| Vegetation is an important component of the geographical environment.It's growth and development are closely related to the intensity of human activities and the geographical environment which is closely related to the geological environment.After the analysis of previous studies,it can be found that scholars usually only consider factors such as terrain,geomorphology,climate,and human activities when analyzing the impacts of vegetation coverage,rarely considering the relationship between vegetation coverage and geological environment.It is difficult for such studies to comprehensively describe and analyze the causes and development trends of vegetation spatial distribution.This thesis considered the impacts of the topography,climate,human activities and so on,especially geological and environmental factors.Mianning County with complex geological background conditions was regarded as the research object,in order to explore the vegetation coverage and the spatial distribution pattern of geological environment.This thesis analyzed the background factors such as the geological structure,stratigraphic lithology and topography in Mianning County.Using the MODIS EVI 1km data from 2003 to 2018 and the temperature and precipitation data to discuss about the characteristics of the static spatial distribution of vegetation,the characteristics of interannual dynamic changes of vegetation coverage and the dynamic pattern changes of vegetation coverage in the study area.Then geographically weighted regression(GWR)model was used to explore the relationship between vegetation coverage and the spatial distribution of geological environment,and corresponding protection measures were proposed for vegetation coverage according to the degree the influence of different geological environments.The main research conclusions are as follows:(1)The vegetation coverage was high in the southeast and low in the northwest.There were obvious spatial differences in Mianning County.From 2003 to 2018,the vegetation coverage was dominated by high vegetation coverage and medium-high vegetation coverage.The overall trend and fluctuations were not significant.62.23% of the pixels of vegetation coverage showed an increasing trend,and 1.38% of the pixels showed a decreasing trend,and 36.39% of the region's vegetation status remained basically unchanged.According to the order of pixels,the standard deviations of vegetation cover changes in Mianning County from 2003 to 2018 was calculated.The results showed that the overall vegetation coverage of Mianning County presented the distribution characteristics of high in the northwest,low in the southwest and middle.At the same time,there were obvious regional differences in stability.Through the analysis of the changes of center of gravity,it can be found that the location of the center of gravity covered by middle-low vegetation,medium vegetation and middle-high vegetation was basically unchanged,and the high vegetation coverage and low vegetation coverage moved to southwest,northeast,southeast and southwest respectively.(2)GWR analysis of the spatial differentiation of vegetation coverage in Mianning County showed that geomorphology,climate and geological factors had a greater impact on the spatial distribution of vegetation coverage.Among the factors with greater influence were elevation,average annual precipitation,night light and tectonic Euclidean distance.The average estimated coefficients were 0.0602,0.0362,0.0115 and-0.0085.The effective interpretation area accounted for 77.20%,58.90%,56.10% and 53.40%.The areas with obvious elevation analysis effect were mainly distributed in Yele Township,Daqiao Town,Yihai Town,Caogu Township,Chengxiang Town and Lianhe Township,etc.The areas with obvious annual average precipitation analysis effect were mainly distributed in Wobao Township and Caogu townships and eastern areas of Yihai Town.The areas with obvious night light analysis effects were mainly distributed in the middle of Yihai Town and the east of Nanhe Township.And the areas with obvious structural Euclidean distance analysis effects were mainly distributed in Haha Township,central Hui'an Town,and eastern Chengxiang Town.And the west of Daqiao Town.The factors with less influence were the aspect(-0.0066),the geomorphic dimension(0.0038),the slope(-0.0024)and the average annual temperature(-0.0015).(3)Through exploring the relationship between spatial distribution of geological environment and vegetation coverage in Mianning County,vegetation protection measures were proposed based on the background of geological environment.Mianning County can be divided into 18 blocks according to watershed units and landform types.combining with the analysis of landform type,land use type,vegetation type,fault zone distance,stratigraphic lithology and climate and other factors in each block,three models of natural restoration and artificial ecological restoration under artificial intervention were proposed to protect vegetation. |
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