broader range of information required for ecosystem
such as climate or physiography (Fig. 1b). The climate
management.
factor, particularly temperature and precipitation, ac-
An ecological land classification also requires that
counts for the largest amount of variation in ecosystem
ecosystem components be organized at various scales
structure and function globally (Walter 1979, Vitousek
(Wilken 1981, O'Neil et al. 1986, Klijn and Udo de
1994, Bailey 1998). Physiography, or broad-scale land-
Haes 1994, Bailey 1996) on the basis of recognizing
forms, with a characteristic geologic substrate, surface
that the state factors operate within a hierarchy of dif-
shape, and relief are the boundary conditions that con-
fering spatial and temporal scales (Allen and Starr 1982,
trol the spatial arrangement and rate of geomorphic
Delcourt and Delcourt 1988, Forman 1995). This hier-
processes and thus affect the material (characteristic
archical linkage reveals that smaller scale features, such
lithologies or soil texture) and energy flows, which in
as vegetation, are nested within larger scale components,
turn affect ecosystem development (Wahrhaftig 1965,
a. Ecotypes are local-scale ecosystems composed of various
elements that exist within large regional ecosystems, or
ecoregions.
b. Factors affecting ecosystem distribution occur over a range of
scales within a nested hierarchy.
Figure 1. Interaction of interrelated state factors that control struc-
ture and function of ecosystems.
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