A flora of the Rock Hill Blackjacks Heritage Preserve, York County, South Carolina

Castanea, Sep 2002 by Schmidt, John M, Barnwell, James A

ABSTRACT

The Rock Hill Blackjacks Heritage Preserve was recently established, partly within the city limits of Rock Hill, South Carolina. It showed evidence of moderate to severe human disturbance including the effects of agriculture, forestry, construction of utility rights-of-way, and abandoned roads. Despite its small size and obvious disturbance, the preserve supported over 400 species of vascular plants. The reasons for this unusual level of diversity are not entirely clear. Geology was one factor. The preserve is underlaid by the Rock Hill gabbro/metagabbro pluton. Thin soils and seasonally wet areas provided a mixture of wetland and dryland species. It contained six distinct plant communities: 1) Bottomland Forest, 2) Gabbro Glade, 3) Montmorillonite Forest/Woodland, 4), Old Field Grassland/Shrubland, 5) Old Field Woodland, and 6) a distinct Grassland/Shrubland in the utility rights-of-way. The greatest diversity, including many tall-grass prairie species, was in the utility corridors that crisscross the preserve.

INTRODUCTION

In 1995, the establishment of the Rock Hill Blackjacks Heritage Preserve (RHBHP) protected a 117.3 hectare piece of a globally endangered community. Part of the preserve is located within the city limits of Rock Hill, South Carolina which is experiencing a rapid increase in its population because of its proximity to Charlotte, North Carolina 33 km (20 mi) to the north. The preserve is surrounded on three sides by housing developments and will likely become an island within the city. A comprehensive survey of the vascular plants within the preserve was undertaken to serve as a baseline to monitor biological changes that will inevitable take place as the result of urbanization.

A less comprehensive survey was also conducted to the east and south of the preserve because of its similar geological and botanical affinities. It is hoped that the preserve will continue to expand eastward, as it did in 2000, to include a substantial number of locally rare species that are outside the protection of the preserve. Timber harvesting, mining, herbicides, and commercial development currently threaten this area.

Human History

Before European colonization, the area that is now the preserve was part of the tribal lands of the Catawba Nation. Much of their history has been lost, but reports of early settlers indicate that there were large savannahs in the area of Rock Hill (Barden 1997, Nelson 1992). Presumably these areas were maintained by fire, both accidental and manmade. The fires were set for many reasons including hunting, wildlife management, agriculture, and defense. Europeans continued the practice of burning into the 20th century to clear land for farming and to maintain forage for game.

The land that makes up the preserve has a long history of human disturbance. Parts of the preserve have been variously used as pasture, a dumpsite, a prospective housing development, a loblolly pine plantation, and for farming, timber, and utility rights-of-way. The unusual floral diversity owes its existence in part to the failure of these enterprises, with the exception of the maintenance of the utility corridors.

Barbed wire fencing indicates that part of the land was recently used as pasture. A section of the fencing follows one of the utility rights-of-way and was probably constructed after the easement was established in 1948. Aerial photos show a steady shrinkage of the nonforested or glade-like areas, with the exception of the utility rights-of-way, from 1965 until the present (Camp 1965). This may be the result of fire suppression. In a recent experiment, trees were felled in order to create openings in the forest adjacent to a utility corridor. The oldest tree was 50 years old in 1997 (P. Johnson, unpubl. data). The diameter of this oak tree was typical of the larger trees in the preserve and dates the last timber harvest to the late 1940's. A more recent attempt at tree farming using loblolly pine has adversely affected the understory in some areas through canopy shading and thick leaf litter accumulation.

In the early 1980's, roads were cut for a proposed housing development, but the plan was abandoned at least partially because of the high water table. The field near the entrance was used as a hay field up until its purchase in 1995. Despite the protected status of the preserve, areas near its entrance road continue to be used as dumpsites.

The unusual flora was first brought to the attention of scientists in 1982 when a Duke Power employee noted vegetation native to prairies growing in a transmission right-of-way (J. Garton, pers. comm.). The first thorough survey of the region was conducted by John Nelson (1987) for the South Carolina Department of Natural Resources Heritage Trust Program. His report identified many unusual plant communities and species, including Helianthus schweinitzii which was listed as an endangered species in the Federal Register in 1991. It was this discovery that eventually led to the establishment of the preserve in 1995. Additional lands purchased in 1996 and 2000 have expanded the preserve to a total area of 117.32 hectares (~~290 acres).