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Spatial Scale & Hierarchy

Image: Spatial Scale & Hierarchy.Individual patches are influenced by interactions among freshwater, terrestrial, and human landscapes that occur at multiple spatial and temporal scales and that are hierarchically structured. Understanding these spatial hierarchies is a critical aspect of landscape limnology because (a) the characteristics of individual freshwater ecosystems are constrained by processes at higher spatial scales (Frissell et al. 1986, Tonn 1990, Poff 1997); (b) the degree of homogeneity among freshwater ecosystems can change in relation to the scale of observation; and (c) management and policy influencing a freshwater ecosystem are set at multiple spatial scales, from local to national levels.

For example, at the broadest spatial scale, biomes are shaped by climate, geology and landform, which act as constraints on the range of potential characteristics of observed within them. At the ecoregion scale, additional constraints related to finer scale spatial heterogeneity in features such as geology, soils, and landform are imposed, further limiting limnological expression. Lake characteristics are further defined by position within a hydrologic flowpath, which determines the strength and pattern of freshwater connections. Finally, individual lake characteristics (such as morphometry or the spatial arrangement of within lake habitat types) act within all the above constraints.