Temporal And Spatial Variations And Influencing Factors Of Vegetation NDVI In The Northern Slope Of Tianshan Mountains,Xinjiang

The Normal Difference Vegetation Index(NDVI)is usually used to feed back the Vegetation coverage on the surface.According to climate factors and Vegetation Index,it can reveal the impact of local climate change on Vegetation coverage.Therefore,this article mainly using the cloud data provided by the geographical spatial data,information,climate data merging of possession,use of extraction and analysis,the maximum synthesis,monadic regression trend analysis,correlation analysis,analysis of the north slope of Tianshan Mountainous in Xinjiang nearly 18 years of annual,monthly,and during different seasons,NDVI changes,thus the relationship between time and climate factors.The analysis of the change of NDVI and its response to climate factors on the north slope of Tianshan Mountainous in Xinjiang will be of great significance to the overall characteristics of land use in this area as well as the regional and global climate and environmental changes.The results show that:(1)in terms of time: during the period from 2000 to 2017,the corresponding NDVI value of the north slope of Tianshan Mountainous in Xinjiang was between0.27 and 0.3,and showed an upward trend.The corresponding monthly average NDVI basically increased after April every year,peaked in July,and then decreased,so it has the characteristic of single peak.It can be found that in different seasons,the vegetation index of the north slope of Tianshan Mountainous in Xinjiang basically rose.Spatial: the vegetation coverage of the north slope of Tianshan Mountainous in Xinjiang is characterized by low eastern,high western,low northern and high southern.At the same time,there is a significant spatial difference between the annual average NDVI value and the growth season NDVI value,which mainly shows that the vegetation coverage increases in the central region,while the rest of the vegetation decreases.(2)in the past years of development,the average precipitation and the average temperature of the north slope of Tianshan Mountainous in Xinjiang have shown a rising trend,and also increased--decreased--increased as a specific manifestation.If analyzed from the perspective of space,the southern mountainous area of the Northern Slope of Tianshan Mountainous in Xinjiang is characterized by high precipitation and low temperature,while the northern plain is characterized by high temperature and little rainfall.(3)NDVI index is greatly affected by temperature and rainfall.Since the growth of vegetation is affected by precipitation and temperature,the relationship between vegetation and temperature is relatively close in spring and precipitation iseven closer in summer.The effect of precipitation on vegetation coverage is usually greater than that of temperature.(4)during the growth period from may to September,the relationship between NDVI value of vegetation and precipitation and temperature is hysteresis.(5)according to the superposition analysis of NDVI on the north slope of Tianshan Mountain in Xinjiang according to different altitude,the elevation of NDVI is in the range of 500 ? 2500 m,and NDVI gradually increases with the elevation.If the altitude is between 1500 m and 2500 m,the value of NDVI is relatively high,basically around 0.49.At altitudes below 200 meters,the NDVI index shows a downward trend.(6)according to the superimposed analysis of NDVI on the north slope of Tianshan Mountainous in Xinjiang,the highest NDVI value of paddy soil was 0.74,and the lowest average NDVI value of stony soil was 0.09.(7)from the relationship between land use type change and NDVI change,it can be concluded that the area change of paddy fields,woodland,grassland and other types is basically inversely proportional to NDVI.The larger the area,the lower the NDVI value is.It can also be seen that the NDVI value of paddy fields is higher than that of other LUCC types.The dry land area is proportional to the NDVI value,and the NDVI value increases with the increase of the area.In 2000,2005 and 2010,the area of shrubbery and sparse woodland was inversely proportional to NDVI,but with the decrease of area,the value of NDVI was higher,which was directly proportional to that in 2015.(8)according to the relationship between population change and NDVI change,the areas with positive correlation between NDVI and population accounted for40.61% of the total area,22.50% with positive correlation(p<0.01),and 18.11%without(p<0.05).Among them,43.53% were negatively correlated,27.71% were significantly negatively correlated,and the remaining 15.82% were not significantly negatively correlated.Irrelevant areas accounted for 15.86% of the total area.(9)if the relationship between GDP and NDVI is analyzed,it can be found that the correlation between NDVI value and population is positively correlated,accounting for 38.67% in this region,26.42% of which are significantly positively correlated(p<0.01),and 12.25% of which are not significantly positively correlated(p<0.05).The negative correlation area accounted for 43.49%,the significant correlation area accounted for 23.21%,and the rest was 20.28%.Uncorrelated areas accounted for 17.84% of the total area.