Optimization Of Spatial Structure Research Articles

Optimizing Stand Spatial Structure at Different Development Stages in Mixed Hard Broadleaf Forests

Thinning plays a key role in regulating the stand spatial structure (SpS) to improve the development of stand quality, and the stand has different characteristics of stand structure (SS) at different growth and development stages (DSs), so it is most important to reasonably determine the stage of growth and development of the stand to optimize the stand structure. We applied the TWINSPAN two-way indicator species analysis method to classify the different development stages of mixed hard broadleaf forests. We provided a comprehensive stand spatial structure optimization model for three selected plots at different development stages, respectively, to optimize the SpS. The results demonstrated the classified DS of 29 mixed hard broadleaf plots for three forest stages: the establishment stage, competitive stage, and quality selection stage. We then applied the SpS optimization model to our three plots; the Q(x) increased by 124.04%, 333.74%, and 116.83% when compared with those with no harvest, in which, upon the removal of 10% of the trees from the three plots, the maximum RIP values were all observed. Our results indicated that the SpS optimization model could regulate the SS for different growth stages and DSs.

Research on Jinhua City Sports Facilities Planning and Urban Spatial Structure Optimization

With the increasing awareness of national fitness, the planning and management of sports venues has become the key to improving the level of urban public services. Taking the POI data of sports venues in Jinhua City as the research object, this paper analyzes the spatial distribution characteristics of sports venues in Jinhua City, traffic accessibility and its relationship with housing prices. The study found that all the sports venues in Jinhua have good traffic accessibility, and there is a positive correlation with housing prices. Among them, the average housing prices in urban public sports venues and commercial fitness and leisure venues are higher. The research results provide a scientific basis for the planning and management of sports venues in Jinhua City, and are of great significance for promoting the balanced development of sports facilities and improving the quality of life of residents.

Multi-objective optimization of forest structure for broadleaf mixed forest under different CMIP5 scenarios

Climate change is an important global research topic and one of the most pressing issues facing the world today. It significantly impacts forest distribution, species composition, stand structure, growth, and other functions, therefore, it is crucial to simulate the dynamic changes of forest structure under future climate change and develop optimized solutions to adapt to it. Combined with the various stand structural parameters, based on the equal or unequal weights of each parameter at the stand level, to establish a dynamic stand spatial structure multi-objective optimization index (L-index) under different climate changes, and to implement broadleaf mixed forest spatial structure optimization research in Yanan Forest Farm under RCP 2.6, RCP 4.5, RCP 8.5 climate scenarios after 5 years. The results indicated that the L-index showed an increase ranging from 13.8 % to 35.7 % under equal weights in different climate scenarios. Additionally, the optimal harvesting intensity ranged from 13.2 % to 20.5 %, with the highest intensity observed in the RCP4.5 climate scenario; compared to the RCP4.5 and RCP8.5 climate scenarios, the RCP2.6 scenario shows the largest trend and magnitude of change in the indicators, suggesting that the state of stand growth is more sensitive under the RCP2.6 scenario. The L-index showed an increase ranging from 13.7 % to 34.4 % under the unequal weights in different climate scenarios, in which the optimal harvesting intensity ranged from 14.6 % to 19.8 %. More importantly, it should be noted that the values of the increases in the L-index and the relative increased proportion (RIP) were both higher than those when unequal weights were employed. Moreover, it should be highlighted that the increments in the L-index and RIP were both greater than those observed when unequal weights were applied for all three plots under different climate scenarios. Overall, the adjusted the complete mixing degree index (Mc) increased, angle index (W), dominance ratio index (U), and Hegyi competition index (CI) decreased compared to before optimizing with the equal or unequal weights of the stand structural variable, which is evident that the adjustments made to the stand’s structure have resulted in a significant improvement. Thus, the multi-objective optimization for forest spatial dynamics constructed is both reasonable and effective, and it more scientific forest management under different climatic scenarios.

Navigating urban shrinkage: Spatial influencing factors and strategic priorities for urban spatial performance in Heilongjiang Province, China

In sustainable urbanization, urban spatial elements and spatial efficiency outcomes are central elements used to quantitatively analyze spatial performance. Previous studies have not focused on shrinking cities. This study establishes a spatial element indicator system from the scale-structure-connection (SSC) dimension based on the spatial characteristics of the scale paradox, structural crisis, and relational imbalance in shrinking cities. It employs geographical detectors to reveal the effective spatial influencing elements affecting the spatial efficiency of shrinking cities in Heilongjiang Province, China, for which targeted strategies are proposed. The results show that urban spatial scale has the most prominent influence on the spatial performance of shrinking cities. Among them, control of the urban land scale, allocation of resource bases, and coordination of service facilities should not be neglected. Among the SSC dimensions, economic, social, and population benefits favor the influence of a single spatial dimension, while ecological and land benefits tend to be more influenced by multiple spatial dimensions. For different spatial benefits, different responses focused on urban-scale adjustment, spatial structure optimization, and spatial connectivity enhancement should be provided to further promote the sustainability of shrinking cities.

Research on dynamic spillover effect of stock market volatility in Beijing-Tianjin-Hebei region

To enhance economic cooperation in the Bohai Sea and Beijing-Tianjin-Hebei region, China introduced the Beijing-Tianjin-Hebei integration plan in 2014. Over the past decade, coordinated development has established a solid foundation, emphasizing economic and spatial structure optimization. The region’s development has now achieved comprehensive, qualitative, and profound progress. Recognizing economic integration as crucial, this study analyzes the 2020-2023 stock data of listed firms in the region, utilizing the DY spillover index to examine sectoral volatility spillover effects, both statically and dynamically. Results reveal bidirectional, asymmetric spillovers, with heterogeneous spillover levels. Industry, raw materials, and information technology are key spillover sectors, significantly influencing others and inducing synchronization. Property and finance sectors are primarily recipients, influenced by others. Energy and communication services exhibit strong bidirectional spillovers. Volatility spillover strength is influenced by factors such as inter-sector correlation, market risk, macroeconomic changes. Studying these factors helps grasp volatility spillover patterns and understand sectoral volatility-factor relationships.

Selection of the Optimal Timber Harvest Based on Optimizing Stand Spatial Structure of Broadleaf Mixed Forests

There is increasing interest in optimizing stand structure through forest management. The forest structure influences growth and maintains the structure, promoting sustainability. Structure-based forest management (SBFM), which is based on the spatial relationships between a reference tree and its four nearest neighbors, considers the best spatial structure for the stand and promotes the development towards a healthy and stable state by selectively thinning specific trees. This management method is a scientific approach for sustainable forest management, and appropriate harvesting is the core principle of uneven-aged forest management. However, the application of this approach in the management of uneven-aged mixed stands is a challenge because their dynamics are more difficult to elucidate than those of planted or pure stands. This study presented a stand spatial structure optimization model with a transition matrix growth model for selecting suitable timber harvest during uneven-aged mixed-forest management optimization. The model was developed using three neighborhood-based structural indices (species mingling, diametric differentiation, and horizontal spatial pattern) and diameter diversity indices. The approach was applied to four broadleaf stands in the Maoershan Forest Farm of the Heilongjiang Province. The results demonstrate that optimizing the stand spatial structure with a transition matrix growth model improved the objective function values (F-index) by 23.8%, 12.8%, 14.6%, and 28.3%, and the optimal removal of trees from the stands ranged from 24.3% to 25.5%. The stand structure in the next cycle (after 5 years) was closer to the uneven-mixed state. The main conclusion of this study is that optimizing the stand spatial structure with a transition matrix growth model can improve the speed and accuracy of tree selection for harvesting in unevenly mixed forests, thus helping regulate stable and diverse forest growth.

Comprehensive strength evaluation system of commercial centres based on multi-source data: a case of Hefei central city

Urban commercial centres are the most concentrated areas of economic activity. Understanding the spatial distribution pattern and comprehensive strength of urban commercial centres is important to guide the reasonable graded allocation of urban commercial space, spatial structure optimization and sustainable development of the commercial economy. Herein, mobile phone signalling data are used to identify the functional connection between recreational and residential places and local spatial autocorrelation analysis is used to identify the 24 commercial centres in the central city of Hefei. The comprehensive strength evaluation system of commercial centres is constructed from their basic conditions and customer consumption behaviours, and their comprehensive strength indices are accordingly measured and graded. The spatial distribution characteristics of commercial centres at all levels are analysed, and optimisation suggestions are made for the whole area and region. The following conclusions are drawn from the results of this study. (1) Compared to traditional single-perspective evaluations, the developed comprehensive strength evaluation system considers supply and demand perspectives for commercial centres, providing a more holistic and accurate portrayal of the strengths of various centres within a region. (2) The current commercial centres are characterised by ‘large dispersion and small concentration’ in spatial and hierarchical distribution. (3) The commercial centres in Hefei have formed a relatively complete ‘first, second, and third level’ commercial centre system, with the first level as the core and relying on the urban road system to form a network spatial connection. (4) Most of the commercial centres are concentrated in the First Ring Road, Swan Lake in the Government Affairs District and Binhu Century Town Estate, while most areas north of the Second Ring Road and Binhu New District still lack large-scale commercial centres. This study provides a technical reference for analysing urban commercial spatial structure patterns and provides decision support for optimising the spatial layout of urban commercial service functions.

Examining the spatial networks of an urban agglomeration through the lens of multi-dimensional element flow: Evidence from western China

The Chengdu–Chongqing urban agglomeration (CCUA), as the only national-level city cluster in southwestern China, serves as a strategic support for the Yangtze River Economic Belt and an important demonstration area for promoting new urbanization in the country. The study of the networked characteristics of the CCUA contributes to a systematic understanding of its spatial connectivity patterns, optimization of spatial structure and layout, and promotion of high-quality regional development. In this study, we constructed models for traffic flow, information flow, migration flow, and composite flow to calculate the strength of connections between cities and the total flow of various elements in the CCUA. ArcGIS spatial visualization tools were used to depict the spatial connectivity patterns of the element flows within the CCUA. Additionally, social network analysis methods, including network density, centrality, and cohesive subgroups analysis, were employed to reveal the spatial network structure characteristics of the CCUA. The findings are as follows: (1) The overall structure of the cities within the CCUA is relatively loose, with significant differences in connectivity strength. It exhibits a west-strong and east-weak pattern, with Chengdu-Chongqing, Chengdu-Deyang, Chengdu-Mianyang, and Chengdu-Meishan occupying the top tier, while Zigong and Ya'an have relatively weak connections with other cities. Chengdu and Chongqing have prominent positions in the CCUA, with Chengdu having a more prominent core position compared to Chongqing, resulting in an overall hierarchical distribution of “1 + 1+7 + 7”. (2) The network density of the element flows in the CCUA is relatively low, indicating a generally weak element connectivity. The centrality of cities other than Chengdu and Chongqing is at a moderate to lower level, suggesting a weak overall resource connectivity capacity in the CCUA. (3) Most cities tend to form cohesive subgroups based on geographic proximity, while the cohesive subgroup in Chongqing is still in its early stages of development due to administrative boundaries. The research results quantitatively depict the spatial network structure characteristics of the CCUA, providing theoretical references for its development.

Inferring nonwork travel semantics and revealing the nonlinear relationships with the community built environment

The relationship between the built environment and nonwork travels reveals potential supply-demand status between urban functional facilities and diverse living travels, which provide critical indicative information for urban spatial structure optimization. Benefiting from the large-scale travel datasets, it would be possible to investigate deeper research by modeling the implied nonwork travel semantics (such as travel purposes). This study designs a framework to reveal the nonlinear relationships between the community built environment and the potential semantics of nonwork travel trajectories. First, we construct indicators to characterize the built environment of individuals’ living communities. Then, focusing on the definition of activity areas around drop-off points, latent Dirichlet allocation (LDA) is utilized to infer the implied semantics of nonwork travel. The random forest model is employed to quantify the relationships between the community built environment and nonwork travel with various semantics. The experimental results obtained with real-life datasets from Haikou, China uncover both compensatory nonwork travel derived from diverse facility accessibility and the contributions of housing attributes to travel semantic discrepancies. The findings provide scientific references for the optimization of urban spatial layouts of both functional facilities and residential communities to meet the living demands of diverse residents without long-distance intracity travel.

Crashworthiness analysis and multi-objective optimization of spatial lattice structure under dynamic compression

A spatial lattice structure is proposed to improve the structural crashworthiness and energy absorption. First, a single-cell structure is proposed via a bionic honeycomb, and then the single-cell structure is arrayed to form a spatial lattice structure. The finite element model of the spatial lattice structure for crashworthiness analysis is established. The theoretical model of the plateau stress of the lattice structure under compressive conditions is derived, and its accuracy is verified by the corresponding finite element analysis. After that, the effect of geometrical parameters of single-cell structure on crashworthiness is analyzed. Then, geometrical parameters of single-cell structure and number of single-cell in the X, Y, and Z directions are used as design variables, the mass, and overall size are used as constraints, and specific energy absorption and collision peak force are used as optimization objectives. The multi-objective crashworthiness optimization of spatial lattice structure is carried out, and the optimal lattice structure design is determined via the gray relational analysis coupling entropy weight method. The validity of the finite element model and optimal design is verified by the drop weight impact test. The crashworthiness optimization of spatial lattice structures has important guiding significance for the design of energy-absorbing structures.

Identification of Urban Clusters Based on Multisource Data—An Example of Three Major Urban Agglomerations in China

Accurately identifying the boundary of urban clusters is a crucial aspect of studying the development of urban agglomerations. This process is essential for comprehending and optimizing smart and compact urban development. Existing studies often rely on a single category of data, which can result in coarse identification boundaries, insufficient detail accuracy, and slight discrepancies between the coverage and the actual conditions. To accurately identify the extent of urban clusters, this study proposes and compares the results of three methods for identifying dense urban areas of three major agglomerations in China: Beijing–Tianjin–Hebei, the Yangtze River Delta, and the Guangdong–Hong Kong–Macao Greater Bay Area. The study then integrates the results of these methods to obtain a more effective identification approach. The social economic method involved extracting a density threshold based on the fused nuclear density of socio-economic vitality data, including population, GDP, and POI, while the remote sensing method evaluated feature indices based on remote sensing images, including the density index, continuity index, gradient index, and development index. The traffic network method utilizes land transportation networks and travelling speeds to identify the minimum cost path and delineate the boundary by 20–30 min isochronous circles. The results obtained from the three methods were combined, and hotspots were identified using GIS overlay analysis and spatial autocorrelation analysis. This method integrates the multi-layered information from the previous three methods, which more comprehensively reflects the characteristics and morphology of urban clusters. Finally, the accuracy of each identification result is verified and compared. The results reveal that the average overall accuracy (OA) of the three areas delineated by the first three methods are 57.49%, 30.88%, and 33.74%, respectively. Furthermore, the average Kappa coefficients of these areas are 0.4795, 0.2609, and 0.2770, respectively. After performing data fusion, the resulting average overall accuracy (OA) was 85.34%, and the average Kappa coefficient was 0.7394. These findings suggest that the data fusion method can effectively delineate dense urban areas with greater accuracy than the previous three methods. Additionally, this method can accurately reflect the scope of urban clusters by depicting their overall boundary contour and the distribution of internal details in a more scientific manner. The study proposes a feasible method and path for the identification of urban clusters. It can serve as a starting point for formulating spatial planning policies for urban agglomerations, aiding in precise and scientific control of boundary growth. This can promote the rational allocation of resources and optimization of spatial structure by providing a reliable reference for the optimization of urban agglomeration space and the development of regional spatial policies.

Multi-objective crashworthiness optimization of energy-absorbing box with gradient lattice structure

To improve the lightweight and crashworthiness of energy-absorbing box, an energy-absorbing box with spatial lattice structure and multi-objective optimization method are proposed. First, a novel single-cell structure is proposed, which is replicated and arranged to form the spatial lattice structure. Then, the mechanical properties of the material are tested by quasi-static and high-speed tensile tests. The finite element model of the spatial lattice structure is established, and the numerical results are verified by the drop weight impact test. Finally, four different types of approximate models are used to fit different responses, and the combination of approximate models with higher accuracy is obtained. And the multi-objective optimization of our model is carried out. The optimal design of our model is obtained based on the grey relational analysis coupling entropy weight method. Compared with the energy-absorbing box with initial lattice, the specific energy absorption of the optimal design of our model is increased from 6.23kJ/kg to 8.91kJ/kg, an increase of 43.0%, and the mass is reduced from 1.1kg to 0.798kg, a reduction of 27.4%. The results show that the optimal design of our model has the advantages of lightweight and energy absorption.

Enhancing adsorption performance and selectivity for uranium by constructing biaxial adsorption sites on eco-friendly bamboo strips

Amidoxime-based materials are currently the most promising adsorbents for sustainable extraction uranium from seawater. However, in practical applications, the strong affinity of amidoxime-based materials for vanadium seriously interferes with the extraction uranium from seawater. Herein, a novel environmentally friendly and degradable adsorbent is firstly designed through grafting animal protein on natural bamboo strips (BS). In detail, the casein hydrolysates (sodium caseinate, acid hydrolyzed casein and casein phosphopeptide) are grafted with amidoximated bamboo strips (SCAOBS, AHCAOBS and CPPAOBS) by chemical cross-linking and amide reactions to construct biaxial adsorption sites, including amidoxime and amino acid branched chains. The optimal adsorption pH of SCAOBS, AHCAOBS and CPPAOBS were 5, 7 and 7, the adsorption capacities were 186.3, 204.0 and 68.6 mg g−1, and the attenuation was 23.1%, 17.7% and 20.2% after 5 cycles, respectively. Utilizing the weavability of BS, SCAOBS, AHCAOBS and CPPAOBS adsorbents are woven and floated in the Yellow Sea Basin, exhibiting that the adsorption capacity of uranium is 0.84, 1.21 and 0.81 mg g−1, respectively, much higher than that of vanadium. Evenly, the adsorption capacity of AHCAOBS for uranium is about 15.3 times that of vanadium (0.077 mg g−1). Through DFT spatial structure optimization, there are indeed biaxial dual adsorption sites (–COOH from amino acid and C = N-OH from amidoxime groups) between amino acids and amidoxime branched chains, and even the spatial structure of biaxial triple adsorption sites (–COOH from amino acid, O = C-N from amide bond and C = N-OH from amidoxime groups) is more stable, thereby breaking this bottleneck from the vanadium interference for the amidoxime-based adsorption materials.

Construction of an ecological security pattern for the Guanzhong Plain urban agglomeration: Scale perspective and hierarchy demand

As areas of dense populations and high economic activity, urban agglomerations have driven an overall increase in economic efficiency; however, the associated ecological risks are becoming increasingly apparent. The construction of ecological security patterns (ESPs) is an important approach for ensuring the ecological security of urban agglomerations, thereby achieving coordinated development of society, economy and ecology. Previous studies on ESPs have rarely considered the demand for ecosystem services at multiple scales and have accordingly failed to accurately identify important ecological sources. Here, we propose a novel method based on multi-scale ecosystem service demand to identify ecological sources, which can more accurately identify the ecological source meeting the regional sustainable development. Selecting the Guanzhong Plain urban agglomeration (GPUA) as study area, we constructed a resistance surface by comprehensively considering natural and anthropogenic disturbances. We found high resistance areas are mainly concentrated in highly urbanized areas with Xi’an as the core. In addition, we performed minimum cumulative resistance and gravity model to obtain and classify ecological corridors. The results revealed that the ecological sources identified in this study can enhance the connectivity of the inner regions of the GPUA and the linkage between north and south ecological corridors. The ecological sources were found to be concentrated in the southern Qinling Mountains, with an area of 28,780.02 km2, accounting for 26.85% of entire region. Furthermore, we identified 121 potential ecological corridors, 47 ecological nodes, and 49 ecological breakpoints, and established that the extent of land with a high level of ecological security accounts for 21.98% of the entire regional area. This study offers a new perspective for ESPs construction, which can provide a scientific basis and policy guidance for the optimization of spatial structure and the maintenance of ecological security in ecologically fragile urban agglomerations.

Spatial structure identification and optimization path of rural regional system in urban-rural integration area: A case study of Changsha county in Hunan province

Spatial structure identification and optimization path of rural regional system in urban-rural integration area: A case study of Changsha county in Hunan province

Compound Optimization of Territorial Spatial Structure and Layout at the City Scale from "Production-Living-Ecological" Perspectives.

Land-use optimization, as an important resource-allocation method, can be defined as the process of allocating various activities to different geographic units. How to manage and control land expansion has become an urgent issue, leading a series of problems such as environmental damage and a sharp decrease in cultivated land, leading to unfavorable phenomena such as excessive urban expansion, occupation of cultivated land and important ecological spaces, and overheating of real estate development. Based on the land-use data of Wuhan city in 2020, a coupling MOP (Multi-Objective Programming) and FLUS (Future Land-Use Simulation) model was used to examine the national spatial structure and the optimization of the spatial layout. Our results showed that (1) in terms of quantitative optimal allocation, the ecological space and urban space increased, while the agricultural space greatly decreased under the three development scenarios. (2) In the simulation of spatial layout, the urban space mainly expanded vertically in the north-south direction. In the ecological space scenario, the ecological space occupied part of the cultivated land in the northeast of the city, resulting in a high degree of landscape fragmentation, which is not conducive to large-scale agricultural management. However, under optimal comprehensive benefit, part of the fragmented ecological space in the western part of Wuhan was transformed into an agricultural space. (3) A combination of the MOP and FLUS models could effectively determine land-use structure and address spatial layout optimization problems and can project space in the future urban resource configuration mode. This finding can provide a reference for the optimization of the spatial structure and layout of similar cities.

The role of subway network in urban spatial structure optimization – Wuhan city as an example

The metro transportation network in large cities is one of the most important factors affecting urban spatial structure. To further understand the role of a metro network in the optimization of an urban spatial structure, the panel data of 10 main districts in 2012, 2014, 2016, 2018, and 2020 are selected for the study of Wuhan's metro network. The influence of metro networks on the urban spatial structure is quantified by using urban spatial gravity model and social network analysis. Three indicators - overall network density, centrality, and core–edge are selected to respectively evaluate the connectivity, accessibility, and polycentricity of the spatial structure of the city. The results show that the subway construction increases the spatial connectivity by 25%, the overall accessibility by 30.33%, and the polycentricity by 7.82%. These results demonstrate that the subway construction can significantly improve the connectivity and accessibility of Wuhan’s urban spatial structure, especially the accessibility of peripheral districts, but improving polycentricity is weak. This study reveals the mechanism of action and the degree of influence of the metro network construction process on the dynamic optimization of urban spatial structure in Wuhan at different time stages from the perspective of the overall network. It provides a reference for the study of metro networks in similar cities with topographic and geomorphic diversity and enriches the research cases of such cities.

On the effective organization of rural settlements spatial structure under the transformation and development of mountainous areas in Western China: evaluation measurement based on complex adaptability theory.

The vast majority of rural settlements in Western China are located in the ecologically sensitive and diverse mountainous environment, which also experienced rapid changes in policy and institutional interventions over the past 40years. At present, in the transitional period of "post-poverty alleviation," they have more opportunities to re-integrate themselves into the large regional development. However, there is a lack of systematic evaluation and cognition of the related functions of the spatial structure between the settlements at the regional village scale and town scale. Therefore, in this paper, the theory of complex adaptive system and its analytical NK model were introduced, and a quantitative measurement framework was constructed for the adaptability level of this kind of rural settlement spatial structure organization so as to explore the effective path for its global optimization. Taking Xinglong Town of Chongqing in the western mountainous area as an example, it was found from the analysis that (1) the number of villages at a high comprehensive adaptation level has increased over time, which has an obvious positive correlation with the construction of transportation network, and a structural adsorption effect. (2) The spatial structure of the rural settlement system in the region has changed from weak industrial nodes - traffic single branch connection - public service decentralized coverage in 2010 to the organizational adaptation characteristics of stable industrial agglomeration - traffic expansion and extension - public service continuous coverage in 2019. (3) The spatial elements related to industry and public service in each village have an increasingly significant impact on the reconstruction and differentiation of its spatial structure. Finally, based on the changing trend of adaptability level and the correlation characteristics of regional space, in this paper, the spatial structure optimization strategy of Xinglong Town is put forward, which provides a reference basis for the coordinated development of the town and village space under the township-level planning in the western region.

Can the Establishment of National Key Ecological Function Areas Enhance Vegetation Carbon Sink? A Quasi-Natural Experiment Evidence from China.

The National Key Ecological Functional Areas (NKEFAs) of China rely on the main functional area planning, with the core goal of enhancing the supply of ecological products. Carbon sink is an important ecological product, and it is necessary to understand whether the establishment of NKEFAs has enhanced vegetation carbon sink (CS). Considering the establishment of NKEFAs as a quasi-natural experiment, based on the panel data of prefecture-level cities in China from 2001 to 2019, a time-varying difference-in-differences (DID) model is used to systematically examine the impact of NKEFAs on CS. The study found that the establishment of NKEFAs has significantly enhanced the CS, and compared to the non-NKEFAs, NKEFAs has increased CS in the covered areas by an average treatment effect (ATE) of 2.1625. The establishment of NKEFAs can enhance CS through the optimization of territory spatial structure, the upgrading of industrial structure and the inter-industrial mobility of labor. The enhancement roles of NKEFAs on CS are heterogeneous across different functional area types, geospatial locations, and quantile levels, with higher enhancement of CS at windbreak–sand fixation type, northwestern region and high quantiles, respectively. In addition, NKEFAs not only have a significant positive ecological spillover effect, but also balanced with local economic growth, they achieve the goals of “lucid waters and lush mountains are invaluable assets”.

The spatial pattern and influence mechanism of urban vitality: A case study of Changsha, China

In the new era, the vitality of urban space is an important engine of urban development, and the improvement of urban space vitality is the core component of urban spatial structure optimization and space renewal. However, the availability of data is an important issue in the evaluation of urban space vitality, and continuous vitality monitoring of the entire city is difficult to achieve through traditional methods of field research and questionnaire interviews. Due to this challenge, the traditional vitality assessment methods have serious limitations in the analysis of vitality causes and the guidance of urban space development. Using mobile phone signaling data, this study takes Changsha City as an example to measure the urban spatial vitality and uses the SEM model to analyze how market intervention, traffic accessibility, and spatial characteristics affect the density and stability of urban spatial populations. The results show that the overall urban space vitality density and vitality stability demonstrates an obvious “center–periphery” pattern, and the vitality of the urban center area is in a “high density–low stability” state. The overall urban vitality density on rest days is slightly lower than that on weekdays, and the stability of vitality on rest days is significantly higher than that on weekdays. Market intervention and transportation accessibility support vitality density, but not vitality stability, and spatial characteristics are the opposite. The findings can provide insights relevant to urban spatial planning and design.