| Understanding the spatiotemporal distribution of multiple ecosystem services and their ecological risk in the context of underlying socio-environmental conditions and climate change is essential for ecological management.The natural ecosystem and the social-economic system are both suffering ecological risk impact to varying degrees.Ecological risk assessment has increasingly become one of the highlights of ecology and environmental sciences which useful to regional ecological decision-making and sustainable development.Ziwuling Area(ZWL)is located in the hinterland of the Loess Plateau.With the vegetation coverage of more than 70% in the core forest area,the natural condition is relatively good.But the topography and landforms are more complex.With a typical continental climate characteristics,the temperature and precipitation vary greatly in time and space.With the increase of population and social economy,the area of urban,industry,mine and transportation expanded continuously.The threat factors to the ecological environment have emerged gradually.Ecosystems have been disturbed and destroyed to varying degrees and facing some degradation risks.Based on the assessment of the four typical ecosystem services of soil conservation,habitat quality,water yield,and food production,this paper aimed to build an ecological risk assessment model based on ecosystem services,to reveal the spatiotemporal changes of ecological risks in ZWL,and to show the potential ecological risk under different scenarios(2 climates and 3 land-use scenarios)in 2050 and 2100.Finally,some management and control recommendations were proposed to avoid ecological risk and aversion and promote regional sustainable development in ZWL.The main conclusions are as follows:(1)Ecosystem services varied greatly in spatial distribution and temporal variation.From 1990 to 2017,the water yield decreased,while soil conservation,habitat quality,and food production increased to varying degrees in ZWL.The area of the high value of habitat quality,soil conservation,and water yield area were mainly distributed in the central and southern part of ZWL.With high vegetation coverage in the core forest,these areas provide a good environmental foundation for ecosystem services.The high food production area was mainly distributed in the central and southern parts of the study area,including Ningxian,Zhengning,Xunyi,Huangling,Yijun,and other counties.(2)There are differences in spatiotemporal variation and structural characteristics of ecological risks.From 1990 to 2017,the ecological risks based on ecosystem services in ZWL changed over time.The soil conservation risk initially increased and then decreased,with the moderate and second-low risks dominated in the ZWL.The water yield risk first increased and then decreased continually,with the high risk being the dominant.The habitat risk first increased and then decreased and then increased,with the second-low and second-high risks dominated in the ZWL.The food production risk first increased,then decreased and then increased,with the high risk dominated in the ZWL.The high-risk area of soil conservation mainly located in the southeast of ZWL and the high-risk areas of water yield was widely distributed in the area north of Ningxian-Huangling.The high-risk area of habitat quality was semi-circularly distributed in the periphery of the core forest area,especially in the southern area of ZWL.The high-risk areas of food production were concentrated in the core forest areas,and the low-risk areas of food production were distributed in the southern outer edge of the core forest areas.The comprehensive ecological risks first increase and then continue to decrease,with medium and low risks as the main ones,with a spatial pattern of high in the north and low in the south.(3)The ecological risk and grade structure in different counties were changed from 1990 to 2017.The soil conservation of all the counties in ZWL was dominated by the moderate risk,and the proportion of the low-risk increased gradually,so the soil conservation risk decreased finally.The structure of water yield risk in each county is relatively stable,the counties in the northern counties were dominated by high and second-high risk,while the counties in the southern ZWL were dominated by the low and second-low risk,such as Xunyi,Yaozhou,Yintai,and Yijun.The habitat quality was dominated by the second-high and second-low risk areas.The structure of food production risk in each county is polarized,the counties in the southern ZWL were dominated by low risk,while the core forest area and the counties in northern ZWL were dominated by the high risk.The comprehensive ecological risks of counties were dominated by medium and second-low risks.During the study period,the ecological risks of northern counties such as Wuqi and Baota were significantly reduced,while the southern Yaozhou and Yintai significantly increased.(4)There are some certain regularities of ecosystem services and ecological risks under different scenarios.Soil conservation services were optimal under SP585 scenarios.Water yield attends highest under ED126 scenarios.Habitat quality is the best under ecological protection scenarios.Under natural development scenarios,food production reaches the highest.Compared with 2050,soil conservation capacity will enhance,water yield will decrease,habitat quality will degrade slightly,and food production will increase in 2100.In 2050,soil conservation will be dominated by low and second-low risk,and soil conservation risk is relatively lower under SSP5-8.5climate scenario.Water yield will be dominated by high risks,and under SSP5-8.5climate scenario the risk is higher.The habitat quality remains relatively stable,dominated by second-low and second-high risks.The food production will be dominated by high risk.In 2100,the high-risk areas for soil conservation will decrease,under the SSP5-8.5 climate scenario will be lower.The risk of water yield will further increase,and the proportion of high-risk under SSP5-8.5 climate scenario will be the largest.The habitat quality will stay stable and the change regularity keeps the same,that is,the risk of habitat quality can be listed as ecological protection scenario <nature protection scenario <economic construction scenario.The risk of food production will increase and dominated by the high risk.(5)The spatial distribution of ecological risks and the clustering characteristics of cold and hot spots in 2050 and 2100.The high ecological risk areas are mainly distributed in the southwest and southeast of ZWL,including Zhengning,Xunyi,Yaozhou,Wangyi,and Yintai.The northern area of Huachi-Ganquan is dominated by the moderate risk.The low-risk areas were mainly distributed in the central areas where Huangling,Xunyi,Yaozhou,Yintai,and Yijun meet.The ecological high-risk area under SSP5-8.5 climate scenario is larger than that of SSP1-2.6 climate scenario,and the area of ecological high-risk in 2100 is larger than that of 2050 under different scenarios.The spatial aggregation of cold and hot spots of ecological risks under different scenarios are almost the same.The hot-spots of the ecological risk are mainly distributed in Ningxian,Zhengning,and Xunyi in the southwest,and Yaozhou and Wang Yi in the southeast of the ZWl,also there is a large cluster located in Baota and Wuqi.The cold-spots of the ecological risk mainly concentrated in the core forest area.Compared with 2050,there will be more high-hot spots and fewer high-cold spots in 2100.The agglomeration of the cold-spots under the ecological protection scenario is the most,and the agglomeration of the hot-spots under the economic construction is the most.(6)Some management measures and suggestions were put forward to reduce the ecological risk in ZWL.Based on the analysis of the spatial distribution,hierarchical structure,cold and hot spots spatial clustering of soil conservation,water yield,habitat quality,food production risks,as well as the comprehensive ecological risk in ZWL from 1990 to 2017 and in the future,some relevant management strategies for ecological risk are proposed.First of all,for the high-risk areas,returning farmland to forest and grass,and prohibiting grazing,water-saving,readjusting the structure of agriculture,intensive land use should be applied strictly.For the moderate and low-risk areas,the existing achievements in ecological construction should be maintained and consolidated to improve the environmental protection consciousness of local residents constantly.Finally,the results can be used for ecological management and risk control to improve human well-being in ZWL and even the entire loess plateau,as well as the sustainable development of social economy. |
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