SITE INDEX AND BIOMASS PRODUCTIVITY ESTIMATES FOR HIMALAYAN ALDER-LARGE CARDAMOM PLANTATIONS - A MODEL AGROFORESTRY SYSTEM OF THE MIDDLE HILLS OF EASTERN NEPAL

The Himalayan alder (Alnus nepalensis D. Don)-large cardamom (Amomum s ubulatum Roxb.) intercrop grown in the Middle Hills of eastern Nepal w as studied as a model highland agroforestry system. Sixty-six sites we re sampled and 42 farmers were interviewed in four districts of the Ko si and Mechi Zones of the Eastern Development Region to develop site i ndex curves and quantify biomass productivity. Edaphic and physiograph ic parameters were correlated with site indices. Annual tree biomass p roduction was estimated at 14 t/ha/yr for a typical plantation cycle, with an average 11 t/ha/yr annual increase in standing biomass after t hinning. Tree component standing biomass accumulation was estimated by site index classes, and used to derive a predictive equation for aver age total standing biomass (273 t/ha) at a plantation reference age of 25 years. Biomass and productivity estimates were correlated with res ults from farmer interviews and used to quantify annual cardamom produ ction (364 kg/ha), labor requirements (237 man days/yr), and gross ann ual income (US $864/ha). Fuelwood requirements for cardamom processing (2.6 t/ha/yr), and removal of wood through thinning (3.2 t/ha/yr), we re also quantified. Conservation and service functions provided by the agroforestry system are described.