High-Resolution Mapping of the Net Primary Productivity of Terrestrial Ecosystems in East Asia Using a Process-Based Model

This paper presents a high-precision map of terrestrial net primary productivity (NPP) in East Asia (20° to 60° N, 100° to 170° E; 10.4×106km2), using a high-resolution process-based model (Sim-CYCLE). Using recent datasets of land cover (46 types), soil, and topography, an NPP map of East Asia was obtained, at the spatial resolution of as high as 5-minutes: i.e., 6 to 12 times finer than previous ones. The calculated NPP values were compared with observations and several other models, to verify the model validity. Total annual NPP, 5.06 Pg C, was close to those with empirical models, and seasonal variation in NPP was consistent with that based on remote sensing data. Based on the estimated NPP, radiation-use efficiency (average 0.28 g C MJ-1 PAR) and water-use efficiency (average 1.54 g C kg-1 evaporation) were calculated. The new mapping was especially effective for retreiving spatial heterogeneity due to steep topography and intensive land-use conversion, which was overlooked in previous coarse mappings. Compared with other approaches based on empirical relationships or satellite data, the process-based model is advantageous for exploring whole carbon dynamics (i.e. net ecosystem production) and future projection.