Chemical characteristics and decomposition patterns of six multipurpose tree species, viz., Alnus nepalensis, Albizzia lebbek, Boehmeria rugulosa, Dalbergia sissoo, Ficus glomerata and F. roxburghii were analysed in a mixed plantation established on an abandoned agricultural land site in a village at 1200 m altitude in Central Himalaya, India. Differences in chemical quality of litter species were most marked in polyphenol and N concentrations. A. lebbek, A. nepalensis and D. sissoo showed higher N (2.2–2.6%) but lower polyphenol concentrations (3.2– 4.7%) than B. rugulosa, F. glomerata and F. roxburghii (0.96 –1.97% N and 5.68–11.64% polyphenol). Significant effects of species, incubation time and species × incubation time interaction on monthly mass, N, P and K release rates were observed. A linear combination of rainfall and temperature explained the variation in monthly mass loss better than rainfall and temperature independently. Percentage mass remaining after 1 year of incubation varied from 30 to 50, N remaining from 40 to 86, P remaining from 33 to 56 and K remaining from 1 to 3. Annual decomposition constants of mass and N were positively correlated with C and N concentrations and negatively correlated with C/N, lignin/N, polyphenol/N and lignin+polyphenol/N ratios of fresh litter. As all the species studied showed the highest rates of N and P release during the rainy season, rainy season crops are not likely to be as much nutrient stressed as winter season crops if leaf litter of these species is assumed to be the sole source of nutrients to crops in tree-crop mixed agroforestry. A. lebbek, A. nepalensis, D. sissoo and F. glomerata seem to be more appropriate for rapid recovery in degraded lands as their litter decomposed faster than B. rugulosa and F. roxburghii. A diverse multipurpose tree community provides not only diverse products but may also render stable nutrient cycling.

Introduction

Land degradation is a major problem all through the Himalayan mountain system covering eight developing countries of South Asia including Afghanistan, Bangladesh, Bhutan, China, India, Myanmar, Nepal and Pakistan. Plantations of multipurpose trees alone or combined with agricultural crops could be an e4ective land rehabilitation strategy. Litter production, decomposition and nutrient release patterns determine the potential of tree species to improve soil fertility and productivity in degraded lands. Though many studies on decomposition and nutrient release from agroforestry species are available, efforts in the Himalayan region are limited. The aim of this study was to compare decomposition and nutrient release patterns of six multipurpose tree species in Indian Central Himalaya.