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Understory plant development in artificial canopy gaps in an 81-year-old forest stand on Chichagof Island, southeast AlaskaAuthor(s): Scott Harris; Jeffrey Barnard
Source: Res. Pap. PNW-RP-609. Portland, OR. U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 26 p.
Publication Series: Research Paper (RP)
Station: Pacific Northwest Research Station
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DescriptionThis study assesses the understory plant response and associated effects on forage resources available to Sitka black-tailed deer (Odocoileus hemionus sitkensis), to the creation of artificial canopy gaps in a young-growth forest stand in the coastal temperate rain forest of southeast Alaska. The forest stand was approximately 58 years old when gaps were created and approximately 81 years old when the most recent set of data was collected in 2013. Plant canopy cover estimates were collected five times over the 23-year period following the creation of nine artificial canopy gaps. We estimated the biomass of individual plant species and plant groups in the gaps and adjacent untreated forest using canopy cover to biomass regression equations to convert the data into estimates of kilograms of plant material per hectare. We estimated “deer days” per hectare for several summer and winter scenarios, in the gaps and untreated forest, by using the Forage Resource Evaluation System for Habitat (FRESH) deer model. Results were analyzed with a Wilcoxian signed rank test (P<0.05). Results indicated that plant biomass and deer days per hectare were significantly higher in the gaps than the adjacent untreated forest at 23 years following creation of the gaps, increasing over the 23 years with no apparent peak. Compared to understory plant response for three thinning studies from southeast Alaska, results from this study indicate that deer days per hectare for the summer scenarios were greater for the thinning treatments, but lower for the winter scenario where low-lying forbs would likely be buried by snow. However, data from the thinning studies are available for only a few years following the treatments, so the comparisons are not precise. Although the results from our gap study should not be considered representative for southeast Alaska because they are from only one stand, they do suggest that creating artificial canopy gaps in 58-year-old younggrowth stands is a viable option for increasing forage resources for deer.
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CitationHarris, S.H,; Barnard, J.C. 2017. Understory plant development in artificial canopy gaps in an 81-year-old forest stand on Chichagof Island, southeast Alaska. Res. Pap. PNW-RP-609. Portland, OR. U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 26 p.
KeywordsSoutheast Alaska, Sitka black-tailed deer, canopy gaps, forest ecology, FRESH deer.
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