PNW 98 Session - Full Abstracts

Full Abstract

CHRIS THOMS (1)
Charlotte Corkran (2)

(1) Corps of Engineers, Portland
(2) Northwest Ecological Research Institute

Characterizing and Integrating Useable Habitat Components in Successful Pond Breeding Amphibian Sites

Mitigation has not attempted to increase useable habitat for common amphibians of the Pacific Slope in Oregon and Washington. Observations of natural systems that support pond habitats and that were successfully used by amphibians, were made during a 6-year period on sites west of the Cascades. A system was developed to describe structural components within these aquautic habitats that had been successfully used for breeding and nursery sites by common amphibians (long-toed salamanders, northwestern salamanders, red-legged frogs, tree frogs and bull frogs). These components can be included into (or excluded from) wetland mitigation plans. Based on observations it was concluded that both 1)an understanding of natural systems that support pond habitats is necessary for choosing an appropriate mitigation site and 2)including structural components into mitigation plans can be described. There are several natural systems by which ponds are produced on the Pacific Slope, they are: 1)damming of running water by beaver or accumulation of debris, 2)seeping from ground water or springs and corresponding restriction of water movement, 3)slumping and development of sag ponds, 4)saturating and ponding of water due to incipent drainage patterns and 4)compacting of glacial tills by erratics, ice or other. An important aspect of these settings in the Pacific Northwest is that all of these aquatic systems have water moving through them for most of the winter, spring, and early summer. By late summer and fall, water only moves into these systems and often does not visibly move out of them. By fall and early winter, water is not visibly moving into or out of these settings. Within these habitats there have been observed three zones that support structural components, these are the substrate, the submersed zone and the emergent zone. Selection of an appropriate site that compliments a natural setting and the inclusion of several components within these three zones of the aquatic habitat my increase success in establishing amphibian habitat through mitigation.

I know this late but maybe you could still include it in your sessions. also This was very difficult to type and check for typos because there was only two long lines indicated. did I do something wrong? Thanks