Dynamic Of Soil Organic Carbon In Surface Layer Of Erosive Degraded Red Soil During The Ecological Restoration

Taking woodland soil of artificial restored Pinus massoniana ecosystem in erosive degraded red soil as research object, this paper applied RothC26.3model to stimulate dynamic of total soil organic carbon pool and its components in surface layer (0-20cm) of woodland during the progress of recovery of Pinus massoniana in erosive degraded land,and then analysed the changes of the rate, benefits and the potential of soil carbon sequestration in different recovery period. On the basis of this, dynamics of soil carbon pool in0～20cm layer were predicted Under the condition of climate changing in the next160years. The main conclusions are as follows:1).RothC26.3model can perfectly stimulate the dynamic of organic carbon pools in0-20cm soil layers of erosive degraded red soil during the process of Pinus massoniana recovery, under the condition of Mid-Subtropical Monsoon Climate. The change trend of soil organic carbon in the progress of vegetation recovery can be well reflected in both long (R2=0.84)and short (R2=0.89) time stimulation.2).After the plantation of masson pine forest, as time goes on,the rate of carbon sequestration in surface layer (0～20cm) of erosive degraded land increases in a nonlinear way,which will reach the utmost in about15-25years, the average rate of soil carbon sequestration in short-term(30years) recovery progress and the whole succession progress is0.385tC/ha·year and0.156tC/ha·year,respectively.3). On the assumption that the the impact factors of soil organic carbon such as future climate,management etc. are invariant, the saturated carbon capacity and the potentiality of carbon sequestration of erosive degraded red soil land in study area,calculated by stimulation fitting equation, is about36.85tC/ha and33.26tC/ha, respectively.4).The change trend of different soil organic carbon fractions in the process of vegetation recovery of erosive red soil land can be perfectly(correlation coefficient r is up to0.78) reflected with RothC26.3model.But the stimulations of DPM、RPM and BIO are somehow overestimated.Especially for BIO, compared with othes, the result of stimulation is not so satisfactory.Viewing the stimulation results as a whole, the stimulation effect of RothC model for HUM is pretty good. 5).In the progress of short-term vegetation recovery, the fluctuation of soil organic carbon is mainly embodied in DPMn RPM and BIO,while the accumulation of soil organic carbon usually happened in fraction RPM of soil organic carbon. With time prolonged, HUM turned into the main form of soil organic carbon accumulation gradually.During the whole restoration, the efficiency of soil carbon sequestration ESCS decreased at the beginning,then increased gradually,and finally reached a balance.6).Under the condition of no importation of additional organic carbon or human management, the increase of average air temperature and precipitation would cause a huge lost of soil carbon pool of woodland surface floor (0～20cm).In the next160years(2012—2172), the average rate of carbon sequestration in0-20cm woodland during the progress of Pinus massoniana succession would reduced by8.65%～58.55%due to the climate changes with different extent, causing a loss of14.17%～28.94%of organic carbon storage. In a certain range of climate change, the change of precipitation may become the dominant factor affecting the dynamics of soil carbon pool of pinus massoniana ecosystem in HeTian region.