| The rapid advancement of urbanization has exposed a series of development problems.The development path at the expense of ecology has significant drawbacks.Actively promoting the construction of regional ecological civilization and the sustainable development path of coordinated “production-living-ecology” has become the main model of urban expansion.The regional ecological security pattern is an important tool that helps regional coordinate social development and ecological security.It is an important guarantee for maintaining terrestrial ecological security and can promote sustainable social development.At present,a paradigm for constructing the regional ecological security pattern has been formed.But the analysis of the effects of its constituent elements on the overall stability of the pattern is lacking.Based on the current research gap that lack of discussion on the topological structural elements and the overall relationship of the regional ecological security pattern.And the relevant theories and analytical methods of complex networks,we selected the Guizhou Province as research area(typical ecologically fragile area in southwest China).Then using the "load-capacity" cascade failure model to explore the importance of ecological sources to the overall pattern and clarify the structural weaknesses of the regional ecological security pattern.Based on the research paradigm and the social-economic status of Guizhou province in 2015,this paper analyzed the ecological importance from four aspects: habitat quality,water purification function,carbon storage,and soil conservation.Based on the screening basis,280 ecological sources were identified;750 ecological corridors were identified based on the minimum cumulative resistance model;pinch points were identified based on the boundary between the ecological corridors and the main traffic lines.Then the ecological security pattern of Guizhou Province was constructed.This paper used complex network theory to abstract it as an unauthorized and undirected ecological network.Based on that,we used the cascading failure model to analyze he node of the ecological network,and the impact of “grain for green”(in recent)and urban expansion under different development scenarios(in future)on the ESP.The results showed that:(1)The ecological status of Guizhou Province was good.The total area of important ecological areas and core ecological areas accounted for 38.98% of the total area of the whole province.The area of core ecological areas accounted for 11.66% of the whole province.The ecological resources of each administrative area had significant differences.The Miao and Dong Autonomous Prefecture in Southeast Guizhou has the largest number of ecological source areas,and the lowest number of ecological source areas in Liupanshui City.(2)The range of vulnerability of the overall pattern is 0.0251 ～ 0.2151,corresponding to the cascading failure scale of 7 ～ 60 ecological sources.The average level of pattern vulnerability is 0.0719,corresponding to the cascading failure scale of 20 ecological sources.The average level of pattern vulnerability is 0.0719,corresponding to the cascading failure scale of 20 ecological sources.Therefore,the stability of the network is significantly affected by structural weaknesses.And the vulnerable nodes in the network should be focused on.Thees source areas should be at the core of all sources,which are the typical vulnerable points in the overall network.The No.60 source area in Bijie City,No.79 source area number in Qiannan Buyi and Miao Autonomous Prefecture and No.204 source area in Anshun City have the same cascading failure scale.These sources have the lowest cascading failure scale and the lowest importance in the overall ecological security landscape.(3)Different administrative regions showed significant differences in the total scale of cascading failures and the average cost of loss in ecological source areas.The region with the largest total scale of regional cascading failures was Qiandongnan Miao and Dong Autonomous Prefecture,and the smallest was Liupanshui City.The highest average cost of ecological source loss was Guiyang City,and the lowest was Liupanshui City.When a large-scale ecological crisis occurs(such as mountain fires,large-scale flash floods,earthquakes,etc.),the Miao and Dong Autonomous Prefecture in Southeast Guizhou should be protected first.Liupanshui City may be at the end of the protection sequence.The daily ecological construction,restoration and other processes should give priority to the protection of the ecological source in Guiyang City,and Liupanshui City can be located at the rear of the protection sequence.(4)The recent measures of “grain for green” will not have a significant impact on ecological sources,but will change the number and spatial location of ecological corridors.After it,the cascading failure effect of 75 ecological source areas will be weakened,and the cascading failure effect of 137 ecological source areas will be enhanced.Overall,it had not shown a negative impact on the ecological security pattern.Under the development scenarios of Guizhou Province in 2030,the rigid urban growth boundary and the ecological sources will produce different degrees of overlap.But the rigid urban growth boundaries will not cause a significant impact on the ecological security pattern,nor will it cause a cascading failure effect.Based on these conclusions,this article proposed the following suggestions for ecological safety maintenance in Guizhou Province:(1)Establish a differentiated ecological security construction,maintenance,and restoration system to ensure that limited funds and materials are used in key areas of regional ecological security;(2)Viewing the impacts of measures such as grain for green project and farmland protection on the regional ecological security pattern in many ways.Then coordinating ecological security and food security;(3)Strictly controlling the boundaries of urban growth,exploring smart urban growth paths,increasing the potential of internal digging,and preventing urban growth boundaries from exceeding expectations in the future development process will have significant impacts on regional ecological security patterns. |
