Analysis Of Vegetation Cover Change And Its Response To Climatic Factors In Shanxi Province From 1986 To 2015

In recent years,the climate in Shanxi province has developed toward the direction of warming and drying,this change has triggered a series of ecological and environmental problems and has become one of the key issues that need to be resolved.Vegetation regulates energy exchange,carbon cycle,and regional climate change in ecosystems through photosynthesis,surface reflectance,and roughness.Understanding the relationship between spatial and temporal dynamic changes of vegetation and climatic factors and climate change can reveal the mutual response mechanism between vegetation change and climate change,and can also predict the impact of small climate changes on vegetation.This article uses the VIPPHEN_NDVI product data from 1986 to 1999 in Shanxi Province and the MODIS NDVI product data from 2000 to 2015 based on the trend analysis method,Mann-Kendall(MK)trend significance test method and Pettitt test method at R 3.3.3 and ArcGIS 10.3.The analysis of the dynamic trend of vegetation in Shanxi Province in the past 30 years,the significance of the change,and the year in which there may be mutations reveal the temporal and spatial variation of vegetation in Shanxi Province in the past 30 years.In addition,six types of climatic factors including annual precipitation pre,average annual temperature Tmean,annual maximum temperature Tmax,annual minimum temperature Tmin,annual potential evapotranspiration ETp,and leaf area index LAI at 16 sites in Shanxi Province from 1986 to 2015 were used to analyze the temporal and spatial dynamics of climate change in Shanxi Province in the past 30 years.Finally,the correlation analysis was used to analyze the relationship between vegetation changes and the six climatic factors and climate changes,and the vegetation and climate data were modeled using a stepwise linear regression method to simulate the climate change of vegetation.The research results mainly include:(1)In 1986-1999,there was no significant change in vegetation in 57.44%of the province,33.15%of the area's vegetation increased significantly,and 9.42%of the area's vegetation decreased significantly.Among them,the increase of vegetation was mainly occurred in 1993 and 1994.In the year,the events that promote vegetation reduction mainly occurred in 1991 and 1992;in 2000-2015,there was no significant change in vegetation in 77.87%of regions in Shanxi Province,21.92%of the region's vegetation increased significantly,and 0.2%of the region's vegetation significantly decreased.The events that promote vegetation increase mainly occurred in 2004,and the events that promote vegetation reduction mainly occurred in 2010.(2)In the 30 years from 1986 to 2015,the minimum temperature and evapotranspiration of Shanxi Province have basically all increased.Between 1986 and 1999,except for the decrease of rainfall in Yuncheng,Linyi,and the west of Luliang,the rainfall in other regions showed an upward trend.During the period from 1986 to 1999,except for the increase of the annual average temperature in the small areas of southern Yuncheng and the eastern part of central Jincheng,the average annual temperature in other regions showed a downward trend.During the period from 2000 to 2015,the annual average temperature of Shanxi Province showed an upward trend.During the period from 1986 to 1999,the maximum temperature in almost the entire city of Datong and Shuozhou showed a decreasing trend.During the period from 2000 to 2015,the maximum temperature in the north of Datong decreased significantly,the maximum temperature in the east of Yuncheng,the middle of Linfen,and the south of Luliang also showed a downward trend.During the period from 1986 to 1999,in the northern part of Shanxi Province,including Datong City,most of Shuozhou,eastern Xinzhou,and most of Yangquan,the leaf area index showed a downward trend,while the rest of the area showed an upward trend,and the period from 2000 to 2015 At the junction of Luliang,Jinzhong,and Taiyuan,the leaf area index of the narrow strips showed a downward trend.Central and Eastern Changzhi,Jincheng,The leaf area index in the eastern part of Linyi also showed a downward trend.(3)During the period from 1986 to 2015,the cumulative value of vegetation index and climatic factors were positively correlated,and the correlation coefficient was significant at 0.01 level.From 1986 to 1999,the correlation between the cumulative value of vegetation index,leaf area index,and minimum temperature was the highest;from 2000 to 2015,the cumulative value of vegetation index had the highest correlation with leaf area index and precipitation.(4)The Range values of vegetation changes in the 30 years from 1986 to 2015 are all significantly related to the variation of climate factors,Range,and the correlation coefficients are all significant at the level of 0.01.The variation of vegetation and Range and all climatic factors during the 14 years of 1986-1999.The values of Range are positively correlated,and have the highest correlation with the annual average temperature change;during the 16-year period from 2000 to 2015,the vegetation change value Range has a negative correlation with the change of all climatic factors,Range,and changes with the leaf area index.The Range and the lowest temperature change Range have the highest correlation.(5)The stepwise linear regression results of cumulative vegetation index and climatic factors from 1986 to 2015 show that all climatic factors have significant effects on the change of vegetation index.Using precipitation and temperature instead of climatic factors to model the cumulative vegetation index,it was found that for every 100 mm of precipitation,the impact on vegetation from 2000 to 2015 was higher than that of 1986-1999;but for every 1? change in temperature,for 1986-1999 The vegetation impact is higher than 2000-2015;if the precipitation and temperature change synchronously,it will have a greater impact on the vegetation change from 2000 to 2015.