A Preliminary Study on the Carbon Dynamics of China’s Forest Ecosystems in the Past 20 Years

Carbon balance is characterized by the net ecosystem productivity (NEP), the difference between net primary productivity (NPP) and the heterotrophic respiration (Rh), namely the decomposition of dead organic matter by soil microbes. At the global scale, NEP is of great interest because it indicates the capacity of terrestrial ecosystems absorbing/releasing CO2 from/to the atmosphere. In this paper, we briefly review some of the research efforts that are related to the carbon balance of China. Direct field measurement of Rh is rare because separating root respiration (Rr) from the total soil surface CO2 efflux is very difficult. Although the current global terrestrial ecosystems are most likely at non-equilibrium state due to various disturbances, such as fire, deforestation, and land-use change, as well as climate and atmospheric changes, we report in this paper our initial attempts towards the determination of carbon balance of China based on a new technique for estimating soil Rh. Based on the fact that at the equilibrium state NPP equals Rh, using NOAA AVHRR data and field NPP measurements we estimated the NPP of China’s forest ecosystems between 1982–1998. Therefore, we were able to present preliminary results of NEP obtained for China’s forest ecosystems.