The Himalayan alder (Alnus nepalensis D. Don)-large cardamom (Amomum subulatum Roxb.) intercrop grown in the Middle Hills of eastern Nepal was studied as a model highland agroforestry system. Sixty-six sites were sampled and 42 farmers were interviewed in four districts of the Kosi and Mechi Zones of the Eastern Development Region to develop site index curves and quantify biomass productivity. Edaphic and physiographic parameters were correlated with site indices. Annual tree biomass production 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 thinning. Tree component standing biomass accumulation was estimated by site index classes, and used to derive a predictive equation for average total standing biomass (273 t/ha) at a plantation reference age of 25 years. Biomass and productivity estimates were correlated with results from farmer interviews and used to quantify annual cardamom production (364 kg/ha), labor requirements (237 man days/yr), and gross annual 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), were also quantified. Conservation and service functions provided by the agroforestry system are described.