where corn, gullies, andmortgages grow. Country is the personality of the land, the collective harmony of its soil, life, and weather.....Poor land may be rich country and vice versa. Only economists mistake physical opulence for riches. Country may be rich despite a conspicuous poverty of physical endowment, and its quality may not be obvious at first glance, nor at all times.... It [wildlife] often represents the difference between rich country and mere land," All land can be considered habitat, but its quality varies from extreme poverty to abundance.