A Study On The Dynamics Of Typical Grassland Vegetation In The Eastern Mongolian Plateau

The rational use of grassland resources is the basis for the sustainable development of grassland livestock breeding.The grasslands of Inner Mongolia Autonomous Region and Mongolia belong to the same Mongolian plateau region and are relatively rich in grassland resources.However,for a long time,the grassland ecosystem has deteriorated under the combined effect of natural and human factors.Therefore,it is important to study the degradation of grassland in Mongolian plateau region and clarify its driving factors for the sustainable development of grassland animal husbandry.The study area,Sukhbaatar province of Mongolia and Xilin Gol league of Inner Mongolia Autonomous Region of China(Sunite Left Banner,Abaga Banner and Xilinhot City),are adjacent border areas of China and Mongolia.The two regions have interlinked native vegetation zones,almost equal study areas,similar climate types,and sensitive climates with fragile ecosystems.So far,although there have been a large number of macroscopic studies,there are few about multi-scale studies of remote sensing data combined with ground data especially comparative analyses of vegetation changes in transboundary areas,Therefore,in this paper,we will use remote sensing data(MODIS NDVI data,Landsat TM data)and field survey plant community sample data in the selected study area,and apply the methods of image dichotomy,plant community determination,linear trend method and correlation analysis to conduct comparative analysis of vegetation change in the study area from macroscopic areas of MODIS NDVI,mesoscopic areas of Landsat TM data,microscopic areas of community sample zones,etc.On the basis of the comparative analysis of vegetation change in the study area at different regional scales,we further explored the factors influencing vegetation change in the study area.The main conclusions of the study are as follows:(1)On the macroscopic scale,During 2001-2018 vegetation NDVI in Sukhbaatar province of Mongolia in the study area and Xilin Gol league(Sunite Left Banner,Abaga Banner and Xilinhot City)in Inner Mongolia Autonomous Region of China during the growing season(April-October)showed the same the same trend with an overall slow growth trend.However,the NDVI growth rate of vegetation in Sukhbaatar Province of Mongolia in the study area(0.0027/18a)was larger than that in Xilin Gol League area of Inner Mongolia Autonomous Region of China(0.0014/18a).(2)On the medium scale,by comparing the vegetation cover of Mongolian Naran Sumu and Chinese Narenbolag Sumu in the same period,it was found that both Mongolian Naran Sumu and Inner Mongolia Narenbolag Sumu were dominated by medium and high vegetation cover in 1989,and the vegetation cover of Narenbolag Sumu turned to be dominated by low and medium by 2016.In contrast,the vegetation cover of Mongolian Naran Sumu was larger than that of our Narenbolag Sumu,and the change of vegetation cover of Narenbolag Sumu fluctuated more obviously.(3)On Microscopic scale,the analysis of community plant composition,importance values,community quantitative characteristics and community β-diversity index by comparing the sample plot data in the study area revealed that the importance values,community quantitative characteristics and inter-community similarity of the native community building species were higher in Naran Sumu than in Narenbolag Sumu.The native species in Naran Sumu plant community was significantly higher,while the proportion of perennials was lower and the proportion of annuals was significantly higher in Narenbolag Sumu.(4)The correlation coefficients of vegetation NDVI with precipitation and air temperature were 0.89(P>0.01)and-0.67(P>0.05)for Sukhbaatar province,Mongolia,during 2001-2018,while 0.84(P>0.01)and-0.51(P>0.05)for Xilin Gol league in China,respectively.It can be seen that precipitation has a promoting effect on vegetation cover,However,the increase or decrease of temperature can inhibit or promote the growth and development of vegetation..(5)The changes in the number of livestock and livestock structure in Narenbaolag Sumu,Inner Mongolia Autonomous Region,corresponded to the changes in the stage change process of the livestock operation mode in this Sumu.It can be seen that the changes in the number of livestock and herd structure are influenced not only by natural factors but also by grazing methods and market prices,and grazing methods indirectly affect the number and structure of livestock,which in turn affects vegetation changes.(6)Vegetation changes in the study area are influenced not only by natural factors but also by livestock-related development,changes in grazing practices,and market economy development.However,under similar natural conditions such as precipitation,pasture vegetation communities are more influenced by pasture use patterns and intensity of use.