Patch dynamics and environmental heterogeneity in lotic ecosystems

We reviewed concepts of patch dynamics and environmental heterogeneity and their applications to the study of fluvial ecosystems, with emphasis on research published in J-NABS. We discuss several important papers synthesizing theories and findings on this topic and reports of descriptive and experimental research. A large body of research, much of it published in J-NABS, has demonstrated how spatial and temporal variation influences population, community, and ecosystem patterns and processes in fluvial ecosystems. Conceptual models of patch dynamics can be traced to 2 basic approaches: 1) the landscape ecology perspective and 2) the metacommunity perspective. The former focuses on how spatial patterns are created and affect ecological processes over variable scales of space and time, whereas the latter emphasizes the important influence of periodic disturbances, refugia, and dispersal in maintaining nonequilibrium communities within patch mosaics. The origin of the metacommunity Patch Dynamics Concept can be traced to G. Evelyn Hutchinson’s ideas about nonequilibrium communities, and a key contribution was Townsend’s (1989) J-NABS review of the Patch Dynamics Concept in stream community ecology. The study of fluvial ecosystem ecology from a patch-dynamics landscape perspective is well represented by empirical studies published in J-NABS, but some emerging topics remain little studied, including: 1) experiments designed to test predictions of the Patch Dynamics Concept of metacommunities vs alternative models; 2) empirical documentation of patch dynamics and their effects on ecological processes across longitudinal, lateral, and temporal gradients; 3) the influence of species’ life-history attributes on community dynamics in relation to habitat characteristics and aspects of disturbance; and 4) the manner in which landscape patterns, patch dynamics, and metacommunity dynamics affect foodweb patterns and processes.