Abstract
Environmental gradients are a powerful and largely overlooked research tool. They exist only because of heterogeneity. The objective of this chapter is to provide an overview of techniques for using environmental gradients to explore heterogeneous systems. The chapter begins by noting that any tool is helpful only if it is used with a well-defined goal. The goal of “assembly rules” and “response rules” for communities is suggested and briefly described. Because not all habitats have obvious gradients, techniques for finding gradients where they are not obvious are then introduced. Eight guidelines for using gradients as research tools are explored. These guidelines deal with the following topics: (1) choosing gradients to maximize generality; (2) selecting independent variables; (3) selecting dependent variables and the value of screening to create “trait matrices”; (4) importance of inferential statistics for detecting patterns; (5) incorporating experiments into natural gradients; (6) merits of locating two orthogonal gradients; (7) making gradients if they cannot be found; and (8) considerations of scale. The chapter concludes by discussing centrifugal organization, a model of community organization at the landscape scale that is built around species’ responses to gradients.
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Keddy, P.A. (1991). Working with Heterogeneity: An Operator’s Guide to Environmental Gradients. In: Kolasa, J., Pickett, S.T.A. (eds) Ecological Heterogeneity. Ecological Studies, vol 86. Springer, New York, NY. https://doi.org/10.1007/978-1-4612-3062-5_10
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