Dissertation Research: Local Controls of Landscape Abundance Patterns of a Stream Salamander.

Dartmouth College, Hanover NH

Investigators

Abstract

0105091 Bolger This research investigates local and landscape-scale controls on the abundance of the spring salamander, Gyrinophilus porphyriticus (Plethodontidae), in headwater streams throughout the northeastern United States. Spring salamander abundance is negatively related to (1) post-timber harvest accumulation of sediment in streams, (2) the presence of predatory brook trout, and (3) distance to other streams which are potential immigrant sources. Experiments exploring the combined effects of sediment level and brook trout on spring salamander survival are proposed. These experiments will address the hypothesis that post-harvest sediment input reduces the survival of larval spring salamanders in streams occupied by brook trout by reducing the availability of refuges among the rocks of the streambed. Species abundance is controlled by factors acting both locally and at the landscape-scale. Local controls include within-population reproduction and survival rates. Landscape-scale controls are a function of dispersal rates among populations. Landscape-scale controls have been shown to be critical to species persistence in natural systems affected by human activities, but are poorly understood in stream systems. These experiments will elucidate how habitat disturbance affects species interactions in headwater streams and will permit the assessment of the mitigating influence of among-stream dispersal. This analysis will expand understanding of the basic ecology of stream species, and significantly improve the effectiveness of recovery strategies for these species following timber harvest.