Landscape Pattern, Ecological Processes
and Critical Thresholds

Monica G. Turner
Department of Zoology
University of Wisconsin

Ecological Thresholds Meeting
November 4-5, 2002



The development of landscape ecology has brought increasing attention to the causes and consequences of spatial heterogeneity at many scales. Critical thresholds in landscape pattern provide an example of a nonlinearity with important implications for understanding the relationship between patterns and processes and significant implications for land/resource management. A critical threshold refers to a condition beyond which there is an abrupt change in a quality, property or phenomenon. Threshold dynamics are particularly important because they often lead to ecological surprises: near a threshold, small changes often produce large and unexpected responses. Threshold dynamics may also define qualitatively different states of a system, which may aid explanation or prediction and will constrain extrapolation. Three examples of critical thresholds within the context of landscape patterns are presented: thresholds in habitat connectivity, scale of predictive relationships, and patch size. Population and ecosystem responses are used to illustrate each example. Implications for basic and applied research are discussed.