Snag dynamics and cavity occurrence in the South Carolina Piedmont

Standing dead trees, or snags, are natural components of forest stands and are important habitats for many wildlife species. We examined snag dynamics from 1982-1990 on 140 0.1 ha plots in the upper Piedmont of South Carolina . Plots were established in 10 stand type-age class combinations. Mean snag density was 28.4 snags/ha and mean snag diameter (DBH) and height were 20. 3 cm and 9.9 m, respectively. Highest snag densities occurred in hardwood s tand types; pine plantations had lower (p less than or equal to 0.05) snag density than all other types. Within a particular stand type, snag densitie s, recruitment rates, and loss rates generally were lowest in the oldest ag e classes. Intermediate age classes of all stand types had higher snag dens ities and snag turnover rates than younger or older stands within that type . Young pine plantations had the lowest recruitment rate ((x) over bar=1.79 snags/ha/year) and old pine plantations had the lowest loss rate ((x) over bar=1.59 snags/ha/year) of all the stand type-age class combinations. Alth ough twenty species of snags were observed, five species/species groups, sh ortleaf pine (Pinus echinata), red oaks (Quercus spp.), white oaks (Quercus spp.), loblolly pine (P. taeda), and yellow poplar (Liriodendron tulipifer a), occurred most frequently. Snag DBH and cavities/snag were not significa ntly correlated. Stage of decay for cavity and noncavity snags (r=0.97 and 0.83, respectively; p less than or equal to 0.05) and number of cavities/sn ag (r=0.78) increased with year since snag recruitment. Ten snag species co ntained cavities ((x) over bar=0.1 cavities/snag), but shortleaf pine accou nted for 56% of the cavity years observed ((x) over bar=0.18 cavities/snag) . Three other softwood species also contained equal to or above average num bers of cavities/snag. Approximately 30% of all snags fell within two years of recruitment, 55% within three years, and 95% within six years. Snag lon gevity was independent of diameter class (p=0.67). Hardwood snags, especial ly those in upland hardwood stands, appeared to persist longer than pine sn ags. As pine plantations managed on short rotations (<25 years) and older-a ged stands (>50 years) of all types may not provide abundant snags in the S outh Carolina Piedmont, the potential for wildlife habitat might be enhance d if older, larger diameter trees, especially softwood species, are retaine d or designated as snag replacements. (C) 1999 Elsevier Science B.V. All ri ghts reserved.