STRUCTURE AND FUNCTION OF AN AGE SERIES OF POPLAR PLANTATIONS IN CENTRAL HIMALAYA .1. DRY-MATTER DYNAMICS

The biomass and net primary productivity (NPP) of 5- to 8-year-old poplar (Populus deltoides Marsh, Clone D-121) plantations growing in the Tarai belt (low-lying plains with high water table adjacent to foothills of central Himalaya) were estimated. Allometric equations for all the above-ground and below-ground components of trees and shrubs were developed for each stand. Understorey, forest floor biomass, and litter fall were also estimated from stands. The biomass of plantation, forest floor litter mass, tree litter fall and net primary productivity (NPP) of trees and shrubs increased with increase in plantation age, whereas herb biomass and NPP significantly (P < 0.01) decreased with increasing plantation age. The total plantation biomass increased from 84.0 in the 5-year-old to 170.0 t ha(-1) in the 8-year-old plantation and NPP from 16.8 t ha(-1) year(-1) in the 5- and 6-year-old to 21.8 t ha(-1) year(-1) in the 8-year-old plantation. The biomass accumulation ratio (biomass:net production, BAR) for different tree components increased with the age of plantation increase. The BAR ratio ranged from 4.9 in the 5-year-old to 7.7 in the 8-year-old plantation. (C) 1995 Annals of Botany Company