Beetles and spiders as indicators of forest recovery on Prince of Wales Island, Alaska

Forestry practices are one of the most significant human disturbances affecting forests today.  Commercial logging converts old growth stands into clear cuts that become even-aged forests.  Commercial logging occurred in the Tongass National Forest during the 1950s, creating 430,000 acres of young even-aged stands.  The Tongass-Wide Young-Growth Studies (TWYGS) program was designed to determine which thinning method of even-aged stands best increased understory vegetation and enhanced wood production.  Some of the TWYGS sites were set on Prince of Wales Island, Alaska where there was intensive logging.  I used beetles and spiders as indicators of recovery to old growth conditions to compare these thinning practices.  Twenty-four sites were chosen, including old growth, clear cuts and secondary growth with 6 replicates each and the treatments of thinned secondary growth with 14 ft., 16 ft. and 18 ft. spacing between trees left standing, with two replicates each.  For sampling at each site, 4 pairs of pitfall traps, 2 Lindgren funnels and 1 Berlese funnel were used with samples collected every two weeks.  Vegetation surveys at each site included tree height, Diameter at Breast Height (DBH), basal area, Leaf Area Index (LAI), and percent cover of herbaceous plants.  Species composition was summarized by using Shannon’s index and the Bray-Curtis dissimilarity index.  In addition, I used Multi-Dimensional Scaling (MDS) to assess the overall community structure of the different types of sites. Treatments that exhibit a species composition similar to that of old growth stands will be considered the furthest along to recovery.