Title: Silvicultural Effects on Genetic Diversity: Lessons from Eastern White Pine.
Summary: Several studies using isozyme and DNA markers have addressed silvicultural impacts on genetic diversity and population genetic structures of eastern white pine stands. Populations become genetically structured when neighboring trees are more closely related than more distant trees. This occurs through mating among relatives brought about by limited seed and pollen dispersal and can increase the level of inbreeding within stands. This kind of population structure is common in mature undisturbed stands. It can be made to decrease or disappear in properly thinned stands resulting in less inbreeding and higher heterozygosity in naturally regenerated stands, as evident in the Menominee white pine forests of Wisconsin. Thinning also can remove rare gene variants, however. Such loss would seem to threaten the genetic adaptability of the stand to environmental changes, at least at the margins of the species’ range. Yet, the evidence from other studies suggests that as long as basic gene diversity and gene flow among geographic areas are maintained then evolutionary processes remain intact and populations can quickly adapt to changing environments.
Presenter: Craig S. Echt, Research Geneticist, US Forest Service, Southern Experiment Station, Southern Institute of Forest Genetics, Saucier, MS; Adjunct Professor, Dept. of Ecosystem Science and Management, Texas A&M University, College Station, TX.
Dr. Echt received his doctorate in Genetics from Indiana University (Bloomington). He has been a Research Geneticist with the United States Forest Service for 12 years and was Project Leader of the Application of Genomic Sciences Project for four years at Forest Research, New Zealand. His research interests include development of DNA markers, genome mapping, and population genetic studies for pines and other forest plant species.