Factors affecting recruitment of Pinuspungens in the southern Appalachian Mountains

Factors affecting the establishment and recruitment of seedlings of the Appalachian endemic Pinuspungens Lamb were studied in pine–oak forests of dry, southwesterly mountain slopes in southwestern Virginia, United States. Recruitment of P. pungens was not limited by seedfall from serotinous cones or by postdispersal seed predation. Total viable seedfall ranged from 35 000 to 69 000 seeds/ha in 1988 and was concentrated in the spring and summer months. Low availability of suitable seedling habitat strongly limited recruitment of P. pungens seedlings. The distributions of habitat variables for P. pungens seedlings and random points in the forest overlapped little, indicating that suitable microsites were relatively rare. Seedlings occurred in microsites characterized by shallow pine litter, low ground and canopy covers, and larger nearest neighbor distances than occurred at random. Summer drought also contributed to low seedling survivorship, particularly in young seedlings. Our results suggest that optimal recruitment and population maintenance of P. pungens in pine–oak forests is unlikely in the absence of fire.