GIS-based Ecological Effect Assessment Of The Southern End Of The Hu Huanyong Line

Yunnan Province and Sichuan Province,located at the southern end of Hu Huanyong Line,is the first and second terrain transition zone of China.The southern intersection zone of Hu Huanyong Line,an ecologically fragile area,is a hot spot for the development of population and economy,which fully reflects the complex process of coupling nature and humanity and the mutual feedback relationship.At present,the assessment for ecological effects of single factor or scale can not meet the needs of coordinated development of regional economy and environment and optimization of land spatial pattern,and the most suitable degree of coordinated economic development is difficult to measure.In this paper,the regional ecological effects of long time series were evaluated comprehensively by using GIS techno logy.The ecosystem health of the study area(Sichuan and Yunnan Province)in the past 20 years was evaluated at the city level,and the spatial evolution characteristics were analyzed in depth.Through the downscaling model,the county-level evaluation index data were obtained,and the county-level evaluation of ecosystem health was completed.Meanwhile,the evaluation framework of ecological carrying capacity was constructed,and the changes of ecological carrying capacity at provincial level in recent 20 years were conpared with it to verify the accuracy of the assessment.To achieve a more comprehensive assessment of ecological effects,on the basis of carrying capacity evaluation,the improved three-dimensional trade-off model is used to explore the appropriate development speed of each factor and solve the contradictions in development.Finally,the ecological effect evaluation of the regional natural and human complex system has been conpleted.The findings from this study could contribute to formulate a reasonable ecological and environmental protection policy and development direction,guaranteeing ecosystem services in the long run.This paper analyzed the spatial and temporal pattern of the basic ecological elements in the study area.The results show that climate change in the east area of Hu Huanyong Line is more sensitive than that in the west.The degradation trend of vegetation in the east area is more obvious than that in the west.Under the protection of ecological engineering,the restoration effect of vegetation is significant,but the soil condition and nutrient recovery are poor.This paper assessed the ecosystem health condition by using the pressure-state-response model.We analyzed thoroughly the spatial-temporal pattern in regional ecosystem health condition during recent two decade(2000-2016)from overall characteristics and local characteristics.Ecosystem health of more than 70%of the area has improved over time(Y=0.004X-7.218,RZ=0.96,P<0.001).Primacy ratio and variation coefficient analysis confirms that the gap among regions is gradually expanding.Overall,the regional ecosystem on the right side of the Hu line was slightly healthier than that on the left.The pressure and state scores of ecosystem are largely determined by physical geography condition,and response scores by policy orientation.The results of ecosystem health assessment at county level are basically consistent with those at city level,and the differences on both sides of Hu Huanyong Line are basically the same.Based on an evaluation of ecological carrying capacity(ECC),we have constructed a three-dimensional trade-off model for socially harmonious development for the Sichuan and Yunnan regions in south-west China.The results demonstrate that there is a continuous increase in socio-economic coordination(SEC)(slope>0.23,R2>0.94,p<0.0001).Significant government aid during the post-disaster reconstruction and more attention being paid to the environment in policy resulted in a faster increase in ECC(slope>0.38,R2>0.93,p<0.001)from 2008 to 2016.Two regions with backward economy(SEC trade-off valve<0)and abundant resources(REC trade-off valve>0)in the early 21st century had an overheated economy(SEC trade-off valve>0)driven by governmental policies after 2006.More considerable coordinated development occurred in Yunnan since 2006,and it(trade off value<0.1)have exceeded Sichuan(trade-off value>0.2)gradually.The trade-off model shows that the period around 2005 or 2016 is the best period for the coordinated development of economy and society in Yunnan.