Cross-boundary Subsidy - Introduction and Development of The Concept

Introduction and Development of The Concept

The concept of cross-boundary subsidies developed out of a merging of ideas from the studies of landscape ecology and food web ecology. The ideas from landscape ecology allow the study of population, community, and food web dynamics to incorporate spatial relationships between landscape elements into an understanding of such dynamics (Polis et al. 1997).

Janzen (1986) first defined cross-boundary subsidies as a process whereby organisms that disperse from one patch into another impact resident organisms by providing increased food resources or opportunities for reproduction, thus serving as a subsidy to the residents. By this definition, only the cross-boundary movement of organisms is considered, but broader definitions of cross-boundary subsidies can also include materials such as nutrients and detritus (i.e. Marburg et al. 2006, Facelli and Pickett 1991).

Cross-boundary subsidies are a subset of the more general process of spatial subsidies (see Polis et al. 1997). Cross-boundary subsidies acknowledge the presence and role of the boundary between different habitat patches in mediating flows of organisms and materials. In contrast, spatial subsidies require only that external inputs of materials and organisms originate from outside the patch of interest.