Nutrient Release through Decomposition in Different Plantations at New Forest of Doon Valley

The paper deals with the nutrient release through decomposition in four plantations of Shorea robusta (sal), Tectona grandis (teak), Pinus roxburghii (pine) and Eucalyptus spp. at Forest Research Institute Demonstration Area, Dehra Dun (India). Per cent nitrogen content in litter-bags increased with time in both leaf- and twig-litter. The initial increment of nitrogen content during early months showed its immobilization. Mineralization took place during later period of decomposition. Per cent phosphorus content increased in decomposing leaf-litter while decreased in twig-litter. P-loss in absolute content was in the order: teak (70.7%) > sal (53%) > pine (52.36) > eucalypts (26.41%). In twig-litter, the loss was almost same (70%) in all the species. N- and P- loss in leaf - litter followed almost similar pattern to dry weight loss. Potassium loss was rapid during the initial months and consistent during the later period of decomposition. K-loss may be accounted for leaching. Calcium loss in leaf-litter was much less than K and Mg in teak and sal. It was also less than K but exceeds Mg in case of pine and eucalypts. The highest Ca-loss was recorded for pine and sal (83%) > teak (78%) > eucalypts (68%) for leaf -litter. The per cent Mg content decreased in leaf- litter of all species except eucalypts. Weight loss of Mg was also rapid during initial months. It may be accounted for leaching. Overall higher Mg loss was reflection of increased C/Mg ratio.