A newly documented and significant Piedmont prairie site with a Helianthus schweinitzii Torrey & A.Gray (Schweinitz's sunflower) population

Abstract

This study documented and described a recently located (2003) and significant Piedmont prairie site (Troy Prairie) from Montgomery County, NC. From 2006–08 a complete floristic inventory was conducted. In addition, 75 quadrats (1 × 1 m) were sampled for species frequency, and 12 quadrats were sampled at 3 depths (0–10 cm, 11–20 cm, 21–30 cm) for soil chemistry to determine pH, and extractable P, K, Ca, Mg, Zn, and Mn. A total of 163 vascular plant species were identified, including 62 monocots, 97 dicots, three ferns, and one lycopsid. There were 57 (35%) graminoids and 39 (24%) Asteraceae. Of the Asteraceae, Helianthus schweinitzii (Schweinitz's sunflower) is Federally endangered, while Solidago gracillima and S. radula are both rare-listed for NC. Only five individuals of H. schweinitzii were found in this study of an estimated 100 in 2003. Eighty-seven (53%) species had previously been reported as occurring in prairie-like associations. Andropogon gerardii and Rubus sp. had the highest frequency at 48%. Troy Prairie is one of only three known A. gerardii populations in North or South Carolina > 0.5 ha. The site contains upland to hydric conditions, and 42 (26%) of the species listed were obligate to facultative wetland. The mean soil pH was very strongly acidic (4.9). Phosphorus, K, and Ca levels were low for all three sampled depths for both upland and hydric sections, while there were medium levels of Mg. A portion of the site is under current consideration for a highway improvement project.