Impact of urban expansion on the temporal adaptation and spatial connectivity of ecological security patterns: insights from a rapidly urbanizing metropolitan area

Rapid urbanization has further expanded the scale of construction land in urban agglomerations. The encroachment of urban land on ecological land has led to severe ecological problems and threatened the stability of ecological security in urban agglomerations. Analyzing the characteristics of future urban multi-scenario expansion and its impacts on ecological security patterns (ESP) can provide guidance for formulating ecologically sustainable management and control Policies. Our study focuses on Changsha-Zhuzhou-Xiangtan (CZX) urban agglomeration as the study area and establishes an ESP. Additionally, a cellular automata (CA) was used to simulate future urban expansion patterns under three scenarios (i.e., natural development scenario, urban development scenario, and ecological conservation scenario). The subsequent analysis evaluates their impact on the ESP. The simulation results indicate that from 2020 to 2030, the CZX urban agglomeration will undergo rapid urban expansion under the natural development scenario and urban development scenario, characterized by outward growth surrounding the existing construction land. In the natural development scenario, urban expansion is primarily concentrated in the northwest and south directions of construction land, the proportion of construction land increased by 2.78%; in the urban development scenario, it is concentrated in the southeast direction of construction land, the proportion of construction land increased by 3.24%. Ecological conflicts in the aforementioned development scenarios primarily arise in the southwestern region of Changsha County, as well as the southern areas of Kaifu District and Furong District. Conversely, under the ecological conservation scenario, the rate of urban expansion has significantly decreased, environmental preservation is upheld at its highest level, and the proportion of construction land only increased by 0.04%. Based on the simulation results, we present targeted recommendations for urban land planning and growth management, as well as the protection, restoration, monitoring, and development of ecological land. These suggestions provide effective guidance for improving the stability of ESP in urban agglomerations and promoting high-quality development in Chinese urban agglomerations.

The urban agglomerations' rapid expansion and population growth have led to the fragmentation of landscape patterns and the degradation of ecosystems, seriously threatening regional ecological security. Ecological security pattern (ESP) is a spatial planning approach to effectively balance the development of urbanization and ecological protection. However, previous studies have ignored the difference in the importance of ecosystem services and the spatial compactness of ecological sources. The quantitative management objectives for maintaining the resilience of ESP are also rarely discussed. In this study, taking the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) as an example, ecological sources were identified by simulating multiple ES weight assignment scenarios through GeoSOS area optimization. Ecological corridors and strategic points were extracted by Linkage Mapper. The robustness analysis based on complex network theory was performed to quantify the management objectives of ESPs. The results showed that ESPs include 26,130.61 km2 ecological sources (accounting for 46.6% of the area of GBA), 557 ecological corridors, and 112 ecological strategic points. In more detail, ecological sources are mainly distributed in the western and eastern mountainous areas, and ecological corridors primarily link peripheral edge areas of GBA in a circular radial shape. Compared with the current nature reserves, the identified ecological sources are more compact in landscape pattern. According to the robustness analysis, at least 23% of the important ecological sources should be strictly restricted from development activities to maintain the ESP's ability to resist ecological risks. This study also proposed corresponding differentiated ESPs management strategies. By optimizing the existing ESPs construction method and clarifying the ESPs management strategies, this study provides a completely scientific framework for the construction and management of ESPs in urban agglomerations.

Prediction of ecological security patterns based on urban expansion: A case study of Chengdu

Integrating the ordered weighted averaging method to establish an ecological security pattern for the Jianghuai ecological economic zone in China: Synergistic intraregional development

The conversion of Earth's land surface to urban uses is one of the most irreversible human impacts on the global biosphere. It drives the loss of farmland, affects local climate, fragments habitats, and threatens biodiversity. Here we present a meta-analysis of 326 studies that have used remotely sensed images to map urban land conversion. We report a worldwide observed increase in urban land area of 58,000 km2 from 1970 to 2000. India, China, and Africa have experienced the highest rates of urban land expansion, and the largest change in total urban extent has occurred in North America. Across all regions and for all three decades, urban land expansion rates are higher than or equal to urban population growth rates, suggesting that urban growth is becoming more expansive than compact. Annual growth in GDP per capita drives approximately half of the observed urban land expansion in China but only moderately affects urban expansion in India and Africa, where urban land expansion is driven more by urban population growth. In high income countries, rates of urban land expansion are slower and increasingly related to GDP growth. However, in North America, population growth contributes more to urban expansion than it does in Europe. Much of the observed variation in urban expansion was not captured by either population, GDP, or other variables in the model. This suggests that contemporary urban expansion is related to a variety of factors difficult to observe comprehensively at the global level, including international capital flows, the informal economy, land use policy, and generalized transport costs. Using the results from the global model, we develop forecasts for new urban land cover using SRES Scenarios. Our results show that by 2030, global urban land cover will increase between 430,000 km2 and 12,568,000 km2, with an estimate of 1,527,000 km2 more likely.

成渝地区双城经济圈生态安全格局识别及改善对策

The three mega urban agglomerations of Beijing-Tianjin-Hebei (BTH), the Yangtze River Delta (YRD), and the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) in eastern China serve as core economic hubs and focal areas for ecological challenges. Establishing an ecological security pattern (ESP) is crucial for balancing economic growth with ecological sustainability. However, previous studies have often overlooked the resilience of ecosystems in recovering to a stable state, which undermines the robustness of ESPs in addressing future risks. Additionally, limited research has focused on enhancing the spatial connectivity of ESPs by incorporating the intrinsic characteristics and spatial configurations of ecological sources (ESs) and ecological corridors (ECs), hindering the development of functionally robust and structurally integrated ESPs. This study assessed ecological resilience using 2020 land use data. Following the framework of "ecological source identification-ecological resistance surface setting-ecological corridor extraction, " areas with high ecological resilience were identified as ESs, and the minimum cumulative resistance (MCR) model was applied to extract ECs that connect these ESs. A multi-indicator system was then developed to evaluate the ESPs. By determining critical thresholds for downgrading ESs and ECs and analyzing the spatial configuration of the ESPs within these urban agglomerations, optimized strategies were proposed. The results showed that: ① The mega urban agglomerations exhibited moderate ecological resilience, with GBA leading at 0.59, followed by YRD at 0.51, and BTH at 0.50. Urban areas generally demonstrated low resilience, while forests, grasslands, and water bodies were characterized by higher resilience. ② ESs were identified within the three mega urban agglomerations, covering 14.7%, 13.9%, and 24.7% of their respective areas. A total of 112, 145, and 57 ECs were extracted. Each urban agglomeration contained several small, low-grade ESs (numbering 11, 9, and 2) and longer low-grade ECs (numbering 10, 8, and 5). ③ To enhance indicators such as the resilience and permeability of low-grade ESs and ECs, it is recommended that BTH and GBA prioritize reinforcing high-quality ECs to leverage the "strong supporting weak" effect between high- and low-grade ESs. BTH and YRD should focus on land use planning and water resource management. All three urban agglomerations should establish ecological buffer zones and "stepping stones." Additionally, new ESs should be added in the ESP gap areas of BTH and GBA to improve overall coverage, uniformity, and spatial connectivity. Optimized ESP strategies integrating enhanced ecological resilience with improved spatial connectivity include: "three horizontal, two vertical, one belt" for BTH; "three sides, multiple cores, multiple corridors" for YRD; and "two horizontal, two vertical, three areas" for GBA. These findings provide valuable insights for the strategic management of ecosystems within urban agglomerations.

Integrating “quality-risk-demand” framework and circuit theory to identify spatial range and priority area of ecological security pattern in a rapidly urbanizing landscape

Rapid urbanization has affected ecosystem stability, and the construction of ecological security patterns (ESPs) can rationally allocate resources and achieve ecological protection. Priority evaluation of critical areas can maximize the benefits of ecological protection, which is crucial for sustainable urban development. However, most prior studies have focused on assessing individual elements of the ESP, rarely considering both the protection priority of ecological sources and corridors. We constructed ESPs for the Wuhan Metropolitan Area (WMA) from 2000 to 2020 and evaluated the priority of ecological sources and corridors for protection. The findings indicated that high-level ecological sources exhibited higher overall landscape connectivity and ecosystem service values with lower patch fragmentation. The average area proportions of primary, secondary, and tertiary ecological sources in 2000, 2010, and 2020 were 41.11%, 23.03%, and 29.86%, respectively. High-level ecological corridors had shorter lengths and offered higher comprehensive ecosystem service values. The total length of secondary corridors exceeded that of primary corridors by 1951.19 km, 650.39 km, and 2238.18 km in 2000, 2010, and 2020, respectively. Primary corridors, which connected fragmented and isolated sources, should have their ecological land percentage increased to enhance connectivity. Secondary corridors connected two independent and distant sources, providing the basis for ecological protection in the intervening area, whose surrounding habitats should be protected. This study identifies the ecological protection priority and offers a theoretical basis and practical reference for balancing urban development with ecological protection.

Integrating ecosystem service trade-offs and rocky desertification into ecological security pattern construction in the Daning river basin of southwest China

The main goal of constructing ecological security patterns (ESPs) is to identify ecological sources, corridors and nodes that play significant roles in sustainable development on a regional scale. Although there are many studies on the construction of ESPs, there is no consensus in terms of research methodology and systematic frameworks for integrated landscape management. Based on land use data from 2000, 2010, and 2020 of Chongqing Municipality in southwest China, we evaluated the spatial-temporal variation of ESPs by integrating InVEST and Circuit Theory. Results showed that: (a) Habitat quality varied through space, with habitat quality being lower in the western and central regions and higher in the southeastern and northeastern regions. (b) The area of lower quality habitat across different time periods was more than 46%, and habitat quality over the last two decades has generally been low with no significant improvement. (c) From 2000 to 2020, ecological sources were primarily distributed in the mountainous areas with high habitat quality and fractional vegetation coverage in the northeast and southeast. The regions identified ecological sources in 2000, 2010, and 2020 accounted for 31.37, 33.53, and 32.7% of Chongqing Municipality, respectively. (d) The ESPs were composed of ecological sources dominated by forests, connected by continuous ecological corridors. The current ESPs of Chongqing Municipality included 20 ecological nodes, 17 continuous ecological corridors and 23 ecological sources. We strongly suggest the local governments strengthen the protection of the identified ecological nodes, ecological corridors, ecological sources, and protection gaps, and focus on strengthening the construction and management of the ecological corridor network system to promote species diffusion and gene exchange. Our findings are helpful for policy makers to introduce appropriate measures to objectively guide urban expansion via rational and sustainable development of land resources and improve the level of ecological security for Chongqing Municipality.

Trade-off between comprehensive and specific ecosystem characteristics conservation in ecological security pattern construction

The establishment of ecological security patterns (ESPs) represents a significant paradigm shift in the approach to sustainable development. ESPs aim to reconcile the typically conflicting interests of ecological conservation and economic growth by guaranteeing the sustainability of critical ecosystem services and preserving the ecological integrity of the region while promoting socio-economic development. The primary objective of ESPs is to achieve a balanced and harmonious relationship between human society and the natural environment. The Qiandongnan Ecotourism Area (QEA) located in Southwest China is renowned for its high biodiversity; however, the ecological environment in the region is highly fragile. In light of this, there is an urgent need to establish ESPs for QEA that can promote ecological protection and sustainable economic development. In this study, we used land-use and land-cover change data and human disturbance factors to identify the ESPs of the Qiandongnan Ecotourism Area (QEA), employing the InVEST model and Circuit Theory. Our results revealed that (1) the ecological quality of the study area is relatively high, with high-quality habitat areas covering 19,554.76 km2, which account for approximately 64.57% of the study area and the overall ecological environment is in a healthy condition; (2) the total area of ecological sources covers approximately 17,616.27 km2, accounting for approximately 58.17% of the study area, primarily distributed in Liping, Rongjiang, and Congjiang, which respectively account for 16.28%, 12.44%, and 11.86% of the total ecological source area; (3) the ESPs are composed of 13 key ecological nodes, 17 ecological corridors (with a length of approximately 1474.47 km), and 21 ecological source clusters. The ecological corridors are distributed in a ring shape, connecting various ecological nodes and sources along mountains, forests, rivers, and valleys. These findings provide a theoretical foundation for the protection of the ecological system’s integrity and the development of social and economic activities in the QEA.

基于生态系统服务价值重构的干旱内陆河流域生态安全格局优化——以张掖市甘州区为例

Impacts of multi-scenario land use change on ecosystem services and ecological security pattern: A case study of the Yellow River Delta