Leaf litterfall, fine root production and turnover in four major tree species of the semi-arid region of India

Litterfall and fine root production is a major pathway for carbon and nutrient cycling in forest ecosystems. We investigated leaf litterfall, fine-root mass, production and turnover rate in the upper soil (0-30 cm) under four major tree species (Leucaena leucocephala, Acacia nilotica, Azadirachta indica, Prosopis juliflora) of the semi-arid region of India. All the four tree species showed an unimodal peak of leaf litterfall with distinct seasonality. Leucaena leucocephala and Acacia nilotica had maximum leaf litterfall between September and December while Azadirachta indica and Prosopis juliflora shed most of their leaves between February and May. Annual leaf litterfall of the four species ranged from 3.3 Mg ha(-1) (Leucaena leucocephala) to 8.1 Mg ha(-1) (Prosopis juliflora). Marked seasonal variations in amount of fine root biomass were observed in all the four tree species. Fine root production was maximum in Prosopis juliflora (171 g m(-2) y(-1)) followed by Azadirachta indica (169 g m(-2) y(-1)), Acacia nilotica (106 g m(-2) y(-1)) and Leucaena leucocephala (79 g m(-2) y(-1)). Fine root biomass showed a seasonal peak after the rainy season but fell to its lowest value during the winter and dry summer season. Fine root turnover rate ranged from 0.56 to 0.97 y(-1) and followed the order Azadirachta indica > Leucaena leucocephala > Prosopis juliflora > Acacia nilotica. The results of this study demonstrated that Prosopis juliflora and Azadirachta indica had greater capability for maintaining site productivity as evidenced from greater leaf litterfall and fine root production.