PRWI Sites
Prince William Forest Park Permanent Lichen Biomonitoring Sites in PRWI The Prince William Forest Park is a 15,000 acre piedmont forest located 35 miles south of Washington, D.C. The park contains several rare communities, including a seepage swamp, remote stands of eastern hemlock, and several populations of rare plants. Upland slopes are dominated by mixed oak stands and lower elevations support mesic hardwood stands. Lichens are common throughout the park, especially on wind-thrown trees and branches. PRWI sites In 2004, 44 permanent lichen biomonitoring sites were located in 1 km2 grids within the park, and a baseline sampling for lichen floristic and elemental data was done. At each location, abundance of tree-inhabiting macrolichens was recorded and  a specimen of the common lichen Flavoparmelia caperata was collected for elemental analysis. Links are available to the PRWI lichen species and PRWI element data collected at each sampling location. Comparative summary data for all sites in the NCR are also available. PRWI lichens Corticolous macrolichen communities in PRWI are typical of Piedmont hardwood stands found in the Park. Dominant species include Flavoparmelia caperata (the species used in elemental analysis), Punctelia rudecta, Pyxine sorediata, Parmotrema spp., Phaeophyscia rubropulchra, Physcia millegrana, and Myelochroa aurulenta. Physcia aipolia is very common on wind-thrown branches. Species known to be sensitive to air pollution include Usnea spp., and the cyanolichen Leptogium cyanescens. PRWI elements Element concentrations in samples of F. caperata collected in PRWI are signficantly lower than for all other park units studied (descriptive summary statistics available here). This is especially notable for S and Pb. PRWI maps available from NPS NCR Lichens Home