Historical considerations of conifer expansion in Maryland serpentine “barrens.”

Conifers have spread rapidly in four protected serpentine areas in Maryland during the past 50 years. In three areas, more than 80% of grassland and savanna seral stages have succeeded to woodland and forest dominated by Pinus virginiana or this species with Juniperus virginiana. Before settlement was effected circa 1750, Native American fire hunting practices maintained vast areas of serpentine grassland and oak savanna. After settlement, livestock grazing apparently replaced Indian fires as the primary factor inhibiting woody plant succession in many areas including Soldiers Delight. Areas not grazed succeeded to forest, probably deciduous, and the regional abundance of these relatively fire-intolerant conifers probably increased substantially. Cessation of grazing and other disturbances such as logging by the mid-1900s apparently have allowed these conifers to spread rapidly in remaining serpentine openings. Although seasonal drought may slow the rate of conifer succession, extant grasslands and savannas will disappear without major perturbations such as logging and fire.