Diversity (Sep 2011)
Frogs, Fish and Forestry: An Integrated Watershed Network Paradigm Conserves Biodiversity and Ecological Services
Abstract
Successfully addressing the multitude of stresses influencing forest catchments, their native biota, and the vital ecological services they provide humanity will require adapting an integrated view that incorporates the full range of natural and anthropogenic disturbances acting on these landscapes and their embedded fluvial networks. The concepts of dendritic networks, disturbance domains, the stream continuum, and hydrologic connectivity can facilitate this integration. Managing catchments based on these combined concepts would better maintain all the components of watersheds and the interacting processes that comprise their ecological integrity. To examine these ideas, I review riparian protection regulations in the Pacific Northwest of the United States, regulations considered by many to be among the best available, and evaluate their ability to protect headwater amphibians. I present evidence for the inadequacy of these rules to maintain robust populations of these amphibians, and discuss the implications of these shortcomings for downstream-dwelling coho salmon. Emphasizing headwaters (1st to 3rd-order channels), I discuss disturbance regimes and how differences in their fluvial and geomorphic processes determine the structuring of channels, their internal environments, and the composition of the resident biota. I examine amphibian dependence on specific channel attributes, and discuss links between their abundances, altered attribute states, and natural and anthropogenic disturbances. Using these examples, I discuss the limitations of current protections to maintain key attributes necessary to support robust populations of headwater amphibians, and via hydrologic connectivity, many downstream organisms. I propose that the goal of maintaining whole catchment biodiversity and ecological services could be improved by managing watersheds based on integrating science-based network organizing concepts and evaluating and adjusting outcomes with a suite of responsive bio-indicators.
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