TECHNICAL REPORTS

We present a hybrid and stand-level forest ecosystem model, DRAINMOD-FOREST, for simulating the hydrology, carbon (C) and nitrogen (N) dynamics, and tree growth for drained forest lands under common silvicultural practices. Th e model was developed by linking DRAINMOD, the hydrological model, and DRAINMOD-N II, the soil C and N dynamics model, to a forest growth model, which was adapted mainly from the 3-PG model. Th e forest growth model estimates net primary production, C allocation, and litterfall using physiology-based methods regulated by air temperature, water defi cit, stand age, and soil N conditions. Th e performance of the newly developed DRAINMOD-FOREST model was evaluated using a long-term (21-yr) data set collected from an artifi cially drained loblolly pine (Pinus taeda L.) plantation in eastern North Carolina, USA. Results indicated that the DRAINMOD-FOREST accurately predicted annual, monthly, and daily drainage, as indicated by Nash–Sutcliff e coeffi cients of 0.93, 0.87, and 0.75, respectively. Th e model also predicted annual net primary productivity and dynamics of leaf area index reasonably well. Predicted temporal changes in the organic matter pool on the forest fl oor and in forest soil were reasonable compared to published literature. Both predicted annual and monthly nitrate export were in good agreement with fi eld measurements, as indicated by Nash–Sutcliff e coeffi cients above 0.89 and 0.79 for annual and monthly predictions, respectively. Th is application of DRAINMOD-FOREST demonstrated its capability for predicting hydrology and C and N dynamics in drained forests under limited silvicultural practices