This NPP data set contains one ASCII file (.txt format). The data file contains above- and below-ground biomass, litterfall, LAI, vegetation/soil micro-nutrient content (P, K, Ca, Mg, etc.), and above-ground net primary productivity (ANPP) estimates for transitional moist/dry tropical forests at Rio Lara (wet season site) and Rio Sabana (dry season site) in Darien Province, Panama. Field ... measurements were made in 1967 and 1968. No climate data are provided. Apart from litter quantity, most of the differences between these data reflect variations between the two plots sampled, rather than seasonal changes. Both plots were considered representative of the surrounding forest. The area was thought to have been forested for the previous 400 years, following abandonment of open savanna lands maintained by the Precolumbian Indians. Total annual leaf and branch fall averaged for the two sites was 1,137 g/m2/yr, representing a minimum ANPP estimate. Litter decomposition over the 9-month wet season was around 90%. LAI at both sites was high; however, the index for the dry site (10.6 m2/m2) was only half that of the wet season site (22.4 m2/m2).