Seed Sourcing for Longleaf Pine Herbaceous Understory Restoration: Little Bluestem (Schizachyrium scoparium) and Hairy Lespedeza (Lespedeza hirta) Restoration Genetics

摘要

Restoration of the herbaceous understory community of the longleaf pine ecosystem is limited by the availability of appropriate seeds. To understand the relationship of seed transfer zones and genetic composition of two co-occurring species of the herbaceous understory, seeds of little bluestem (Schizachyrium scoparium) and hairy lespedeza (Lespedeza hirta) were collected from five provisional seed transfer zones across the historical range of the longleaf pine ecosystem in the North American Coastal Plain as well as a commercially available seed source originating from outside this range. To determine the genetic structure and diversity of these plants within the seed transfer zones and the commercial source, microsatellite and inter-simple sequence repeals (ISSR) markers were used for little bluestem and hairy lespedeza, respectively. For both species, plants from within the five seed transfer zones were genetically distinct from the commercial source from Kentucky. Little bluestem and hairy lespedeza plants from two provisional seed transfer zones were more genetically similar to each other than they were to other seed zones, which could justify merging these two zones. The genetic relationships among the remaining seed zones, including the commercial source from Kentucky, roughly follow geographic proximity, with genetic similarity decreasing as a function of geographic distance. Most of the genetic variation was partitioned within and less among seed zones, despite documenting significant differences among seed zones. The results of this study support the sub-The Nature Conservancy ecoregion seed transfer zones while acknowledging species-specific differences among seed transfer zones for the longleaf pine ecosystem.