Dynamic Simulation And Driving Mechanism Of Spatial-temporal Pattern Of Gross Primary Productivity In Zoige Alpine Wetland

Wetland is an important type of global ecosystem,and its dynamic change of carbon budget plays an important role in the global carbon balance.As the largest plateau peat swamp distribution area in the world,the Zoige alpine wetland is very sensitive to climate change.Therefore,quantitative study on the spatial-temporal dynamics and driving mechanism of the gross primary productivity(GPP)under the context of global climate change in the Zoige alpine wetland is of great significance for the alpine wetland to cope with climate change and the conservation and restoration of the alpine wetland.The Zoige alpine wetland is taken as the research object in this paper,and the research method is the vegetation photosynthesis model(VPM).Based on the GPP data of two eddy covariance(EC)flux observation stations in the Zoige alpine wetland,using,two vorticity correlations(eddy correlation)were studied in the Zoige alpine wetland,the VPM model is parameterized,corrected and validated on the point scale.The validated model is used to simulate the dynamic changes of GPP in the Zoige alpine wetland during 2000～2016.The effects of long-term climate change and extreme drought on GPP in alpine wetland were discussed.The modeling results were compared with the experimental data of extreme climate control.On this basis,the key variables of the VPM model are extrapolated on the regional scale,and the GPP of the whole Zoige alpine wetland is simulated on the regional scale by using the VPM model.The spatial-temporal distribution pattern and driving mechanism of the GPP in the Zoige alpine wetland are analyzed and clarified.The main results are as follows:(1)The simulation results of VPM model can explain the change of GPP more than 76%during the growing season of Zoige alpine wetland.The verified model can be used to simulate the dynamic GPP of alpine wetland ecosystem.(2)From 2000 to 2016,the point scale GPP of Zoige alpine wetland showed an increasing trend,which was the same as the interannual variation trend of air temperature(Ta)and photosynthetically active radiation(PAR).TA,PAR and precipitation(PRE)are the main environmental factors affecting the change of GPP.With the decrease of precipitation,the GPP of Zoige alpine wetland also decreased.The results of model and control experiment showed that extreme drought significantly reduced the GPP of Zoige alpine wetland(P < 0.05).(3)The regional scale GPP of Zoige alpine wetland showed a regional distribution pattern of lower in the west and south area,higher in the middle area,and a slightly increased interannual variation trend in 2000 ～ 2014.PAR and Ta are the most important factors affecting the regional GPP variation.