| In the process of the development of human history,land resource is an important basic material guarantee,and the change of land use directly presents the result of the interaction between human activities and nature.The overdevelopment and abuse of land resource has directly led to the destruction and deterioration of ecological environment in different degrees.Qinling Mountain is an important ecological security barrier for China,and it is the dividing line of geographical and climatic classification between North and South provinces.It has complex terrain,mountains and diverse ecosystems.However,excessive cultivated land reclamation,mining,deforestation of natural trees,rapid expansion of surrounding cities,a large number of illegal villas in the northern foot of Qinling Mountains and so on.Due to the unrestrained exploitation and occupation of resources by human beings,the ecological environment in this area is facing threats.In recent years,the Party Central Committee and the State Council have attached great importance to the protection of ecological environment in Qinling Mountains,and adopted a series of ecological renovation and protection measures.Taking Qinling Mountains as the research object,based on the statistical data of land use in 1980,2000 and 2018,this paper studies and analyzes the evolution characteristics of historical spatial-temporal pattern of land use change in different periods of time in Qinling Mountains by using land use dynamic degree model,regional difference of land use change and land use transfer matrix.Then,the eco-environmental quality index of Qinling Mountains is determined according to the ecosystem service value,and the eco-environmental situation is quantified in time and space by using the geostatistics principle.The cold and hot spot pattern of eco-environmental quality change in Qinling Mountains is analyzed,and the ecological contribution of land use change types is calculated.Finally,the formation mechanism of spatial differentiation of land use eco-environmental effects in Qinling Mountains was identified by using the geographic detector model.According to the above research results,the corresponding suggestions are put forward to provide the corresponding scientific basis for the improvement of ecological environment in Qinling Mountains.The results show that:(1)the current situation of land use in Qinling Mountains is as follows:forest land(36.74%)>grassland(35.03%)>cultivated land(25.63%)>urban and rural construction(1.89%)>water area(0.67%)>unused land(0.05%).Woodland is concentrated in the high altitude areas of the central and western part of the study area,grassland is distributed in the surrounding zhonghaiba mountainous area,cultivated land and urban and rural construction land are distributed in the northern Guanzhong Plain and the southern Hanjiang Valley,cultivated land is surrounded by urban and rural construction land,water area is mainly used by a small number of reservoirs in the Hanjiang River,Weihe River Basin and southern mountainous area,and unused land is distributed in the high altitude area Along the mountains and rivers.(2)From 1980 to 2018,the land use changes in Qinling Mountains are as follows:the total area of cultivated land continues to decline year by year,the total area of urban and rural construction land has increased significantly,the water area has also increased,and the proportion of other types of land has little change.From 1980 to 2000,the proportion of relative change of cultivated land in Linwei district was the largest,that of woodland was Huazhou District,that of grassland and unused land was Linwei District,that of water area was Huayin City,that of urban and rural construction land was Huayin City,that of cultivated land was Liuba County,that of woodland and grassland was Qishan County,that of water area was Weibin District,that of urban and rural construction land was Zhashui County,and that of unused land was not It is Linwei district that is used.From 1980 to 2000,the main types of land use change transfer were grassland cultivated land and construction land occupied cultivated land;from 2001 to 2018,the main types of land use change transfer were cultivated land abandoned to grassland and construction land occupied cultivated land.(3)In 1980,2000 and 2018,the total value of ecosystem services in Qinling Mountains reached 87.453 billion yuan,87.290 billion yuan and 86.923 billion yuan,respectively,showing a downward trend.From 1980 to 2018,the eco-environmental quality index of Qinling region declined as a whole,showing a trend of first rising and then declining.The high and high quality areas of ecological environment are mainly distributed in the Midwest of the study area,the medium quality areas are mainly distributed in the southeast of the study area,and the urban plain parts of Xi’an City,Baoji City in the northern foot of Qinling Mountains and Hanzhong City in the southern foot of Qinling Mountains are mainly low-quality and low-quality areas.(4)From 1980 to 2000,the eco-environmental quality improvement areas in Qinling Mountains were mainly distributed in three hot spots:the north of Huayin City and Tongguan County,the south of Hanbin District and the north of Shangnan County.The ecological environment deterioration areas are mainly distributed in five cold spots:the west of Zhouzhi County,the north of Chang’an District,the east of Huazhou District,the south of Shangzhou District and the east of Shanyang County.From 2001 to 2018,Qinling eco-environmental quality improvement areas are mainly distributed in five hot spots:the south of Chang’an District and Weiyi District,the north of Huayin City,the southwest of Tongguan County,the south of Shangzhou District and the north of Zhouzhi County.The ecological environment deterioration areas are mainly distributed in five cold spot areas:the junction of Eastern Jintai district and Weibin District,the north of Chang’an District and Weiyi District,the middle of Linwei District,the southeast of Mianxian County,the middle of Chenggu County and the southeast of Chenggu County.(5)From 1980 to 2000,among the land types that caused the improvement of eco-environmental quality,the largest contribution rate was the conversion of dry land into high coverage grassland,rivers and reservoirs;the main types of land changes that led to the deterioration of eco-environmental quality were the conversion of woodland into shrubbery,the conversion of high coverage grassland and medium coverage grassland into dry land.From 2001 to 2018,the main types of land use change causing the improvement of eco-environmental quality are the transformation of dry land into high coverage grassland;the transformation of dry land into other construction land and rural residential areas,and the transformation of high coverage grassland into dry land are the main types of change causing the deterioration of eco-environmental quality.(6)The influencing factors of the spatial differentiation of land use ecological environment in Qinling Mountains were ranked as follows:X2 average altitude>X1topographic relief>X3 annual average temperature>X4 annual average precipitation>X7population density>X8 average GDP>X5 land use diversity>X6 land use degree.There are two ways of interaction:nonlinear enhancement and two factor enhancement.The interaction of X2 average altitude and X7 population density is the strongest.(7)The results of detecting the risk area of spatial differentiation of eco-environmental quality are as follows:the area with slope of 36.72°to 73.15°and altitude of 2392m to 3747m,the area with annual average temperature of 5℃to 8℃,the area with annual precipitation of1252mm to 1287mm,the area with population density of 13.77 people/km~2 to 66.29 people/km~2,and the average GDP is 460500 yuan/km~2–Within 3.134 million yuan/km~2,the average value of eco-environmental quality index is the highest,which is the dominant area of Qinling eco-environmental quality index level. |
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