Impact Of Temporal And Spatial Evolution Of Human Activity Intensity On The Trade-off Of Ecosystem Services And Gradient Difference

The impact of human activities on the trade-off of ecosystem services can’t be ignored.Since the reform and opening up,China’s economy has developed rapidly and the population has increased sharply.The increasing human activities have intensified the contradiction between the economic development,food security and ecological protection,and the ecological environment problems have become more and more prominent,which has a profound impact on the well-being of Chinese residents.Clarifying the characteristics of the trade-off of the ecosystem service under the intensity of human activities,to explore the effect of human activities on the ecological environment.It is conducive to providing theoretical support for the high-quality construction of ecological civilization in China at this stage.This paper took the Shaanxi province as the experiment area,based on population,GDP,land use,meteorology,soil,NDVI and other data,then,used ecosystem service evaluation model and root mean square deviation method,analyzed the differences of the gradient of ecosystem services and their trade-offs in Shaanxi Province under the different intensity of human activities in 1990 and 2018 quantitatively,and discussed the change rule and characteristics of ecosystem service trade-off caused by the temporal and spatial change of human activity intensity from 1990 to 2018.Analyzed the main reasons for the change of ecosystem service trade-off by root mean square deviation mapping,the conclusion are as followed:In 2018,the total economic output of Shaanxi Province was 60.45 times that of 1990,and the population density was 1.18 times that of 1990.At the same time,the land use intensity index of Shaanxi Province has increased,and the intensity index of human activities has increased from 0.475 to 0.545,In 2018,the temporal and spatial distribution pattern of human activity intensity in Shaanxi Province has changed from"high in Central South and low in Northwest China"in 1990 to"two areas and one point"markedly.Under the background of climate factors unchanged,From 1990 to 2018,carbon sequestration in Shaanxi Province has increased from 392.46 g C·m^-2·a^-1 to 529.62 g C·m^-2·a^-1,and soil conservation increased slightly;water production showed a small loss,Food supply decreased significantly,with a decrease of 115.52 kg·hm^-2·a^-1,from 223.88 mm·a^-1in 1990 to 221.35 mm·a^-1 in 2018.During this period,soil conservation and carbon sequestration have been improved in Qinba mountain and the central part of Northern Shaanxi Loess Plateau,while the food supply of Guanzhong Plain and some areas of Northern Shaanxi Loess Plateau has decreased.Water production services in some areas of Guanzhong plain have been improved greatly.From 1990 to 2018,the trade-off between services in Shaanxi Province generally intensified,and the trade-off between carbon sequestration and food supply increased most significantly.In 1990 and 2018,under different human activity intensity gradients,the change trends of carbon sequestration,soil conservation,food supply showed the characteristics of increasing firstly and then decreasing,the difference is that the peaks of the three services appear in different positions,but the water yield shows a trend of decreasing firstly and then increasing.In 1990,with the increasing of human activities,the trade-off between carbon sequestration and soil conservation（regulation Services）increased,and the trade-off between food supply and water yield services（supply services）decreased.The trade-off value between food supply,water yield and regulation services presents the characteristics of double hump type and"V"type;compared with 1990,the trade-off between food supply and regulation services changed from double hump type to single hump type in 2018,and the trade-off between other services was the same as that in 1990 roughly.From 1990 to 2018,the weakening of human activity intensity led to the reduction of food supply and water yield,and the increase of carbon sequestration and soil conservation,and with the increasing intensity of human activity,water yield and soil conservation services were reduced,carbon sequestration and food supply are increased.With the expansion of the value change range of human activity intensity,the value change range of services is also generally expanded.From 1990 to 2018,the increased intensity of human activity led to the trade-off between carbon sequestration,soil conservation and food supply,carbon sequestration and soil conservation generally intensified.The weakening intensity of human activity made the trade-off between carbon sequestration,soil conservation and food supply intensified first and then tended to ease,the change value of trade-off between water yield and other services shows an inverted"U"curve with the expansion of the change range of regional human activity intensity.Therefore,using the characteristics of the ecosystem services and the trade-off between the ecosystem services under the different human activity intensities,as well as the trade-off effects of ecosystem services caused by the change of human activity intensity in time,can help us clarify the regional ecosystem service carrying capacity and formulate ecological restoration tasks in different regions,and provide certain ecological security indicators for those areas where the intensity of human activity will change due to the needs of the social development,so as to protect and improve the regional ecological environment better.