NPP TEMPERATE FOREST: GREAT SMOKY MOUNTAINS, TENNESSEE, U.S.A., 1978-1992

Productivity of old, unlogged stands of southern Appalachian cove forest was studied and compared to young stands. Tree growth increments and allometric relationships were the basis for estimation of NPP. Measurements of tree diameter at 1.37 m above ground were made at the beginning the study. Radial increment cores were taken from a subset of trees. Above-ground net primary production (ANPP) was estimated using regional species-specific allometric relationships for tree mass. Estimation procedures were outlined by Busing et al. (1993).Old stands of mixed deciduous (and mixed deciduous-Tsuga) were selected for their gentle terrain, accessibility and history of study. From 1988 to 1992, seven old-growth stands were sampled with plots (0.6-1.0 ha each). The total area of old-growth forest sampled was 5.4 ha. Radial increments over the previous decade were used to provide estimates of tree diameter growth. Young stands, dominated by the deciduous species Liriodendron tulipifera, provided comparative information.The climate is perhumid mesothermal with seasonal temperature variation, but precipitation is distributed throughout the year. The Gatlinburg SW, Tennessee station mean annual temperature is 13.2 degrees centigrade. Mean annual precipitation is 141 cm. Detailed long-term climate data for this station are available from the Southeast Regional Climate Center (http://www.dnr.state.sc.us/climate/sercc/). The Gatlinburg SW station is at 445 m asl, whereas the study sites are at elevations from 720 to 1140 m. The Alum Cave Bluffs Parking Area station at 1173 m asl is more representative of the study sites, but long-term data are not readily available. Shanks (1954), Stephens (1969), and Busing et al. (2005) have documented the 1947-1950 data from this station (http://water.usgs.gov/pubs/ds/2005/115/). Mean annual temperature is 9.9 degrees centigrade. Mean annual precipitation is 200 cm. Estimates of annual ANPP for stands of various ages ranged from 6 to 13 Mg/ha. Stand biomass of the old stands was high for temperate deciduous forests (>300 Mg/ha above ground); however, ANPP was average (6-10 Mg/ha/yr) and tended to be lower than that of young stands (12-13 Mg/ha/yr) on similar sites.