The Construction of a Regional Ecological Security Pattern Based on Circuit Theory

Integrated assessment and prediction of ecological security in typical ecologically fragile areas

In order to safeguard and restore ecological security in ecologically fragile regions, a regionally appropriate land use structure and ecological security pattern should be constructed. Previous ecological security research models for ecologically fragile areas are relatively homogenous, and it is necessary to establish a multi-modeling framework to consider integrated ecological issues. This study proposes a coupled "PLUS-ESI-Circuit Theory" framework for multi-scenario ecological security assessment of the Ningxia Hui Autonomous Region (NHAR). Firstly, the PLUS model was used to complete the simulation of four future development scenarios. Secondly, a new ecological security index (ESI) is constructed by synthesizing ecological service function, ecological health, and ecological risk. Finally, the Circuit Theory is applied to construct the ecological security pattern under multiple scenarios, and the optimization strategy of ecological security zoning is proposed. The results show that (1) from 2000 to 2030, the NHAR has about 80% of grassland and farmland. The built-up area is consistently growing. (2) Between 2000 and 2030, high ecological security areas are primarily located in Helan Mountain, Liupan Mountain, and the central part of NHAR, while the low ecological security areas are dominated by Shapotou District and Yinchuan City. (3) After 2010, the aggregation of high-security areas decreases, and the fragmentation of patches is obvious. Landscape fragmentation would increase under the economic development (ED) scenario and would be somewhat ameliorated by the ecological protection (EP) and balanced development (BD) scenarios. (4) The number of sources increases but the area decreases from 2000 to 2020. The quantity of ecological elements is on the rise. Ecological restoration and protection of this part of the country will improve its ecological security.

Construction of Ecological Security Pattern and Identification of Ecological Restoration Zones in the City of Changchun, China

Identification of crucial regions in need of ecological conservation and restoration based on ecological security patterns is of utmost importance for ecological restoration across national land space with regard to China's promotion of ecological civilization. Using Changchun, the capital of northeast China, as an illustration, the study chooses ecological sources based on the importance of ecosystem services, builds an ecological security pattern using circuit theory, and organizes critical regions for ecological conservation and restoration. The findings reveal that the 20 ecological sources chosen based on ecosystem services are more concentrated on the eastern side of the city, whereas the western side of the city has a smaller overall area; 41 ecological corridors show a network distribution, among which the southeast is relatively densely distributed; 31 ecological pinch points and 15 ecological barrier points are also identified. Prioritized restoration zones, prioritized protection zones, key conservation zones, and general conservation zones were the four different types of ecological restoration regions identified by the study. Each district's prioritized restoration zones in the main metropolitan area are larger than the others; Gongzhuling's priority protection zones are the largest, and Yushu's natural substrate is the best. According to the grading, targeted solutions are suggested, offering helpful advice for the improvement of ecological patterns and ecological restoration of the aforementioned national areas.

Integrating CVOR-GWLR-Circuit model into construction of ecological security pattern in Yunnan Province, China

In the traditional construction of ecological security pattern, the minimum cost path is extracted as the ecological corridor based on the minimum cumulative resistance model, and the ecological nodes are identified manually. This method lacks the consideration of the exchange process of energy flow and information flow in the ecological process, resulting in a certain lack of ecological security pattern in structure and function. Therefore, an ecological security pattern construction method integrating CVOR-GWLR-Circuit model is proposed to solve the above problems by transforming natural background data into localized correction variables and adding them to the ecological security pattern evaluation model. Taking Yunnan Province as an example, firstly, the ecological security evaluation system of "Contribution, Vigor, Organization, Resilience" (CVOR) is constructed based on the importance of ecosystem services and ecosystem health, and the ecological security of Yunnan Province in 2020 is evaluated, and the ecological source areas are identified combined with nature reserves. Then, the ecological resistance surface was constructed by considering land use data and topographic factors, and the landslide sensitivity evaluation model was constructed based on geographically weighted logistic regression model (GWLR) to correct the basic resistance surface. Finally, the circuit theory model is used to extract the ecological corridor and construct the ecological security pattern in Yunnan Province. The ecological pinch points and barriers in the ecological corridor are diagnosed by the current density, so as to identify the width of the ecological corridor and identify the key areas of ecological protection and restoration. The results showed that the ecological sources area of Yunnan Province was about 69,417.78 km2, accounting for 17.6% of the total area of the study area, mainly distributed in Dehong Prefecture, southwest Yunnan, Diqing Prefecture and Nujiang Prefecture in northwest Yunnan. A total of 780 ecological corridors were generated between the ecological sources, with a total length of about 197,598.2 km, an average length of 253.3 km, and the longest path length of 932.1 km. The ecological corridors are "spider web", linking southwest, northwest, northeast, central and southeast Yunnan Province. 36 ecological pinch points and 42 ecological barriers were identified. The research results verify that the ecological security pattern constructed by integrated CVOR-GWLR-Circuit model is more reasonable, which can provide scientific basis for regional ecological protection planning and ecological corridors design.

Green Infrastructure Network Identification at a Regional Scale: The Case of Nanjing Metropolitan Area, China

Clustered urban development has caused increasing fragmentation and islanding of regional ecological spaces. Creating a green infrastructure network (GIN) is a practical method of ensuring regional ecological security. This study proposed a method of GIN identification at the regional scale based on the Nanjing Metropolitan Area as an example. In this method, green hubs were identified using morphological spatial pattern analysis and connectivity indexes, green corridors were simulated based on the least-cost path model, and key optimization nodes were identified using circuit theory. The results indicated that green hubs covered an area of 5042.07 km2, of which, 15.40% were cross-border, and the potential corridors were distributed in a network, with the key ecological nodes primarily narrowly situated. By comparing the hubs with the statutory green space protection area and the urban ecological control line, the identification results were more than 70% accurate, showing that the results were valid and reliable. This method not only made the identification of regional GIN more practical and replicable but also further identified key areas that need priority protection. This study provides a method for constructing regional GIN and serves as a strong guide for ecological and development planning of other urban clustered areas.

Construction of Ecological Security Pattern Based on the Importance of Ecological Protection—A Case Study of Guangxi, a Karst Region in China

The ecological security pattern is an important way to coordinate the contradiction between regional economic development and ecological protection and is conducive to promoting regional sustainable development. This study examines Guangxi, a karst region in China. The ecosystem service function and ecological environment sensitivity were both selected to evaluate the ecological conservation importance, and based on the results of the ecological conservation importance evaluation, suitable patches were selected as ecological sources. Meanwhile, resistance factors were selected from both natural factors and human activities to construct a comprehensive resistance surface, circuit theory was used to identify ecological corridors, ecological pinch points, and ecological barrier points, and ecological protection suggestions were then proposed. The results show that there are 50 patches of ecological sources in Guangxi, with a total area of 60,556.99 km2; 115 ecological corridors, with the longest corridor reaching 194.97 km; 301 ecological pinch points, whose spatial distribution is fragmented; and 286 ecological barrier points, most of which are concentrated in the central part of Guangxi. The results of this study provide a reference for the construction of ecological security patterns and ecological conservation in developing countries and karst areas.

Construction of Regional Ecological Security Patterns Based on Multi-Criteria Decision Making and Circuit Theory

The scientific identification of key areas for regional ecological protection represents an important basis for maintaining regional ecological stability and enhancing regional development. It is also a developing methodology of landscape ecology (LE) research. The strategic ecological protection and integrated development of the Yangtze River Delta region is of critical significance for promoting the construction of ecological civilization in the watershed and improving societal health. Here, we analyze Anhui Province and select important ecosystem service functions (biodiversity, carbon fixation, soil conservation function, and water retention) in the study area. We construct a spatial pattern of ecosystem services for multiple scenarios based on the multi-criteria decision-making method ordered weighted averaging (OWA), calculate the trade-off degree and conservation efficiency of each scenario, identify ecological priority conservation areas, use circuit theory to explore ecological corridors and key areas and to construct regional ecological corridors, and identify regional pinch points and barrier points which may impede the construction of regional ecological security patterns. The study area is divided into an ecological protection zone, ecological buffer zone, ecological transition zone, ecological optimization zone, and ecological governance zone. Our results show that: (1) the four types of ecosystems in the study area have similar spatial distribution patterns, with an overall spatial characteristic of “high in the southwest and low in the northeast”; (2) the four types of ecosystem services in the study area show synergistic relationships at the provincial scale, but in areas with different natural and geographical characteristics, there are both synergistic and trade-off relationships between different ecosystem services; (3) a total of 121 ecological source sites were identified in the study area based on multi-criteria decision making which cover an area of 43,222.26 km2, accounting for 30.87% of the total area of the study area; and (4) a total of 250 ecological corridors, 54 pinch points, and 24 barrier points were identified in the study area based on circuit theory. Our results may provide decision support for ecological restoration and land use structure optimization in Anhui Province and other regions.

Linking Morphological Spatial Pattern Analysis and Circuit Theory to Identify Ecological Security Pattern in the Loess Plateau: Taking Shuozhou City as an Example

Located in an ecologically fragile area in China’s eastern part of the Loess Plateau, Shuozhou City has faced environmental challenges imposed by frequent urban expansion and mining activities in recent years. As ecological security patterns (ESP) identification and optimization are significant to regional biodiversity and ecosystem services, this study combined morphological spatial pattern analysis (MSPA) and circuit theory to construct and optimize regional ESP. Results show the number and area of ecological sources in the study area decreased from 21 to 20 between 2010 and 2017. The total area of ecological sources fell from 1923.35 km2 to 1869.37 km2, with their proportion in the study area dropped from 18.14% to 17.64%. From 2010 to 2017, the number of obstacles increases from 63 to 80, mainly consisting of farmland, unused land, transportation land, and construction land. The area of obstacles reached 10.17 km2 in 2017. A framework of “one protection area, two regulation areas, and three restoration areas” is proposed to optimize the ESP of the study zone. This study explored a combination of ESP analysis tools and focused on improving regional ecosystem service and biodiversity. It will support local urban planning and provide a reference for similar studies in resource-based cities.

Construction of Ecological Network Based on Multi-Scale Conversion and Nesting

Ecological protection and the restoration of full-array ecosystems is an important part of ecological civilization construction, which is a powerful measure to implement the concept of green development and help bridge the gap between the respective inevitable requirements of the current ecological environment and economic development. To solve this problem, a multi-scale index system was constructed to identify ecological sources comprehensively. The minimum-cost path method, the circuit theory, and the cyclic window search method were adopted to quantitatively identify the important ecological sources and corridors in scale nesting and pinch points and barrier points that affect multi-level connectivity. Furthermore, the specific optimization layout strategy of the ecological network structure of the Hefei metropolitan area was proposed. According to the results, if ecological sources and corridors at two scales are overlaid, the coincident area of ecological sources at two scales is 1719.95 km2. As important ecological sources, Chaohu Lake Basin, Niuwangzhai, and Wuding Mountain, which are important areas to maintain the ecological network, need to be protected. Ten overlapping ecological corridors, which are mainly distributed in Changfeng County, are easily damaged long term. As a result, ecological nodes should be set up as temporary habitats for species transfer. In addition, based on the circuit theory and the cyclic window search method, calculating areas of pinch points at two scales yields 1637.75 km2 and 434.22 km2, respectively, and for areas of barrier points yields 2182.75 km2 and 126.97 km2, respectively. The ecological pinch points at two overlapping scales among them are important areas for future protection. Due to the small and fragmented spatial distribution in the urban area, pinch points with an average size of 0.58 km2 are easy to be restored and will greatly improve the connectivity of the ecological network after restoration. Furthermore, through the quantitative identification of ecological network elements of two scales, the paper puts forward an optimization strategy for an ecological network in the Hefei metropolitan area from three aspects of “point-line-polygon.” The research results can reference decision-making concerning the delineation of urban growth boundary, regional ecological security pattern, land space renovation, and ecosystem restoration.

Integrating the MCR and DOI models to construct an ecological security network for the urban agglomeration around Poyang Lake, China

The development of urban agglomeration in aquatic areas is premised on ecological security. The construction of ecological security network is an effective measure to reduce ecological resistance and guarantee economic development. In this study, a comprehensive ecological security network (ESN) evaluation approach is developed by integrating the Minimum Cumulative Resistance (MCR) model and Duranton and Overman Index (DOI). Taking the urban agglomeration around Poyang Lake in 2015 as a case, the MCR model showed the ecological landscape pattern of discrete connection and large overall ecological resistance. The DOI model indicated that the industries of moderately polluted were global localization, while heavily polluted were small-scale localization and large-scale dispersion. Accordingly, the ESN consisting of 35 ecological sources, 34 ecological corridors, 57 artificial corridors, and 39 eco-economic strategic nodes can avoid the threat of industrial layout to the ecological landscape. The results of this study complemented the guidance of industrial agglomeration theory on the basis of "source-sink" theory. The dual evaluation approach of landscape ecology and economic agglomeration proposed in this study explores interdisciplinary data fusion of different scales, and also provides a reference for inter-municipal coordinated ecological management and restraining urban excessive expansion.

Regional Land Eco-Security Evaluation for the Mining City of Daye in China Using the GIS-Based Grey TOPSIS Method

Regional ecological security assessment is a significant methodology for environmental protection, land utilisation, and human development. This study aims to reveal the regional constraints of ecological resources to overcome the difficulties and complexities in quantification of current models used in land ecosystems. For this purpose, the technique for order preference by similarity to an ideal solution (TOPSIS) was linked to a grey relational analysis and integrated with a geographic information system. The obtained method was used to construct a land eco-security evaluation on a regional scale for application in a traditional mining city, Daye, in central China. Parameter analysis was introduced to the method to produce a more realistic spatial distribution of eco-security. Subsequently, based on the pressure–state–response framework, the eco-security index was calculated, and the carrying capacity of land resources and population for each sub-region were analysed. The results showed that: (i) very insecure and insecure classes comprised 5.65% and 18.2% of the total area, respectively, highlighting the vulnerable eco-environmental situation; (ii) moderate secure classes areas comprised a large amount of arable land, spanning an area of 494.5 km2; (iii) secure areas were distributed in the northwest, containing mostly water and wetland areas and accounting for 426.3 km2; and (iv) very secure areas were located on the southeastern region, involving traditional woodland with a better vegetation cover and an overall higher eco-environmental quality. In addition, for each sub-region, the extremely low and low ecological security areas were mainly arable and urban lands, which amounted to 305 and 190 km2, respectively. Under the current ecological constraints, sub-region 1 cannot continue supporting the population size in Daye City. The present results demonstrate the accuracy of our methodology, and our method may be used by local managers to make effective decisions for regional environment protection and sustainable use of land resources.

Simulating Urban Growth Scenarios Based on Ecological Security Pattern: A Case Study in Quanzhou, China

In recent decades, the ecological security pattern (ESP) has drawn increasing scientific attention against the backdrop of rapid urbanization and worsening ecological environment. Despite numerous achievements in identifying and constructing the ecological security pattern, limited attention has been paid on applying ESP to predict urban growth. To bridge the research gap, this paper took Quanzhou, China as a study case and incorporated the identified ESP into an urban growth simulation with three distinct scenarios. Following the “ecological source–ecological corridor–ecological security pattern” paradigm, the ESP identification was carried out from four single aspects (i.e., water, geology, biodiversity, and recreation) into three levels (i.e., basic ESP, intermediate ESP, and optimal ESP). Grounded in an equally weighted superposition algorithm, the four single ESPs were combined as an integrated ESP (IESP) with three levels. Taking IESP as an exclusion element, urban growth simulation in 2030 was completed with thee SLEUTH model. Drawing on the three levels of IESP, our urban growth simulation contained three scenarios. In terms of urban sprawl distribution coupled with urban growth rate, an optimal urban growth scenario is recommended in this paper to balance both urban development and eco-environment protection. We argue that our ESP-based urban growth simulation results shed new light on predicting urban sprawl and have the potential to inform planners and policymakers to contribute to more environmentally-friendly urban development.

Establishing Ecological Security Patterns Based on Reconstructed Ecosystem Services Value in Rapidly Urbanizing Areas: A Case Study in Zhuhai City, China

Rapid urbanization has caused a reduction in green lands, negatively affecting the functions of ecosystem services (ESs). The 11th goal and other goals of the United Nations Sustainable Development Goals (SDGs) have highlighted the importance of the balanced development of cities and the environment. ESs are essential for human well-being, so their application in sustainable development study is indispensable. The ecological security pattern (ESP) provides an integrated strategy for maintaining a balance between a sustainable supply of ESs and urbanization. However, establishing an ESP with the goal of satisfying human requirements for ESs in a rapidly urbanizing area has not been well studied. Thus, it is necessary to build an ESP based on ecosystem service value (ESV) reconstruction to manage urban ecosystems sustainably. Based on land use data and field data, this study approached the research gap by related analyses. The first analysis involved dynamic reconstruction of ESVs using the static ESV and importance indices of ESs from 1999–2013. The second analysis involved using hot spot analysis (Getis-Ord Gi * statistics) to distinguish heterogeneous units of the dynamic ESV to identify ecological sources. The third analysis involved establishing the ESP in Zhuhai city, using the minimum cumulative resistance (MCR) model. The results indicated that the ESV of Zhuhai city displayed an upward trend. The functions of water conservation and waste treatment contributed most to the total ESV, while grain production and raw material contributed least in the study area. In the restructuring of ESVs in 2005, 2009, and 2013, the per unit area of the ESV decreased slightly. The areas with high ESVs continued to shrink, while the areas with low ESVs gradually expanded. The ESP of Zhuhai city exhibits great connectivity and strong plasticity, which specifically provides a reliable and visual way to build sustainable cities from a quantitative perspective, generally consistent with the urban ecological planning of Zhuhai city. This study provides an important reference for the application of ESs to achieve SDGs in coastal, rapidly urbanizing regions.