Leaf litter decomposition and nutrient dynamics in four multipurpose tree species

Leaf litter decomposition is a fundamental process of ecosystem functioning which is closely linked to the nutrient supply for plant growth. Leaf litter decomposition and nutrient dynamics of four important agroforestry tree species viz., Bhimal (Grewia optiva Drummond ex Burret), Sehtoot (Morus alba L.), Tun (Toona ciliata M. Roem) and Poplar (Populus deltoides Bartr. ex Marsh.) were studied by placing the leaf litter in surface and plough/sub-surface layer for one year. Decomposition rate was highest in M. alba followed by G. optiva, T. ciliata and P. deltoides for both the placements. Sub-surface placed litter showed faster rate of decomposition than surface placed leaf litter. Rate of decomposition in all the four species was influenced significantly and positively by combined effect of rainfall and temperature. Relationship between cumulative weight loss and substrate/litter quality attributes viz., Ca, acid detergent fiber (ADF), lignin and cellulose was significant but negative. Nitrogen and water-soluble compounds (WSC) content on the other hand showed positive and significant correlation with cumulative weight loss. Nitrogen (N), Phosphorus (P), Potassium (K), Calcium (Ca) and Magnesium (Mg) dynamics in decomposing litter revealed that concentration of nitrogen, phosphorus and calcium did not follow any specific trend during the decomposition process. Potassium and magnesium concentration, however, revealed a decreasing trend throughout the study period. Changes in absolute amount, on the other hand, followed a release pattern throughout the study period for N, K and Mg. P and Ca also followed release pattern with certain fluctuations in between.