RNGR.net is sponsored by the USDA Forest Service and Southern Regional Extension Forestry and is a colloborative effort between these two agencies.

U.S. Department of Agriculture USDA Forest Service Southern Regional Extension Forestry Southern Regional Extension Forestry

Genetic diversity in conifer stands: Evaluation, maintenance and improvement

Maintaining an "optimum" level of genetic diversity is often espoused as a reason to avoid plantation forestry as it is commonly practiced in the Southeast. Natural regeneration with selective harvesting is expected to yield a more diverse population than planting with seed orchard based seedlings and clearcutting. Whether or not this philosophy is valid is dependent upon the measure of diversity, the level of diversity in the originating population, seed dispersal patterns, reproductive phenology, natural selection, genetic drift, etc. Small, patchy highly related groups of trees are possible in naturally regenerated forests and successive generations may become inbred or extremely narrow in their genetic base. Effective population size, coancestry levels, and heterozygosity levels are all valid measures of genetic diversity, but each must be used in the proper context. As we attempt to discuss genetic diversity we must consider "what we want", "what we mean", and how we are going to measure it. Keywords: Pinus taeda, effective size


Download this file:

PDF document Download this file — PDF document, 47Kb

Details

Author(s): George R. Askew, Yousry A. El-Kassaby

Publication: Tree Improvement and Genetics - Southern Forest Tree Improvement Conference - 1993

Section: Closing Session