Response Of Forest Vegetation Dynamic Changes To Climate In Hanshan Secondary Forest Area

We studied the dynamic change characteristics of forest vegetation in Hanshan secondary forest area.Based on MODIS NDVI remote sensing data and climate data from 2000 to 2015,MVC maximum synthesis,mean value method,trend analysis method,partial correlation analysis and other methods were adopted in this paper.We explore the dynamic change of vegetation and the response of climate in Hanshan secondary forest area.We fully understand the impact of climate change on the dynamics of local vegetation.The study will be provide a scientific basis for the use and conservation of local natural resources.The results showed that:1.NDVI increased in spring,summer and growing season in Hanshan secondary forest area.NDVI showed a downward trend in autumn,with a rate of 0.0004/a.The mean method was used to calculate the average NDVI in spring,summer,autumn and growing seasons from 2000 to 2015.The study found that NDVI was the highest in summer and the lowest in spring.The average NDVI value of season showed the largest NDVI of vegetation in the northeast region.According to the variation amplitude of NDVI,the spatial variation trend of NDVI is divided into 7 grades.The change was mainly mild,and the area of improvement was significantly greater than that of degradation.Therefore,the overall vegetation status is stable in Hanshan secondary forest area and it shows a trend of improvement in some areas.2.Precipitation was on the rise in Hanshan secondary forest area.The temperature showed a downward trend.Compared with the variation trend of seasonal average precipitation and seasonal average temperature.The precipitation fluctuation was more obvious and the variability was larger.From the perspective of time,it was found that the seasonal average NDVI of the four seasons was significantly correlated with the precipitation in the same period.In the partial correlation study,the partial correlation coefficient between precipitation and NDVI was larger than that between temperature and NDVI in spring,summer and growing season.It indicated that precipitation was the main factor affecting vegetation growth.The effect of temperature on vegetation growth was most obvious in autumn.The temperature in other time periods had a certain influence on the vegetation growth,but it’s not obvious.3.The correlation coefficient and partial correlation coefficient between seasonal NDVI and climatic factors were analyzed in detail.The correlation coefficients between NDVI and meteorological factors in the first two periods,the early period and the corresponding period were calculated.I found that the time lag of NDVI response to climate change in summer and growing season.Finally,it was concluded that the vegetation growth had a certain lag effect on the response of precipitation in May,July and August.In the study of partial correlation,the response of vegetation growth had lag effect to early precipitation in May,while the lag effect of temperature was not obvious on vegetation growth.