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The forested riparian area along many central Appalachian streams contains large volumes of harvestable timber. Best management practices (BMP) and streamside management zones (SMZ) have been developed to minimize the impacts of riparian timber harvest. Large woody debris (LWD) is an important component of forested streams and its role in chemical, biological, and physical processes in streams is complex. The extraction of timber within the streamside management zone reduces the amount of material available for aquatic structure. Three-250 m study reaches were established on eight Appalachian headwater streams. Four of the streams were assigned the treatment of having a 50% basal area removal of SMZ timber and four were assigned a 90% basal area removal of SMZ timber. The down and up sections of each stream were then randomly assigned to be either basal area removal (removal) treatment or basal area removal plus instream LWD addition (removal + LWD) treatment, with reference sections located upstream of the treatment sections. Pool habitat features changed substantially in all three sections, with variation between postharvest study years. However, pool area did not increase after the addition of LWD. Post-harvest stream temperature exhibited a constant pattern of increased warming as water moved downstream through the harvest zones. Mean maximum daily temperature downstream of timber harvest in 90% removal streams was an average of 3.1 o C warmer than above harvest sections, and mean daily temperature was 1.1 o C warmer. The 50% removal streams did not exhibit the large increases in stream warming seen in the 90% removal streams. Seasonal population estimates of brook trout were conducted in 2005 (pre-treatment) 2007 and 2008 (post-treatment). Brook trout populations fluctuated over time, but did not show a consistent increase following treatment. Mean total length of YOY brook trout did vary across some streams and sections but was not significant among treatments. The condition (Wr) of age 1+ brook trout (> 120 mm) did not differ between treatment and reference sections in 50% or 90% streams. Overall percent retention of resident fish differed significantly between sections. Percent immigration was high in all sections (60-71%) suggesting high rates of movement. Consumption estimates by origin of prey varied significantly within sections over the course of the study. Brook trout consumed a greater proportion of terrestrial invertebrates in reference sections than in timber removal sections during the study. Increased timber harvest intensity resulted in decreased consumption of terrestrial invertebrates by brook trout. Terrestrial invertebrates represent a greater proportion of the abundance, biomass and energy for brook trout in reference sites and may be greatly reduced in timbered areas. Brook trout in removal and reference sections exploited particular prey taxa at significantly different rates. The results of our study show that it is necessary to assess trends in habitat changes, and brook trout populations over several years as there are several unknowns associated with the possible response to varying basal area removal. In addition, our study suggests that there could be changes in brook trout diet in the removal sections and a potential shift in the feeding habits of brook trout, and a reduction of terrestrial invertebrate availability to brook trout may result in decreased growth of Appalachian brook trout in these sections.

Brook trout response to canopy and large woody debris manipulations in Appalachian streams