Study On The Change And Driving Factors Of Forest And Grasslands Cover In Shaanxi Province

Forest and grasslands cover is an important factor affecting land quality and a key factor in the prevention and control of natural disasters such as soil and water loss.Since the introduction of Grain for Green Project,the quality of ecological environment and the living standards of farmers in Shaanxi Province have been significantly improved,and then the industrial structure of Shaanxi Province has been optimized and the economy has developed rapidly.The No.1 document of the Central Committee of the people's Republic of China in2014 clearly pointed out that China will launch a new round of Grain for Green Project.Therefore,by understanding the influencing factors of forest and grasslands cover in recent years and analyzing the characteristics of forest and grass land distribution in the future under the current conditions,It is of great significance to the improvement of relevant land policies and the adjustment of economic structure in the future.Based on the socio-economic and physical geographical factors at the county level,this paper discussed the driving force of forest and grasslands cover change and forecasted the trend of forest and grass cover change.Taking Shaanxi Province as an example,this paper analyzed the regional difference and change direction of forest and grasslands in Shaanxi Province from 1990 to 2015.Through spatial autocorrelation analysis,it was verified that the distribution of forest and grassland in Shaanxi Province had a strong spatial correlation.Then,by using the spatial Dubin model,the fitting results of the influencing factors were divided into direct effect,indirect effect and total effect,and the influencing factors affecting the change of forest and grassland area were analyzed.Finally,Then using FLUS model simulated the changes of forest and grassland in 2020,2025 and 2030,combined with the socio-economic driving factors obtained by spatial Durbin model and natural geographical factors.The conclusions are as follows:(1)The coverage area of forest and grass land in Shaanxi Province is stable at first and then rises,cultivated land is the land use type which is mainly transformed into forest and grassland.The change of forest and grassland in Shaanxi Province was stable from 1990 to2000.From 2000 to 2010,the total area of forest and grassland increased obviously under the background of Grain for Green Project and Natural Forest Conservation Project.The increase of forest and grassland area in Shaanxi Province slowed down slightly from 2010 to2015.(2)The forest and grass land in Shaanxi Province is distributed in space,and the spatial correlation is strong.The distribution range of forest and grass land in Shaanxi Province is relatively concentrated,large areas of forest and grass land are distributed in southern Shaanxi and Yan'an area of northern Shaanxi,small pieces of fine forest land are distributed in Yulin area of northern Shaanxi,and cultivated land is the main land in Guanzhong Plain area.There are fewer forests and grasslands.Through the global and local spatial autocorrelation test,the global Moran's I index of forest and grassland area distribution at county level in Shaanxi Province in 1990,2000,2010 and 2015 was 0.48,0.49,0.50 and0.52,respectively,which proved that there was a strong correlation.In the local Moran's I exponential scatter plot,The high-high concentration areas are mainly concentrated in the Yan'an area of northern Shaanxi and most areas of Shangluo and Ankang in southern Shaanxi,as well as a small part of Hanzhong,and the low-low concentration areas are mainly concentrated in the Guanzhong Plain area east of Baoji City.The low-high areas are mainly distributed at the intersection of Hanzhong and Ankang in southern Shaanxi(3)The industrial upgrading index,land average GDP,population density,the ratio of fiscal revenue and subsidy of Grain for Green Project have significant effects on forest and grassland.The spatial Dobbin model is divided into direct effect and indirect effect.The industrial upgrading index,land average GDP,population density,the ratio of fiscal revenue and subsidy of Grain for Green Project have a direct effect on the area of local forest and grassland.Among them,the land average GDP and population density have negative effects,and the land average GDP,population density,the ratio of fiscal revenue and subsidy of Grain for Green Project have indirect effects on the surrounding areas,among which the land average GDP has a negative effect.(4)According to the simulation results,the change form of forest and grass cover is mainly the transformation from non-forest and grass land to forest land in southern Shaanxi and from other land types to grassland in northern Shaanxi.The area of unchanged land in the province was 196724.52km~2,from non-forest and grass land to grassland,693.99 km~2,accounted for 0.34%of the total land area of the province,and 5053.68 km~2,from non-forest and grass land to forest land accounted for 2.45%of the total land area of the province.The conversion from woodland to grassland is 476.73 km~2,The transformation of 1395.99 km2,from forest land to non-forest and grass land accounted for 0.68%of the total land area of the province,and 760.41 km~2,from grassland to forest land accounted for 0.37%of the total land area of the province.The conversion from grassland to non-forest land accounts for831.06 km~2,of the total land in the province.The total area of forest and grassland increased by 3520.62 km~2,accounting for 1.71%of the total land area of the whole province.