Bootstrapping in EcosystemsInternal interactions largely determine productivity and stability in biological systems with strong positive feedback

ositive feedback is being increasingly recognized as an important component of tcosystem dynamics (DeAngelis et al. 1986, Gutierrez and Fey 1980, Pastor and Post 1988). Within the constraints of resource supply or other environmental factors, the biological system characterized by strong positive feedback among its components is in many respects self-generating-its productivity and stability determined largely through its internal interactions. "The idea of a system. . . generating [itself] in a self-consistent loop of explanation is reminiscent of the story of the boy who fell into a bog and hauled himself out by pulling on his own bootstraps, so. . . such modes of explanation [are called] 'bootstrapping' " (Davies 1983). A bootstrapping view, neither reductionist nor holistic in its basic orientation, can yield useful insights into ecosystem processes, particularly as they relate to stability and resilience. Systems characterized by strong, positive interactions among their components can be complex, productive, and quite stable under conditions to which they are adapted, but when key linkages are disrupted they are fragile and subject to threshold changes (DeAngelis et al. 1986). In this article we review recent Stable against normal disturbances, ecosystems based on close, mutual interactions may be quite vulnerable to foreign disturbances