Modelling the net primary productivity of temperate forest ecosystems in China with a GAP model

The dynamics of net primary productivity (NPP) and biomass of temperate forests Northeastern China was examined by comparing field data with simulation results from the ZELIG model. For broad-leaf/Korean pine mixed forests, biomass was estimated between 198 and 370 Mg ha−1 (dry weight), and NPP was estimated at 8–20 Mg ha−1 per year (dry weight). The simulation results indicate that NPP in mixed forests would discontinuously increase over the next 200–400 years, to a maximum value of 21 Mg ha−1 per year. Simulation of biomass dynamics suggests that it would peak in about 300 years at approximately 400 Mg ha−1, and then slowly decline. For oak forests, simulated NPP ranges from 5 to 13 Mg ha−1 per year, with biomass estimated at 120–310 Mg ha−1. In aspen–birch forests, maximum NPP and biomass values were 18 Mg ha−1 per year and 320 Mg ha−1, respectively, while minimum NPP and biomass values were 7 Mg ha−1 per year and 50 Mg ha−1, respectively. Larch forests were found to have lower values of NPP and biomass than other forest types, with NPP between 5 and 12 Mg ha−1 per year, and biomass between 50 and 275 Mg ha−1. Comparison of measured field data with ZELIG simulated values indicates only a 8–13% error, based on more than 50 independent plots, with a mean accuracy for simulated NPP between 88 and 93%.