Soil Seedbank of Rare Plant Communities Associated with Diabase Soils in Durham and Granville Counties, North Carolina

Abstract

ABSTRACT WALKER, ANDREW SCOTT. Soil Seedbank of Rare Plant Communities Associated with Diabase Soils in Durham and Granville Counties, North Carolina (Under the direction of Dr. Jon M. Stucky).

In Northeastern Durham County and Southwestern Granville County, North Carolina, there are a cluster of unique, species-rich plant communities associated with diabase soils. These communities are characterized by an abundance of shade-intolerant forbs with prairie affinities, including the federally endangered smooth coneflower, Echinacea laevigata. Monitoring reports of E. laevigata indicate that, while most populations declined between 1988 and 2002, the population at Picture Creek Diabase Barren increased dramatically, presumably in response to a prescribed fire and canopy clearing associated with a power line right of way. This suggested the possibility that E. laevigata and other rare plants form a persistent soil seed bank which can contribute to population increases. Presence of a soil seed bank could have conservation value and facilitate restoration of other “prairie remnants†in the area. We tested the soil seed bank at Picture Creek and two other nearby locations which have similar floras and were reported to have had similar numbers of E. laevigata in 1988. We also tested the litter layer at Picture Creek. No rare plants were found in the soil seed bank, but a few were recovered from the leaf litter.