Contributions Of Climate Change And Human To Vegetation Dynamics Of Loess Plateau From 1982 To 2015

As an important part of terrestrial ecosystem,the vegetation is sensitive to climate change,changes its growth has obvious indication on global climate change.Through long-term monitoring of vegetation coverage changes,not only can reflect the regional ecological environment and climate change,and to provide scientific decision support for the regional ecological management.As one of the ecological sensitive area in China,the loess plateau ecological problems such as soil erosion,soil desertification is very outstanding,in the area of vegetation coverage change for long time monitoring is of great importance to ecological significance.This article through to 1982-2015 on the loess plateau GIMMS NDVI 3g time series data set and 117 ground meteorological sites around 1981-2015 monthly precipitation and monthly mean air temperature meteorological data processing and analysis,the following main conclusions:(1)The vegetation of the loess plateau is covered in space from the semi-humid region of the southeast to the arid region of the northwest arid the area of the arid region is low,with distinct regional variations.By trend analysis and wave characteristics analysis of the loess plateau vegetation change in the past 34 years showed increased trend,slow wave in the surrounding vegetation spatial volatility of yulin city is the largest.(2)Loess plateau in 1982-2015 annual total precipitation shows ascendant trend,but trends were not significant in the space,and the annual average temperature increases significantly,in the northeast of shanxi datong,shuozhou region,the temperature rise of the trend is most obvious.(3)Through the calculation of the loess plateau in April to October growth season of NDVI and climate factors(precipitation,temperature)correlation coefficient and partial correlation coefficient,the multiple correlation coefficient,results show that the partial correlation between NDVI and climate factor than correlation and correlation.It shows that the vegetation growth of loess plateau is affected by precipitation and temperature,and the water heat conditions of precipitation and temperature are obviously unbalanced.(4)Using the method of BP neural network improved residual trend in the loess plateau vegetation change to study the contribution of climate and human activity,and combination of the loess plateau region Chinese forestry statistical yearbook from 2002 to 2014 in the afforestation area of statistics,the trend of night lighting in the DMSP data from 1999-2013,respectively rise to changes in vegetation cover area and vegetation change area verified.Results show that the loess plateau vegetation change in the more significant the influence of human activity,the climate in the local area to improve the growth of vegetation played a role.The effective implementation of ecological projects such as returning farmland to forest is the important reason for the restoration of vegetation.The destruction of vegetation is mainly due to the expansion of the city,which conforms to the spatial distribution characteristics of human activities in the loess plateau.