GPP Simulation Of Grassland And Farmland Ecosystem In Xilinhot

In China the city of Xilinhot is located in the middle of the Inner Mongolia Autonomous Region.The regional ecological environment is fragile.It is an important farming area in northern my country,and the grassland reclamation is a local main land use change expression.Research the difference in the response mechanism between the local grassland and the farmland ecosystem on climate and environmental changes such as,the carbon source/saving status and potential of local ecosystems,which helps to predict the change in carbon density of regional ecosystems.Furtheronre,research subsequent land use regarding the ecological effects and sustainable development of the region provides scientific reference and theoretical support.This study passed the MODIS data and flux data,using the VPM and VI model at the site scale to simulate the changes of the farmland and the farmland ecosystem GPP（Gross primary productivity）,obtain the localization parameters of the model,applying the results of the VPM model to Xilinhot,obtained the city Changes in GPP Spatial Changes in Seeds and Farmland Ecosystems.The main research conclusions of this paper are as follows:（1）There is a significant difference in the natural environment of the grassland and farmland ecosystem.In addition to relative humidity,other environmental factors can reflect seasonal characteristics.The difference between different ecosystems is not significant,but the total amount of GPP in the farmland ecosystem is significantly higher than the grassland ecosystem.Using S-G filtering,can filter out the noise affecting the remote sensing data,the smoothing remote sensing data can better reflect the characteristics of different vegetation at different seasons.（2）Remote sensing and flux data were used to retrieve model parameters,and the parameters of VI and VPM models were localized in the study area.The R² values of VI model were 0.79 and 0.68 for grassland and farmland ecosystems,and the R² values of VPM model were 0.88 and 0.92 for grassland and farmland ecosystems,respectively.The accuracy of VPM model was higher than that of VI model.（3）Through the analysis of the model input parameters,it is found that the empirical parameters are not the main factors affecting the accuracy of the VPM model;The denoising of remote sensing parameters can improve the simulation accuracy of the model.The GPP of the ecosystem is regulated by a variety of factors.The GPP is positively correlated with the temperature between the lowest and highest photosynthetic temperatures of vegetation.Except relative humidity,water factors（VPD,rainfall）are directly proportional to GPP.There was a significant positive correlation between PAR and GPP（P<0.05）;Vegetation type is also an important factor affecting GPP.The relationship between GPP and remote sensing index was significant.（4）The spatial distribution of GPP in the whole growing season in Xilinhot showed a high trend in the east and a low trend in the north.Due to the obvious spatial characteristics of the annual average temperature and rainfall in Xilinhot,hydrothermal conditions were one of the reasons for this phenomenon.The average daily value of GPP in the eastern region during the growing season is between 7～9 g C·m^-2·d^-1,while that in other regions is between 5～7 g C·m^-2·d^-1.The overall spatial distribution pattern of GPP in Xilinhot in 2012 and 2013 was similar,but the monthly mean value of GPP in 2013 was slightly lower than that in 2012,which might be caused by drought.