Search Results (31,522)

Assessing land use-based changes in ecosystem service values (ESVs) is a beneficial approach for land resource planning and ecologically sustainable development. Located in the south of China, Guilin is one of the first Sustainable Development Goals (SDGs) Innovation Demonstration Zones set up by China. It is a typical ecotourism city with an important ecological and economic status. In recent years, the time series, model fit, and spatial scale of ESV assessment in Guilin have needed to be improved in the context of rapid urbanization and natural change. In this study, an improved ESV assessment methodology was utilized to incorporate the effects of biomass, soil conservation, and precipitation and to adjust the equivalence factors based on the ratio of geographic and environmental parameters to the national average to make them heterogeneous in time and space in improving the practical fit of the assessment results. The study analyzed the evolution of land use and its contribution to ESVs in Guilin from 2000 to 2020. County and 3 km × 3 km grid scales were combined to reveal both broad and detailed spatial and temporal characteristics of ESVs in Guilin. The results show that the expansion of building land in Guilin is notable, and the amount of land use transfer continues to increase. ESVs fluctuated in a lateral S-shape, with significant differences in ESV effectiveness between counties, consistently high ESVs near waterbodies and ecological reserves, and low ESVs near commercial and industrial land and cultivated land. Despite the recovery trend in ESVs in the later years, there is still a gap between 2020 and 2000. To a certain extent, it helps Guilin optimize land allocation from different perspectives and promote ecological improvement and resource planning optimization. Full article

Studies have extensively examined the cooling effects of forests. Various methods exist for evaluating climate regulation at regional and global levels. Local-scale cooling effects and their valuing methods, however, remain poorly understood. In this study, the temperature difference and energy balance methods were compared to assess the value of cooling services of three forest types at a local scale. Using the window searching strategy, land surface temperature and sensible heat flux differences between forest and open land were compared. The average cooling temperature of broad-leaved forests was found to be 0.229 °C, significantly higher than that of coniferous forests, at 0.205 °C, while mixed coniferous–broad-leaved forests were not significantly different to the other two types. The average sensible heat flux differences in broad-leaved, coniferous, and coniferous–broad-leaved forests were found to be 0.23, 0.079, and 0.11 MJ/m²/day, respectively. According to the correlation analysis, the sensible heat flux was significantly correlated with the cooling degree (R = 0.33, p = 0.05), suggesting consistency between the two approaches. However, the total cooling value calculated with the energy balance method was CNY 0.51 billion, significantly higher than the temperature difference method at CNY 0.11 billion. The main reason for the differences between the two approaches is the uncertainty in cooling volume and cooling time for the temperature difference method and energy balance method, respectively. The impact of vegetation on the microclimate depends on the vegetation type, topography, local climate, and other factors. It is also important to note that cooling services are not required at all times of the day, and energy differences can hardly be calculated based on the hour. However, surface radiation and evapotranspiration generally occur during the daytime, which is also when the surface temperature is high. Therefore, there is a certain coincidence with the time when cooling is needed. The energy balance method presented herein provides a novel alternative approach to assessing the cooling services of local-scale forests, offering advantages over the commonly used temperature difference approach, which is associated with large uncertainty. Full article

The surface subsidence duration and the maximum subsidence velocity are critical indicators to evaluate the stability and severity of surface damage. Precisely predicting them is important for guiding engineering design and protecting ground infrastructure. Traditional manual measurement methods are time-consuming and laborious, and the existing empirical formulas have low accuracy and poor applicability. Therefore, a new prediction method was established in this paper. Measured data from 30 mining areas were used for verification. The results show that the predicted surface subsidence duration is basically consistent with the measured value. The standard deviation of the two is 61 d, and the relative standard deviation is 6.6%. The predicted surface maximum subsidence velocity is basically consistent with the measured value. The standard deviation of the two is 10.0 mm/d, and the relative standard deviation is 1.6%. The surface subsidence duration and the maximum subsidence velocity are positively correlated with the coal seam thickness, negatively and positively correlated with the mining speed, and positively and negatively correlated with the mining depth. The mining speed and mining depth have the same sensitivity to the two indicators, and the coal seam thickness is more sensitive to the surface subsidence duration. Furthermore, construction within the subsidence basin may further contribute to surface subsidence. Therefore, land reuse measures should be implemented following the predicted surface subsidence duration in this paper. This study addresses the knowledge gap in this field by deriving theoretical formulas for surface subsidence duration and maximum subsidence velocity. In the absence of sufficient measured data, engineers can calculate predicted values in combination with geological mining conditions and develop appropriate mining plans based on the extent of surface subsidence. Full article

Windshear is a microscale meteorological phenomenon that can be dangerous to aircraft during the take-off and landing phases. Accurate windshear detection plays a significant role in air traffic control. In this paper, we aim to investigate a machine learning method for windshear detection based on previously collected wind velocity data and windshear records. Generally, the occurrence of windshear events are reported by pilots. However, due to the discontinuity of flight schedules, there are presumably many unreported windshear events when there is no flight, making it difficult to ensure that all the unreported events are all non-windshear events. Hence, one of the key issues for machine-learning-based windshear detection is determining how to correctly distinguish windshear cases from the unreported events. To address this issue, we propose to use a positive and unlabeled learning method in this paper to identify windshear events from unreported cases based on wind velocity data collected by Doppler light detection and ranging (LiDAR) plan position indicator (PPI) scans. An optimal-transport-based optimization model is proposed to distinguish whether a windshear event appears in a sample constructed by several LiDAR PPI scans. Then, a binary classifier is trained to determine whether a sample represents windshear. Numerical experiments based on the observational wind velocity data collected at the Hong Kong International Airport show that the proposed scheme can properly recognize potential windshear cases (windshear cases without pilot reports) and greatly improve windshear detection and prediction accuracy. Full article

Forests are valuable for a wide variety of reasons, including biodiversity and carbon sequestration and storage. As such, in the U.S., various parties have proposed large-scale forest management efforts to enhance biodiversity conservation and carbon sequestration. Others, in contrast, argue that forests should not be harvested and have used legal action to prevent timber harvest on public lands. However, given that modern forests in the U.S. are reduced in extent compared to pre-settlement times, are subject to a reduced rate of natural disturbances but experience novel disturbances such as invasive pests and elevated fire risk, and are out of ecological balance due to past human activities, we suggest that active management is not only aligned with forest sustainability but necessary to conserve the maximum feasible range of forest biodiversity. In many areas of the U.S., species most in need of conservation depend on open canopy or early seral forest conditions, both of which can be created or maintained by forest harvest. We suggest that forest management for wood products simultaneously produces these needed conditions, whereas setting aside forests from management only benefits a subset of biodiversity. Although areas not subjected to forest harvest are important landscape components, active management is also needed to restore once-common forest types such as oak (Quercus spp.) woodland, mitigate invasive pests, reduce fire risk, and manage for species that need early seral or disturbed conditions, which are declining on the landscape. We document the current unbalanced conditions and the need for management with a focus on the eastern U.S. to demonstrate the issues. Full article

The problem of the contamination of soils with high background values of heavy metals has attracted increasing attention. In this paper, the contents, spatial distribution characteristics and correlations of five heavy metals in seven types of arable soils with different soil-forming matrices were analyzed by using Kriging spatial interpolation, descriptive statistics and correlation analysis to clarify the spatial distribution of heavy metals in different soil-forming matrices, and to explore the influence of parent rocks on the spatial distribution and concentration of heavy metals. The results showed that the Cd contents of the seven soil-forming parent materials exceeded the background values recorded for soils in Yunnan Province and that metamorphic rocks such as mudstone, argillaceous rock, purple rock, and carbonate rock exceeded the risk screening values. The average Pb, Cu, and As contents were lower than the background values recorded for soils in Yunnan Province and smaller than the risk screening values for agricultural land. Carbonate areas have a large area of contamination, while metamorphic mudstone areas have a relatively small percentage of contamination. The correlations of heavy metals in different soil-forming matrices varies, and the source of each element and its correlation can be further analyzed and verified by means such as the source analysis method. The results of this study are crucial for pollution prevention and the analysis of the source of heavy metal soil contamination. Full article

Widening existing bridges is an important way to meet the surge in traffic demand, which is often carried out in a way that does not interrupt traffic. To investigate the effect of traffic vibration on the compressive strength of high-strength concrete and the splitting strength of new-to-old concrete interfaces, the initial to final set time of high-strength concrete C60 was first investigated in this article. Then, the traffic disturbance parameters were determined. Later, the compressive strength of C60 concrete at different stages under traffic disturbance parameters was carried out. Finally, the splitting tensile strength of new-to-old concrete specimens at different stages with different loading modes was tested. The test results indicated that the compressive strength of the specimens vibrated for 3 h and cured for 3, 7, and 28 days was increased by 4.3%, 5.7%, and 11.9%, respectively; those of the specimens vibrated for 7 h and cured for 3, 7, and 28 days was decreased by 13.7%, 20.4%, and 19.9%, respectively; the effect traffic vibration on the compressive strength of the specimens vibrated for 5 h was not obvious. When loaded along the old and new concrete joint, the specimens cracked along the joint; the splitting tensile strengths of the specimen at different disturbed stages were significantly decreased. When loaded perpendicular to the joint, the specimens cured for 3 and 7 days still cracked along the joint, and the splitting tensile strengths of the specimen at different disturbed stages were significantly decreased; while the specimens cured for 28 days cracked in the direction perpendicular to the joint, the tensile strengths of the specimens at different disturbed stages were significantly decreased. This study can promote the widening and improvement of existing concrete highways and bridges, which can save resources and improve land use. Full article

As a crucial form of public transportation, subways are becoming essential infrastructure that cities in China increasingly prioritize for development. However, there is a lack of effective risk assessment methods for subway station and line siting. To address this gap, this paper uses the subway system in Kunming, China, as a case study, establishing a subway site risk evaluation framework (SIRE-BAF) that integrates three dimensions: balance (B), attractiveness (A), and financing mode (F). An extended NP-RV model is proposed to assess the balance (or imbalance) characteristics of subway stations based on sub-dimensions of traffic supply, land use, and urban vitality. Findings indicate that (1) the balance (or imbalance) of subway stations is distinctly distributed along the line and simultaneously exhibits a spatial pattern radiating from the urban core to the periphery. (2) Stations with high urban vitality and minimal imbalance are highly attractive and tend to face “undersupply” during operation, whereas stations with lower attractiveness are more prone to “oversupply”. A higher level of BAF coupling coordination suggests a more suitable subway site selection and lower investment risk, while lower coupling coordination indicates increased risk. (3) Excessive reliance on the “subway + real estate” model, without considering urban vitality, may lead to high vacancy rates and reduced efficiency in subway service. This paper further assesses the site selection risks for the proposed Kunming subway. This study contributes to risk assessments of existing subway operations and maintenance in Chinese cities, enhances planning rationality and site selection for proposed subways, and holds potential applicability for other cities. Full article

The activity-height distribution of radioactive particles in the stabilization cloud of a nuclear burst plays a crucial role in the radioactive fallout prediction model, serving as the source for transport, diffusion, and dose rate calculation modules. A gas-particle multiphase flow solver was developed using the OpenFOAM Computational Fluid Dynamics (CFD) library and discrete phase method (DPM) library under a two-way coupling regime to simulate the U.S. standard atmosphere of 1976 with good stability. The accuracy of the numerical model was verified through low-equivalent nuclear weapons tests, including RANGER-Able and BUSTER-JANGLE-Sugar, depicting reasonable spatio-temporal changes in cloud profiles. The initialization module of the Defense Land Fallout Interpretative Code (DELFIC) and activity-size distribution, which considered fractionation, were employed for nuclear fireball and radioactive particle initialization. Simulations indicated that the activity-height distribution of the stabilization cloud mainly concentrated on the lower third of air burst cloud caps, while settling near the burst center for surface or near-surface bursts. This study has confirmed the effectiveness of the gas-particle flow solver based on the CFD-DPM method in simulating low-equivalent nuclear clouds and enriching research on radioactive fallout prediction models. Full article

The development of synergies between rural and urban areas is one of the EU’s objectives to contribute to smart and inclusive growth. Effective governance of rural–urban links is essential for balanced development but often lacks policy coherence. This study examines the role of spatial planning and food policy integration in enhancing local food system sustainability and resilience, specifically in peri-urban areas. It investigates challenges and enablers in this integration through a Living Lab experiment in Lucca (Italy) as part of the ROBUST H2020 project. The Living Lab methodology entailed envisioning, experimenting, and experiencing phases to identify key rural–urban connections and assess governance arrangements, focusing on reclaiming abandoned land in peri-urban areas together with local stakeholders. By highlighting the strengths and limitations of a multi-year collaborative research approach, the research highlights a weak recognition of rural–urban linkages and the need for improved dialogue between rural stakeholders and urban planners. Key recommendations comprise formalising public–private partnerships and cross-sectoral projects linking agriculture with education, tourism, and landscape (e.g., agricultural parks). Full article

The rapid development of urbanization has continuously encroached on people’s living space and ecological space, leading to an imbalance in territorial spatial functions. Identifying potential land use conflicts and optimizing land use structure are conducive to carrying out territorial spatial planning rationally. In this paper, we adopt the suitability assessment method to evaluate the suitability of land for production, living, and ecological functions and then use the land use conflict identification matrix to identify land use conflicts in Donghai County and make relevant suggestions according to the intensity of land use conflicts. The results of this study show the following: (1) the areas of suitable land use zones, strong conflict zones, medium conflict zones, and weak conflict zones in Donghai County are, respectively, 58.83%, 10.62%, 26.31%, and 4.24%. (2) The spatial distribution differences in the different conflict zones could determine the pertinence of conflict mitigation and spatial planning. In the process of the urbanization of Donghai County, ecological environmental protection is still the top priority. (3) It is necessary to economically and intensively use construction land, improving its fine management level. Land use efficiency should be maximized, and the spatial distribution of national territory should be reasonably optimized while strengthening the guiding role of planning. This study addresses land conflicts from the perspective of spatial planning rather than economic behavior. It also provides significant insight into land use layout at the county level, which is exactly what China is exploring in the new era. Full article

This study focuses on the land transfer intentions of migrants and surrounding villagers in the SZ resettlement area of BS City, Guangxi. It systematically analyzes the coupling coordination relationship between migrants’ land transfer-in intentions and the land transfer-out intentions of surrounding villagers, verifying the practical value of the “Shared Land Resource Model” in the resettlement area and its surroundings. The study yields the following key conclusions: (1) there is a strong coupling between the land demand intentions of migrants and the land supply intentions of surrounding villagers, yet the actual coordination in the transfer process is limited, which constrains resource allocation efficiency and prevents land transfer from fully utilizing shared resources; (2) in the evaluation of migrants’ land transfer-in intentions, external environmental factors have the greatest influence (with a weight coefficient of 0.7877), while individual characteristics (0.0486) and psychological characteristics (0.0593) have relatively low weight coefficients, indicating that migrants primarily rely on government policy support and lack internal motivation; (3) the land transfer-out intentions of surrounding villagers are most affected by farmland resource endowment (weight coefficient of 0.3284), indicating that the quality and quantity of land resources are key factors affecting villagers’ transfer-out willingness, while individual endowment factors have the smallest impact (weight coefficient of 0.1220). Three recommendations are proposed: stimulating migrants’ intrinsic motivation to enhance livelihood autonomy, protecting villagers’ land rights to increase transfer participation, and building a systematic land resource sharing model to promote sustainable resource allocation. This study provides theoretical support for optimizing the land transfer mechanism in resettlement areas, aiming to improve land use efficiency, support the livelihood transition of migrants, and offer practical insights for land management planning in poverty alleviation and resettlement projects in other countries. Full article

Net ecosystem productivity (NEP) plays a vital role in quantifying the carbon exchange between the atmosphere and terrestrial ecosystems. Understanding the effects of dominant driving forces and their respective contribution rates on NEP can aid in the effective management of terrestrial carbon sinks, especially in rapidly urbanizing coastal areas where climate change (CC) and human activities (HA) occur frequently. Combining MODIS NPP products and meteorological data from 2000 to 2020, this paper established a Modis NPP-Soil heterotrophic respiration (R_h) model to estimate the magnitude of NEP in China’s coastal zone (CCZ). Hotspot analysis, variation trend, partial correlation, and residual analysis were applied to explore the spatiotemporal patterns of NEP and the contributions of CC and HA to the dynamics of NEP. We also explored the changes in NEP in different land use types. It was found that there is a clear north–south difference in the spatial pattern of NEP in CCZ, with Zhejiang Province serving as the main watershed for this difference. In addition, NEP in most regions showed an improvement trend, especially in the Beijing–Tianjin–Hebei region and Shandong Province, but the pixel values of NEP here were generally not as high as that in most southern provinces. According to the types of driving forces, the improvement of NEP in these regions primarily results from the synergistic effects of CC and HA. NEP changes in provinces south of Zhejiang are mainly dominated by single-factor-driven degradation. The area where HA contributes to the increase in NEP is much larger than that of CC. From the perspective of land use types, forests and farmland are the dominant contributors to the magnitude of NEP in CCZ. Full article

Mayotte is a small tropical island in the Comoros archipelago. It became recently a French department and much of its food, especially meat, is imported from abroad. The development of livestock farming is therefore a necessity. To understand the problems faced by Mahoran farmers, we organised semi-directive interviews with 15 farmers who reared cattle, sheep, goats or poultry. The first difficulty of farmers was limited access to land, especially for ruminants. This led to feed shortages. Another difficulty was the limited access to water and the poor quality of the roads to reach the farms. Poultry farmers were too dependent on importations of feed and laying hen or broiler genotypes from metropolitan France. The lack of organization for independent food productions (absence of abattoirs, cooperatives or organised markets) is also an obstacle to the development of the sector. Animal health, although not considered a major problem, has been a nuisance in the past (anthrax in cattle or salmonella in poultry). Mahoran farmers trust veterinarians or their assistants to manage health, although they complain about the high cost. Surprisingly, farmers use traditional medicine for many of their ailments, mostly based on local plants, but rarely for animals. Overall, our study reveals that larger land areas, better availability of money for investment and access to water and fodder are urgently required to improve livestock production and economic viability of farmers in Mayotte. Full article

Research investigates the transformations in production–living–ecological spaces (PLES) across diverse scenarios and their ecological effects, with the aim of offering advice for environmental preservation and long-term growth in Sichuan Province. Utilizing the PLUS model, we simulated the PLES configuration in Sichuan Province for the year 2030 and subsequently evaluated its ecological impacts using an ecological effect assessment model. The findings reveal that: (1) population and GDP are key drivers of the expansion of Industrial-Production Spaces (IMPS), Urban-Living Spaces (ULS), and Rural-Living Spaces (RLS), whereas altitude has a crucial influence on shaping the expansion of Agricultural-Production Spaces (APS), Forest-Ecological Spaces (FES), Grassland-Ecological Spaces (GES), Water-Ecological Spaces (WES), and Other-Ecological Spaces (OES); (2) significant changes in PLES are observed in Sichuan Province by 2030 across four scenarios, with notable distinctions between the production priority scenario and the other three; (3) variations in ecological quality exist among the four scenarios concerning PLES; (4) the reasons behind better or worse ecological conditions differ across scenarios. The research demonstrates that the PLUS model can effectively simulate PLES in Sichuan Province under multiple scenarios for 2030, offering various potential development pathways and their corresponding ecological effects, thereby aiding in the selection of optimal development pathways. Full article