Construction Application Of Spatiotemporal Carbon Cycle Model Of Moso Bamboo Forest Ecosystem

Carbon cycle of forest ecosystem is a key factor in modulating the atmosphere CO2 sink/source,and play a significant role in global climate change.Bamboo forest is a special and important forest type distributed in subtropical zone,and has a great carbon sink capability.However,the source-sink process of bamboo forest was easily effected by human activities.At present,the research related on characteristic of carbon accumulation and photosynthetic ecophysiological responding in new-shoot bamboo,characteristic of carbon and water flux at site scale,quantify estimation of carbon storage of bamboo forest using remote sensing data,effecting of management measures on soil carbon pools,and stand structure influence on carbon sink capability have been achieved.However,the understanding of formation mechanism of spatiotemporal pattern and regulation mechanism of carbon sink/source of bamboo forest ecosystem at large scale is still very limited,and how to balance the characteristics of bamboo ecosystem and production,and guide the management of improving the carbon fixation capability of bamboo ecosystem also lack theoretical basis.In this study,the BIOME-BGC model was creatively improved to adapt the special ecophysiological process and management measures of bamboo forest.The spatiotemporal dynamics of carbon storage and carbon fluxes of bamboo forest were simulated using the improved model based on plot investigation data,carbon flux tower observation data,and MODIS products,its forming mechanism was revealed.On this basis,the relationship between management and bamboo forest production and carbon sink capability was analyzed,and the current bamboo forest management measure was optimized for providing a new theoretical guiding of improving the productivity and carbon sink capability of bamboo forest.Mainly results and conclusions were as followed:(1)Development process-based model for bamboo forest.This study developed a process-based model for bamboo forest,accuracily simulated the carbon fluxes and aboveground carbon(AGC)storage of bamboo forest.The main conclusions are as follows: 1)The age structure,on-and off-year growth,new bamboo growth,litter fall process,and four important management mesures(digging bamboo shoots,selective cutting,obtruncation,fertilization)were integrated to BIOME-BGC model in order to quantify the functioning of bamboo forest ecosystems.Obtained a set of ecophysiological parameters suitable for bamboo forest carbon cycle simulation.2)Evaluated the accuracy of modeled carbon fluxes and AGC using the observations,with average correlation coefficent of 0.73,which is 64.42% higher than the original model,and the error was 77.49% lower than original model.the simulated AGC was highly consisted with the observed data,the average correlation coefficent reached 0.81 and the root-square-mean error was 2.92 Mg C·hm-2.(2)Spatiotemporal patten and heterogeneity of bamboo forest.Analyzed the spatiotemporal patten of carbon fluxes and AGC of bamboo forest in Zhejiang Province,and studied spatiotemporal heterogeneity of AGC based on geostatistical theory.The main conclusions are as follows: 1)The spatiotemporal patten of carbon fluxes consistent with AGC during 2003-2014.Take AGC for example,the AGC is increasing from 2003 to 2014,and its high value area is distributed from sparse distribution to large area.Stands with high AGC density values are distributed in the mountainous areas in the northwest,southwest,and northeast of Zhejiang Province,while low AGC density stands are located in the mountain basin,high altitude areas,and the majority of coastal areas.In the 12 years,the area with AGC more increased was consistent with changing trend of its distribution,while the area with AGC more decreased was scattered distributed in the province.2)The AGC of bamboo forest showed an increasing tendency during 2003-2014.The AGC density increased from 12.02 Mg C·hm-2 to 18.15 Mg C·hm-2 with an average annual growth rate of 3.49%.The total AGC storage increased from 9.22 Tg C to 16.42 Tg C with an average annual growth rate of 4.93%.3)Spatial heterogeneity of AGC storage of bamboo forest in Zhejiang Province can be expressed by exponential model.The spatial autocorrelation of AGC storage of bamboo forests in Zhejiang Province from 2003 to 2014 was characterized by significant autocorrelation,and mainly due to the structural factors,environmental factors(temperature,CO2 concentration,radiation,and precipitation)and terrain factors(slope,aspect,and elevation)has a significant impact.However,the autocorrelation range lowered significantly during 2003-2014,indicated that the influence of random factors(e.g.management levels,management measure,et al.)on AGC should not be ignored.3)Optimizing the management measures for improving the carbon sink capability of Moso bamboo forest.Different management measures effect on carbon cycle of bamboo forest was firstly analyzed.The changes of carbon cycle of Moso bamboo forest under different cutting time,cutting interval and cutting intensity were studied to finding the optimum cutting mode of Moso bamboo forest.The main conclusions are as follows: 1)The model simulations of different management scenarios showed that human disturbance has a great influence on the carbon stocks and fluxes in Moso bamboo forest,especially the fertilization and selective cutting measures.2)Consider of the vegetation carbon storage,productivity,and net ecosystem exchange,winter is the best cutting season and cutting at every other year is the best cutting interval.3)The optimal selective cutting measure should be cutting 30% culms of age 6,80% culms of age 7,and all culms above age 8.The vegetation carbon storage and yield of this selective cutting method can increase by 74.63% and 21.50%,respectively,compared with the current measure(completely cutting 4 year and above).4)Implementation of bamoo forest carbon cycle model.Based on the C# programming language,the system realizes the visualization settings of the model control and ecophysiological parameters,intelligently reads input and output data.The system runs in multi-thread mode,which greatly improves the simulation efficiency of regional carbon cycle simulation.The output of the system can be directly processed and analyzed by GIS software,which provides favorable support for further study on the carbon cycle of bamboo ecosystem.