Abstract: Forest ecosystem model is an effective tool for providing decision on forest resource management.PnET was established on the framework of interdisciplinary studies by the Complex Systems Research Center,USA. Though primarily a temperate forest canopy model,work is currently underway to generalize PnET and produce a simple,alternative model applicable to simulate carbon,water and nitrogen flux for all terrestrial ecosystem types.Current literatures revealed that PnET could be applied in wide zone,including America,Europe and Asia.PnET model is a useful tool to analyze forest growth,effect of different soil types and climate conditions on carbon,nitrogen and water flux of forest ecosystem.In addition,it can be used as predictor to estimate potential production of forest ecosystem in changing environment and provide information for improving land use efficiency.

Key words: Forest ecosystem, Forest ecosystem, Carbon-nitrogen-water circle, PnET model