EFFECTS OF EXPERIMENTAL FOREST MANAGEMENT ON AVIAN COMMUNITIES IN THE MISSOURI OZARKS

In recent decades, concern for migratory birds has stimulated research assessing the relationships between forest management and bird populations. The Missouri Ozark Forest Ecosystem Project (MOFEP) is a long-term, landscape-scale experiment designed to examine the effects of even-aged (i.e. clearcutting), uneven-aged (i.e. selection cutting), and no harvest forest management on ecosystem level processes. The management systems were randomly assigned to three sites each (mean area = 400 ha) under a 100-year rotation with a 15-year re-entry period. In the first chapter, we used non-metric multidimensional scaling and generalized linear mixed models to investigate the effects of silvicultural treatment and year-since-harvest on bird communities from 1991 to 2014 before and after two harvests (1996 and 2011). Bird communities diverged among treatments immediately post-harvest, but the differences in community composition and structure began to diminish by 8 years post-harvest. Species richness was higher in treated stands compared to no-harvest controls. Both species richness and diversity showed a linear decrease with year-since-harvest. Our findings demonstrate that even-aged and uneven-aged forest management can affect the bird community composition and structure within 3 years post-harvest, but differences may not be apparent by 12 years post-harvest. We recommend using a variety of silvicultural methods to provide the diversity of habitats needed for the conservation of diverse forest bird communities. In the second chapter, we used six years (three years before and after harvest) of concurrent point count and spot mapping data from the nine MOFEP sites to assess the ability of 50 m fixed-radius point counts to estimate bird abundance and management effects for 11 focal species. Additionally, we used species richness estimates to examine how similar the two survey methods are for community-level comparisons. Point count densities were generally correlated with spot map densities, but the strength of the relationship varied among species. Point counts also showed similar treatment effects as spot mapping, but the confidence intervals were much wider in point counts. The species richness estimates were only weakly correlated between the two surveying methods. Our results show that 50 m fixed-radius point counts reflect general population trends for the 11 species examined. Therefore, if broad-scale trends are adequate, point counts provide reasonable proxies for the more labor-intensive spot mapping