Response of the Summer Terrestrial Carbon Cycle in the East Asian Monsoon Region to East Asian Monsoon

The temporal and spatial variability of the terrestrial ecosystem in the East Asia monsoon region reveals an obvious response characteristic to the monsoon climate. The Empirical Orthogonal Function (EOF) method is used to analyze the temporal and spatial distribution characteristics of Gross Primary Production (GPP), Net Primary Production (NPP), Net Ecosystem Production (NEP), and vegetation and soil respiration in the summer terrestrial ecosystem of the East Asian monsoon region obtained for the period 1953-2004 by off-line simulation of the Atmosphere Vegetation Interaction Model version 2 (AVIM2). In addition, the mechanism of influences of the East Asian monsoon on the terrestrial carbon cycle is discussed. Results show that during strong monsoon years with lower amounts of rainfall and higher temperatures in the Yangtze-Huaihe River basin, such restricted rainfall limits photosynthesis, which leads to lower GPP values. In southern China, however, rainfall amounts and temperatures are higher, which leads to stronger vegetation and, thus, higher GPP values. Because the East Asia summer monsoon does not significantly influence both plant and soil respiration, the changes in NPP, which marks the difference between GPP and vegetation respiration, and in NEP, which marks the difference between NPP and soil respiration, are consistent with that of GPP. During the strong summer monsoon years a hot and dry climate condition in the Yangtze-Huaihe River basin reduces NPP and NEP, whereas in Southern China the hot but wet climate increases NPP and NEP.