| This paper takes the MODIS long-term series of vegetation in Guizhou Province from 2000 to 2017 for 18 consecutive years and monthly average temperature,precipitation,and relative humidity data as the research object,combined with geological and geomorphic data in the study area,using trend analysis,correlation analysis,Hurst index,regression analysis,residual analysis and other methods,in the study,we obtained the spatio-temporal changes of vegetation coverage and vegetation coverage types in Guizhou Province from 2000 to 2017,and their response to different geological and geomorphic types,to explore the correlation and lag correlation of climate change,the main research results are as follows:(1)From 2000 to 2017,the vegetation coverage in Guizhou Province showed a significant increase trend,with a growth rate of 0.004 yr/a,which was the highest in summer and higher in autumn than in spring;The vegetation cover showed a spatial distribution of south-high,north-low,east-high and west-low,and the areas of improvement and degradation accounted for 94.97% and 5.03% of the total area of Guizhou Province,respectively.The vegetation in the north and southwest of Guizhou Province was more sustainable and the middle was worse,but the overall vegetation was anti-sustainable.The types of vegetation cover were mainly shrub and arable land,the grassland area continued to decrease,the area change rate of forest land and grassland was the largest,and the shrub was the smallest.In 2000-2017,about 21.33% of the area in Guizhou Province changed its vegetation types,and the change areas were mainly concentrated in the west and north.There were differences in NDVI values under different geological and geomorphological backgrounds,vegetation growth in the clastic rock areas was better than in other areas,the average NDVI and NDVI change trends increase with the elevation and fluctuation.From 2000 to 2017,the rainfall in Guizhou Province was unevenly distributed throughout the year.Generally showing the spatial distribution characteristics of high in the south and low in the north,and high in the east and low in the west.Against the backdrop of global warming and humidification,most areas of Guizhou Province also showed a trend of increasing temperature and increasing precipitation,but the relative humidity was decreasing.(2)The inter-annual change had a strong correlation between NDVI and air temperature,the correlation with precipitation was not significant,and had a strong negative correlation with relative humidity;spring and winter temperatures greatly promoted vegetation growth,vegetation growth is mainly affected by precipitation and relative humidity changes in autumn.Under different geological and geomorphological backgrounds,the correlation between NDVI and various climatic factors was consistent with the correlation characteristics of the whole region.The correlation coefficient with the temperature of the same year was still the highest,followed by precipitation,and finally the relative humidity;the hysteresis of the relative humidity is the strongest,followed by precipitation,and there is no hysteresis correlation with temperature.Air temperature,precipitation,and relative humidity in the previous year had the most significant effects on vegetation growth in the limestone hills,limestone hills,and dolomite hills.The correlation coefficient of forest land in large rolling hills and temperature was greater than that in hilly and small rolling hills;the correlation coefficient of shrubs and grasslands in hilly areas was relatively small,and the cultivated land was just the opposite;The growth of various vegetation types in hills and small rolling hills were greatly affected by the precipitation in the previous year.The forest land(coniferous forest,broad-leaved forest,and mixed forest)in the large rolling hills was mainly affected by the relative humidity in the previous year,while the shrubs and cultivated land in the small rolling hills were affected in hilly areas,other vegetation types except coniferous forests were less affected by relative humidity.(3)The accuracy of vegetation-climate multivariate linear and nonlinear fitting increases with the number of fittings,and the overall nonlinear fitting precision was greater than that of multivariate linear.Vegetation-climate lag fitting accuracy was greater than vegetation-climate fitting accuracy,and the climate factor variable in the western region had a stronger ability to explain vegetation NDVI.Vegetation-climatic multivariate nonlinear fitting accuracy in clastic rock areas was greater than in dolomite and limestone areas.The clastic rock mountainous climate had the strongest ability to explain vegetation changes;other factors besides climate had effects and effects on vegetation growth can not be ignored.(4)The enhancement of vegetation coverage in Guizhou Province was dominated by human activities,supplemented by climate change factors.The relative contribution rate of human activities and climate change to vegetation NDVI change in Guizhou Province was 76% and 24% respectively,and the relative contribution rate had spatial differences.The climate contribution rate was mainly concentrated between 0 and 50%,indicating that the positive effect of climate change on vegetation growth was not the largest,and the large undulating limestone mountains were most affected by human activities. |
PDF Full Text Request