Aquatic-terrestrial linkages in Appalachian streams: Influence of riparian inputs on stream habitat, brook trout populations, and trophic dynamics.

Riparian zones play a major role in the structure and function of headwater stream ecosystems. Inputs of leaf litter from riparian zones are the primary energy source for secondary production in these streams and inputs of large woody debris (LWD) help shape stream habitat. Riparian zones of Appalachian streams were degraded by past timber harvest activities. Streamside management zones (SMZs) now protect the riparian zone by limiting timber harvest activities near streams. The objective of this study was to examine aquatic-terrestrial linkages and how habitat and food resources influence brook trout ( Salvelinus fontinalis) populations in Appalachian streams. LWD was experimentally added to eight streams in the Middle Fork River watershed, Randolph Co., WV to determine if stream habitat and prey availability could be enhanced. Stream habitat was assessed and brook trout populations were monitored for one year prior to, and three years following habitat manipulations. Invertebrate drift and brook trout diets were collected to determine the effects of LWD additions on trophic dynamics and to assess the importance of terrestrial invertebrate prey to brook trout energetics. LWD additions had little effect on stream habitat by three years post-manipulation. Brook trout populations fluctuated over time, but did not show a consistent increase. Although, the number of locations where leaf litter was stored increased, invertebrate drift did not increase following the addition of LWD. Likewise, prey consumption by brook trout was not influenced by the LWD additions, but diet composition showed a shift with the proportion of the diet comprised of the shredder functional feeding group increasing by two years post-habitat manipulation. Terrestrial invertebrates comprised a large portion of the yearly consumed energy by brook trout. The results of this study illustrate the important linkage between terrestrial and aquatic systems in the trophic dynamics of headwater streams. However, the duration of the study was likely not long enough to detect significant changes in stream habitat and brook trout populations due to LWD additions. The benefits of these habitat manipulations may not be realized for several more years. These initial results may help guide resource managers in future stream restoration efforts