Sustainable Cities and Society，October 2024
Yuan Wang, Han Wang, Fei Yao, Rudi Stouffs, Jiansheng Wu
Abstract: An urban heat island (UHI) refers to a metropolitan area significantly warmer than its rural surroundings. Accurately quantifying UHI intensity (UHII) relies on selecting appropriate rural areas, which lack a universal definition. A crucial aspect in UHII quantification is considering the spatial extent of the UHI effect, known as its footprints (UHIFP). Here, we propose a framework to jointly estimate UHII and UHIFP, integrating the latter into the former. Our approach involves creating 12 equal-area buffer zones around each urban boundary and initially selecting the three farthest zones as rural areas. Using a seamless 1-km daily land surface temperature dataset on Google Earth Engine, we construct exponential decay models to characterize the temperature variations along the urban-area gradient of each city and to extract UHIFP from these models. The results reveal that the average UHIFP during daytime and nighttime are 2.6 and 2.7 times of the urban size, respectively, predominantly located before the three farthest buffer zones, thereby verifying the effectiveness of the selected rural areas for accurate UHII calculations. This framework is critical for evaluating the risks associated with extreme heatwaves and heat stress. It also provides suggestions for UHI mitigation measures from an urban–rural gradient perspective.
Journal of Environmental Management, October 2024
Tian Hu, Jiansheng Wu
Abstract:Global climate change has necessitated the implementation of green infrastructure that is resilient in a manner of sustainable development. The current understanding of green infrastructure resilience is hindered by the divergence of generic properties and performance in adapting to uncertain disturbances. This study develops an operational methodology that integrates structural and functional properties of green infrastructure, and their connections to shape the general resilience. A further empirical study is conducted in the context of Shenzhen City, where the effectiveness of resilient connections is correlated with the distribution of waterlogging. We demonstrate that green infrastructure present different levels of resilience in terms of its structural composition and functional performance. The Shenzhen city shows a high capacity to maintain soil retention stability, but a feeble capacity regarding water yield and gross primary productivity. The resilient connections of green infrastructure are highly centralized, with a few pivotal nodes performing a high degree of connectivity. It shows that a total of 52.2% of resilient lines are identified as belonging to the fourth level but linking the majority of the nodes. Enhancing the general resilience of green infrastructure could facilitate its adaptation to specific disturbances such as waterlogging. When correlated the resilient connections of green infrastructure with the distribution of waterlogging, a distance of 1.6 km from the waterlogging points is significantly identified where the residuals of the entropy index display the lowest variance. As the distance increases, the composite entropy index initially decreases and then increases. We suggest that the alignment of generic properties and specified performance of green infrastructure is essential in the pursuit of sustainable development.
JOURNAL OF NATURAL RESOURCES，2024
Hui TANG, Jian PENG, Dong-mei XU, Jian-sheng WU
Abstract:Implementing large-scale ecological restoration of territorial space is a key strategy for China to halt ecosystem degradation and promote ecological civilization. As a reference benchmark and target guide for ecological restoration, the reference of ecological restoration is a necessary basis for the smooth implementation of ecological restoration projects. However, there is little research focusing on the ecological restoration reference of terrestrial space. Aiming to know what is ecological restoration reference, what are its characteristics, and how to identify it, in this study we discussed the definition, the identification approach framework, and the directions of future research of ecological restoration reference of territorial space. This study suggested that the reference of ecological restoration of territorial space had three basic characteristics: comprehensiveness of indicators, two-dimensionality of space and time, and dynamic adaptability. The identification framework of ecological restoration reference of territorial space includes three major steps: comprehensive ecosystem assessment, reference ecosystem selection, and reference identification under integrated spatial and temporal dimensions. With the focus on the key issues of Nature-based Solutions, integrated protection and restoration of mountains, water, forests, lakes, grasses and sands, and social-ecological system sustainability, we highlighted that ecological restoration reference identification should place great emphasis on systemic thinking, take sustainability as the core orientation for the selection of reference indicators, and pay attention to the social-ecological system integrated perspective, so as to identify ecological restoration reference based on the social-ecological process and oriented to the comprehensive enhancement of social-ecological system sustainability. This study clearly defined the conceptual connotation and identification framework of ecological restoration reference in terrestrial space, and provided theoretical and methodological support for the orderly promotion of ecological restoration projects.
116.A Satellite-Based Approach for Thermal Comfort Simulation: A Case Study in the GBA
Urban Climate，July 2024
Danni Zhang, Chang Liu, Jiansheng Wu, Hongliang Wang
Abstract: With global warming, the issue of urban surface overheating has emerged as one of the most urgent concerns for modern cities worldwide. However, the simulation of thermal comfort with high spatiotemporal resolution remains a challenge. In this study, an approach is presented to integrate several global meteorological raster data for the production of high spatial and temporal resolution thermal comfort raster datasets. Our approach produced a dataset in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) covering 98.30% of diurnal moments in 5 years, and the spatial coverage of the region exceeded 87%. The assessment results showed that from 2002 to 2020, mean universal thermal climate index (UTCI) slightly increases from 16.0 to 20.6 °C to 17.3–26.2 °C, dominated by no heat stress (9.0 °C–26.0 °C). The low-value center of UTCI locates in the north GBA, around Zhaoqing and northern Guangzhou, while the high-value center moved westward from Huizhou to Foshan, Dongguan, and the south of Guangzhou. Over the past 18 years, the heat stress has become larger in the spatial extent and more prolonged. The heat island effect has intensified over the past 18 years, resulting in a coexistence of the positive heat island intensity and the negative heat island intensity. The result investigates urban thermal comfort conditions for urban thermal environment management and provides a spatial reference for human-centered urban planning.
Land，2024
Chang Gao, Yueyang Du, Yuhao Zhao, Yingqiao Jia, Jiansheng Wu
Abstract: Global warming caused by massive carbon dioxide emissions can lead to a chain of ecological disasters. As one of the main sources of carbon emissions, transportation is of great significance, and the evaluation of its connections with carbon emissions is necessary to achieve “carbon neutrality”. Taking Beijing as an example, this study evaluated traffic efficiency (TE) by utilizing principal component analysis and fuzzy comprehensive evaluation. Using the Tapio decoupling model and coupling coordination degree model, the corresponding relationship between urban low carbon level (LCL) and TE was explored. The results showed the following: (1) The total carbon emission (CE) level exhibited fluctuating variation from increasing to decreasing. The carbon emission intensity (CEI) continued to slow down, and the rapid growth of population density played a key role in low-carbon development. (2) The traffic operations continually showed a positive trend in development. TE increased from a step-like to a slow shape, until it declined in 2020 due to the pandemic. (3) TE and LCL both developed from low coordination to an extreme level of coordination. Per capita carbon emission (CEP) and TE presented an inverted U-shaped curve; meanwhile, with increases in TE, the decline in CEI slowed. In addition, the weak decoupling of TE changed to become strong, due to CE and CEP, and maintained a strong decoupling state from CEI. (4) There is a necessity for the rational planning of land use for transportation infrastructure, the encouragement of a combination of public and private transportation, and the strengthening of the maintenance of the relative infrastructure and the management of traffic behaviors to attain a win–win situation. The results provide a reference for optimizing the traffic structure to achieve “carbon neutrality”.
114.Effects of ecological control line on habitat connectivity: A case study of Shenzhen, China
Ecological Indicators，October 2024
Shengyong Zhang, Zheng Zhang , Jingqi Wang, Yiheng Zhang, Wu Jiansheng，Xiwen Zhang
Abstract: Ecological control line (ECL) has become an important policy for enhancing ecological conservation and achieving sustainable urban development. Landscape connectivity of ecological network provides a method for exploring the effect of ECL policy on biodiversity conservation. This study used Shenzhen as an example to analyze the distribution of important habitats based on species occurrence points, environmental factors and artificial neural network methods. Four-phase ecological networks of focal species (Ardea cinerea, Callosciurus erythraeus, Copsychus saularis, Egretta garzetta, Pycnonotus sinensis) in 2000, 2010, 2015, and 2020 were constructed, and the effects and changes of ECL on habitat connectivity of species, geographical zone, and species zone scales were sequently analyzed using the difference-in-difference method. The results showed that: (1) Forty-one important habitats were identified, with a total area of 743 km2, and the average area of each habitat was 18.1 km2. The number of ecological corridors and the area of ecological pinch points in Shenzhen decreased in the first ten years but remained stable over the final ten years. (2) ECL delineation can promote habitat connectivity of regional species and with the passage of time, this promoting effect increases. The protective effect in the high habitat quality zone was greater than that in the low habitat quality zone. (3) City managers can develop habitat connectivity conservation schemes for different species according to the five habitat quality zones: high, mid-high, middle, mid-low, and low. This study proposes a method to assess the effectiveness of the existing ecological control line, and provide a scientific basis for formulating, adusting and optimizing ecological management.
Frontiers in psychology，March 2023
Jianzheng Liu, Jie Li, Xiwen Zhang, Jing Song, Weifeng Li, Jiansheng Wu
Abstract:The Chinese central government has been running an intensive exchange program called the Mainland China–Hong Kong Ten Thousand Student Exchange Program since 2012 to support local Hong Kong university students’ visits to mainland China, with the aim of promoting exchange and regional cooperation between Hong Kong and mainland China. However, little is known about local Hong Kong university students’ views on regional cooperation and whether the program is effective in changing their views. Using a randomized experimental design, we find that most students hold positive views on regional cooperation between Hong Kong and mainland China, but a considerable percentage of students oppose integration with mainland China. We also find that the program is effective in positively changing students’ views on certain aspects of regional cooperation related to the free trade zones and the Hong Kong–Zhuhai–Macau Bridge, but is not significantly effective on other aspects of regional cooperation. This study provides the first causal quantitative evidence regarding the impact of the mainland China–Hong Kong exchange program on local university students’ views regarding regional cooperation. The findings help inform the public about the prospect of regional cooperation and offer policy implications on youth exchange between mainland China and Hong Kong.
112.How Does Fire Suppression Alter the Wildfire Regime? A Systematic Review
Fire，November 2023
Hai Jiaying, Zhang Ling, Gao Cong, Wang Han, Wu Jiansheng
Abstract:Fire suppression has become a fundamental approach for shaping contemporary wildfire regimes. However, a growing body of research suggests that aggressive fire suppression can increase high-intensity wildfires, creating the wildfire paradox. Whether the strategy always triggers the paradox remains a topic of ongoing debate. The role of fire suppression in altering wildfire regimes in diverse socio-ecological systems and associated research designs demands a deeper understanding. To reconcile these controversies and synthesize the existing knowledge, a systematic review has been conducted to screen 974 studies on the relationship between fire suppression and wildfire regimes. The rigorous screening process led to the selection of 37 studies that met our stringent criteria for inclusion. The selected literature was quantitatively analyzed in terms of study areas, study design and methods, and the impact of fire suppression on wildfire regimes. Several critical findings were revealed: 1. Numerous studies have focused on northern mid- and high-latitude biomes, neglecting tropical savannas where wildfires are frequent and intense. Further exploration in these regions is imperative. 2. Existing studies have predominantly employed methods such as difference analysis, regression analysis, and scenario simulations. Appropriate methods could be selected based on the study area, data availability, and understanding of fire regimes. 3. Despite the consensus that fire suppression reduces the total burned area, the emergence of the wildfire paradox remains controversial, with approximately equal amounts of the literature supporting and contradicting the wildfire paradox. A noteworthy pattern was observed: the wildfire paradox is more likely to occur in fuel-limited systems, specific vegetation types, and smaller scale and longer term studies. This systematic review highlights that the occurrence of the wildfire paradox is intricately tied to ecosystem feedback mechanisms for suppression and the research scale adopted. It is necessary to incorporate a comprehensive and multi-scale assessment of how local wildlands respond to suppression into wildfire management policy-making processes. This assessment will ensure a more informed and effective wildfire management strategy adapted to local conditions.
Science of The Total Environment,December 2023
Wang Han, Zhang Danni, Liu Songyue, Ye Sheng, Jin Xueru, Wu Jiansheng
Abstract:Unravelling the evolution of landscape patterns is essential to understand regional socioecological processes and to solve conflicts between environment protection and human development. However, the role of landscape transition in regional landscape pattern evolution remains unclear. Taking 325 county-level areas in the middle reaches of the Yangtze River (MRYR) as an example, this study explored the spatiotemporal associations between landscape quantity and pattern from the 1970s to 2020. Employing the methods of landscape metrics and trend and correlation analysis, associations between landscape transition and landscape pattern were found. The main results were as follows: (1) From the 1970s to 2020, urban land nearly doubled from 0.93 to 1.89 million km2. Arable land and forest showed the largest quantity reductions of 0.88 million km2 and 0.28 million km2, respectively. Other landscapes showed both decreasing and increasing trends with a spatial overlap among counties. (2) Transition in landscape quantity drives the change in landscape patches, thus affecting the land-scape pattern in counties. The percentage of landscape area at the class level (CPLAND) showed relative changes in the quantities of landscape categories in each observation year, but their extreme outliers presented larger changes. (3) Diverse correlation coefficients in terms of magnitude and direction suggested that the transition from natural landscape to human-influenced landscape and the reverse processes occurred. Aggregation and diversity metrics showed spatial interaction with similar distances and the perimeter-area fractal dimension (PAFRAC) showed spatial autocorrelation at local scale. Optimal bandwidths among arable land, forest, and urban land (129.2 km) revealed direct spatial interactions and causal relationships, as did waters and unused land (66.7 km). The findings explained the evolution of landscape patterns and highlighted key areas where various landscape changes occurred, and can provide scientific support for policy-making in regional landscape transition governance.
110.Key attributes of greenspace pattern for heat mitigation vary with urban functional zones
Landscape Ecology, November 2023
Wang Qi, Peng Jian, Yu Shuying, Dan, Yuzhuo, Dong Jianquan, Zhao Xiang, Wu Jiansheng
Abstract：ContextUrban green space (UGS) has been widely acknowledged to effectively reduce ambient temperature, and thus improving its cooling effect has become a hot topic in urban planning. Although the impact of UGS spatial pattern on land surface temperature (LST) has been investigated in previous studies, the differences caused by the heterogeneity of human activities within urban areas have not been fully understood.ObjectivesThis study attempted to explore different relationships between UGS spatial pattern and LST among various human activity dominated zones to effectively support urban heat mitigation.MethodsTaking the urban area within the third ring road of Changsha City as the study area, the random forest model was applied to evaluate the contribution of UGS spatial pattern on LST and partial dependence curves were generated to identify their nonlinear relationships among different urban functional zones (UFZs).ResultsIn terms of varied dominant influencing factors affecting LST, the area proportion of UGS was the most important factor in residential, industrial, campus, and public zones, which showed a negative impact on the variation of LST. The cohesion between UGS patches was also an important factor in residential zones, and the more aggregated the more conducive to cooling. UGS patch density interpreted the highest importance in commercial zones, which played a significantly negative role when less than a specific threshold. However, the influence of landscape shape complexity on LST was limited in five built-up functional zones.ConclusionsThe impact of UGS spatial pattern on heat mitigation was quite different in various UFZs. The findings can provide targeted guidance for green space planning in regard to effectively mitigating the urban heat island effect.
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