This data set contains two data files (.csv format). One file contains site characteristics, stand descriptors, and above-ground biomass and ANPP data for seven old-growth temperate forest stands and one young cove forest stand in the Great Smoky Mountains of Tennessee. The old-growth stands (> 200 years old) span several watersheds on the north slope of the mountains at elevations ranging from 720 to 1,140 m. The younger stand (48-63 years old, elevation 910 m) developed after agricultural abandonment. The second file contains monthly mean climate data averaged over four years (1947-1950) from four climate stations located along an elevational gradient (445-1,920 m) in Great Smoky Mountains National Park. DBH measurements were made at the beginning of the study and biomass increment was measured from a subset of trees. ANPP was estimated using regional species-specific allometric relationships for tree mass. Biomass, volume, and annual input of coarse woody detritus are also reported. Live biomass in the old-growth stands (32,600-47,100 g/m2) is among the highest reported for temperate forests of eastern North America while ANPP is moderate (630-1,010 g/m2/yr). ANPP in the younger stand was higher (1,180-1,310 g/m2/yr). In comparison with forests worldwide, inputs of coarse woody debris is moderate. Revision Notes: Previously reported field collection dates have been corrected in the NPP file. Biomass and ANPP values were converted from Mg/ha and Mg/ha/yr to g/m2 and g/m2/yr, respectively, consistent with units in other files in the NPP collection. Please see the Data Set Revisions section of this document for detailed information.