Silviculture alters the genetic structure of an eastern hemlock forest in Maine, USA

• Published in: Canadian journal of forest research Vol. 35; no. 1; pp. 143 - 150
• Main Authors: Hawley, G.J, Schaberg, P.G, DeHayes, D.H, Brissette, J.C
• Format: Journal Article
• Language: English
• Published: Ottawa, Canada NRC Research Press 2005; National Research Council of Canada; Canadian Science Publishing NRC Research Press
• Subjects: Agronomy. Soil science and plant productions; alleles; Anthropogenic factors; Biological and medical sciences; Classical and quantitative genetics. Population genetics. Molecular genetics; Coniferous trees; cutting; Environmental changes; Evergreen trees; Forest management. Stand types and stand dynamics. Silvicultural treatments. Tending of stands. Natural regeneration; forest stands; forest thinning; forest trees; Forestry; Forests; Fundamental and applied biological sciences. Psychology; gene frequency; Generalities. Genetics. Plant material; Genetic effects; genetic resources; Genetic structure; genetic variation; Genetics and breeding of economic plants; Genetics of eukaryotes. Biological and molecular evolution; logging; phenotype; Pine trees; Population genetics; Population genetics, reproduction patterns; Pteridophyta, spermatophyta; rare alleles; Seed orchards; selection criteria; selective harvesting; silvicultural practices; silvicultural selection; Silviculture; stand density; stand management; Stand types and stand dynamics. Silvicultural treatments. Tending of stands. Natural regeneration; Tsuga canadensis; Vegetals; United States; Maine; North America; America; United States > US; Silviculture; Selection effect; Population structure; Ecology; Genetic diversity; Selection cutting; Population genetics; Tsuga canadensis; Softwood forest tree; Forestry; Gymnospermae; Coniferales; Spermatophyta; Anthropogenic factor; Coniferous forest
• ISSN: 0045-5067; 1208-6037
• DOI: 10.1139/x04-148

We evaluated the influence of long-term silvicultural selection on the genetic structure of an eastern hemlock (Tsuga canadensis (L.) Carr.) forest at the Penobscot Experimental Forest, in Maine, USA. Plots in this forest received one of the following three treatments: (1) selection cuts in which small and poorly formed trees were preferentially removed in 1957 and 1977; (2) diameter-limit cuts in which trees at least 24 cm in diameter were removed in 1952, 1973, and 1994; or (3) no harvesting (an unmanaged control). Because of an association between the occurrence of rare alleles and tree phenotypes, phenotypically based tree removals were associated with a shift in allelic frequency. Where smaller trees with inferior phenotypes were preferentially removed (selection cut), the number of rare alleles and estimates of future genetic potential were lower than in the control group. Because of the theoretical long-term evolutionary benefit of unique gene forms, the loss of rare alleles could diminish the potential of populations to adapt to and survive ongoing environmental change. In contrast, alleles that were rare in the control group existed at a higher frequency in the diameter-limit cut. However, productivity was low in this stand, where the frequency of characteristically rare alleles was artificially amplified.