Sources of variability in net primary production predictions at a regional scale: a comparison using PnET-II and TEM 4.0 in northeaster U.S. forests. Ecosystems

Because model predictions at continental and global scales are necessarily based on broad characteriza-tions of vegetation, soils, and climate, estimates of carbon stocks and fluxes made by global terrestrial biosphere models may not be accurate for every region. At the regional scale, we suggest that atten-tion can be focused more clearly on understanding the relative strengths of predicted net primary pro-ductivity (NPP) limitation by energy, water, and nutrients. We evaluate the sources of variability among model predictions of NPP with a regional-scale comparison between estimates made by PnET-II (a forest ecosystem process model previously ap-plied to the northeastern region) and TEM 4.0 (