| Monitoring accurately the temporal and spatial changes in the above-ground biomass of desert-oasis ecosystems in the Ejina Banner can reflect the changes of the ecological environment wih the research area.Researching the temporal and spatial changes in the vegetation above-ground biomass response to groundwater depth and climate change,in order to provide scientific basis for ecosystem restoration and water allocation in Ejina region.Since the Ejina Banner implemented ecological water transport for more than a decade,the vegetation types in the study area have gradually increased,and the ecological environment has shown a good trend.Considering the good changes with the ecological environment in the study area,the ARCGIS,ENVI and EXCEL software tools were used to count the above-ground vegetation aboveground biomass,groundwater depth and meteorological data(temperature,rainfall and sunshine duration)for the Ejina Banner in the period from 2000 to 2015.Through analysis,the regression analysis method in the SPSS software tool was used to analyze and discuss the response to relationship among the above-ground biomass of the Ejina Banner,groundwater depth,and climate change from 2000 to 2015.The conclusions are as follows:(1)In the 16 years from 2000 to 2015,the aboveground biomass of the Ejina Banner shows an increasing trend as a whole.The above ground biomass data and NDVI data are used to establish a vegetation aboveground biomass estimation model.The results are three regression equations.For the best estimation model,R~2 is 0.776,and the overall average error coefficient between the measured and estimated values from 2000 to 2015 is 23.6%.The results of the study shows that the above-ground biomass of the Ejina Banner had an increasing trend from 2000 to 2015.The average annual above-ground vegetation biomass was 1.941×1012 g,the lowest value was 1.918×1012 g in 2002,and the highest value was 1.992×1012 g in 2015.(2)From the perspective of time,the average annual groundwater depth in Ejina Banner increased from 2000 to 2015,and the overall change trend showed three changes: Groundwater depth at the rate of 0.0139m/a from 2000 to 2010.Reduction;Groundwater depth increased from 0.004m/a in 2010-2014;Groundwater depth in 2014-2015 decreased by 0.14m/a.From a spatial point of view,the two observation wells with relatively shallow groundwater depth distribution in the Ejina Banner from 2000 to 2015 are No.13 and No.33,and the groundwater funnel is located at Susukozze(approximately 5km north)of Dubhai Sea(Well No.06).There was a positive correlation between above-ground biomass of vegetation and groundwater depth in Ejin Banner(R~2=0.222,F=3.996).The results showed that the correlation between groundwater depth and vegetation above-ground biomass was not significant.(3)During the 50 years since 1966-2015,the average annual temperature of the Ejina Banner showed an increasing trend,while annual rainfall and annual sunshine hours showed a decreasing trend.During the typical time years from 2000 to 2015,the annual average temperature and annual cumulative rainfall in the study area showed an increasing trend,which was conducive to vegetation growth,and the corresponding above-ground biomass was also increased,while the annual cumulative sunshine hours showed a decreasing trend.The correlation between annual mean temperature,annual accumulated temperature and vegetation aboveground biomass(R~2 =0.422,F=10.27?R~2=0.3819,F=8.649)was greater than the correlation between annual rainfall,annual sunshine hours and vegetation biomass(R~2=0.267,F=5.112?R~2=0.206,F=3.629).Therefore,the results indicate that the temperature is the main climatic factor that influences the aboveground biomass changes in the Ejina area on the interannual scale. |
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