- Hartley, Mitschka John
University of Maine Graduate School
I investigated effects of small-gap timber harvests on bird communities at nine sites (10 ha each) within the Penobscot Experimental Forest (PEF), grouped into three replicated "blocks" (three sites each). Blocks were randomly treated with three treatments: 70% harvest, 20% harvest, and no harvest (i.e., control). I examined how treatments affected breeding songbird abundance, richness, and site-fidelity over four consecutive summers, including 1-3 years before and after each site was harvested. Ability to detect treatment effects was limited by the small number of replicates, but power analyses indicated that given the experimental design and observed variability, there was a high (>80%) probability to detect 20%-30% differences in overall abundance among treatment groups. There was no evidence that treatments caused changes of this magnitude, or affected densities of individual species, avian richness, or which species were most abundant before versus after treatment. Annual variations in densities were much stronger than differences between treatment groups.