A Study Of Several Terrestrial Ecosystem Carbon Cycle Of China

The research used Miami(Thornthwaite, Chikugo, Zhu Zhihui and Zhou Guangsheng) five kinds of models to estimatie net primary productivity NPP of terrestrial ecosystem in China. The variation of NPP during1970-2009, and the relationship between NPP with temperature and precipitation were analyzed.Form the space distribution of the research, it indicates the value of south and northeast area is higher, it is caused by the higher level of the temperature and precipitation in north area, and the higher soil organic carbon storage in northeast. However, because of the low rainfall and low soil organic carbon storage in inland of northwest and Tibetan plateau, the net primary productivity in there is lower.The values of NPP estimated by5models are much the same, annual variation is2.83-3.53Pg·C·yr-1,and the soil respiration is about3.19Pg·C·yr-1in these40years. This study through Luo Tianxiang and Ceng Huiqing estimate the value of different regions of the NPP based on five kinds of estimate the value of the model validation, into a significant direct ratio relation. The major factors concerned in these5models are temperature and precipitation, but consider few about the soil, landform conditions and plant physiological ecology factors, and these models have their limitations. So the effect of net primary productivity of terrestrial ecosystems to future climate change needs to be further researched.The paper uses the models researched by Bond-Lamberty:Rhl=e(0.73ln(Rs)+122), Rh2=e(0.87ln(Rs)+0.22),Rh3=e(0.88ln(Rs)+0.20) to estimate soil heterotrophic respiration in China, and analyses the relationship between climate factors and soil heterotrophic respiration in1970-2007. The result indicates the soil heterotrophic respiration can be divided into south area, inland of northwest and Tibetan plateau, northeast and North China in space distribution. The heterotrophic respiration increases with soil respiration, the heterotrophic respiration represents34%-94%of soil respiration, and the average is65%. After analysis, the values of heterotrophic respiration obtained by empirical model are comparable with observations. soil heterotrophic respiration soil heterotrophic respiration soil heterotrophic respirationThe estimates of net ecosystem production of terrestrial ecosystem in China is based on the model NEP=NPP-Rh. The value of net ecosystem production is estimated from1970to2009, the results and space distribution has been analyzed. From the estimation results, the range of NEP1is0.278-0.607Pg·C·yr-1, the NEP2is0.676-0.851Pg·C·yr-1, and the NEP3is0.436-0.724Pg·C·yr-1. Research shows that the correlation between heterotrophic respiration and annual average precipitation is higher than the annual average temperature, and the limitation of the precipitation to heterotrophic respiration is greater than the temperature.The paper estimates the mean residence time of soil organic carbon in China between1970and2009with the formula MR T=SOC/Rh=m0e(αT+βAP+γSN) The results show that there are differences between annual net primary productivity of terrestrial ecosystem in1970-2009, the range of variation isl5.55-17.12yr, and the average amount of soil respiration isl6.45yr in these40years. Although this evaluation method has certain rationality, but the estimation with GIS relies on the results of heterotrophic respiration and soil nitrogen storage. What’s more, the complexity and heterogeneity of terrestrial ecosystem make the errors become larger, so the estimation accuracy of the mean residence time of soil organic carbon is pending further development.