Areas Of High Value Research Articles

Spatial-Temporal Variations in of Soil Conservation Service and Its Influencing Factors under the Background of Ecological Engineering in the Taihang Mountain Area, China

Soil conservation (SC) plays an important role in maintaining regional land productivity and sustainable development. Ecological engineering (EE) is being implemented in different countries to effectively alleviate the damage to the ecological environment and effectively protect soil and food security. It is important to determine whether or not the SC capacity becomes stronger after the implementation of EE and whether or not EE has a notable impact on SC in different altitude zones. The exploration of the influencing mechanism and identification of the dominate influencing factors in different geographical regions needs to be improved. In this study, the soil conservation services (SCSs) from 1980 to 2020 in the Taihang Mountain area was assessed using the integrated valuation of ecosystem services and trade-offs (InVEST) model, and the spatial and temporal distributions and influencing factors were explored. The results showed the following: (1) the average SCSs exhibited an increasing trend from 1980 to 2020 on the whole, and the rate of increase reached 50.53% during the 41-year period. The rate of increase of the SCSs varied in the different EE implementation regions, and it was significantly higher than that of the entire study area. (2) The spatial distribution of the SCSs was highly heterogeneous, and the high SCS value areas were coincident with the high-altitude areas where forest and grassland occupied a large proportion. The low value areas were mainly located in the hilly zone or some of the basin regions where the proportion of construction land was relatively high. (3) The distribution pattern of the SCSs was the result of multiple factors. The EE intensity had the strongest explanatory power for the SCSs in the hilly zone, explaining 34.63%. The slope was the most critical factor affecting the SCSs in the mid-mountain and sub-alpine zones. The slope and normalized difference vegetation index (NDVI) had the greatest interactions with the other factors in the three altitude zones, especially in the high-altitude regions. The quantitative analysis of the SCSs and the influences of EE and natural factors on the SCSs revealed the heterogeneity in the mountainous areas. These results also provide a scientific basis for the reasonable implementation of EE and sustainable management of SCSs in the Taihang Mountain area.

Correlation between Distribution of Rural Settlements and Topography in Plateau-Mountain Area: A Study of Yunnan Province, China

Topography is one of the important factors influencing the distribution of rural settlements, as the natural environment in plateau-mountain areas is more complicated and harsher and the forces of various natural influences are more obvious. Analyzing the correlation between settlement distribution and topography would help understand the influence of topography on human activities. This paper takes rural settlements in Yunnan Province as the research object, introduces the concept of the distribution index, and integrates the methods of GIS spatial analysis and mathematical statistics to analyze the correlation between them. The results show that (1) the distribution pattern of rural settlements in Yunnan Province is dense in the northeast, sparse in the northwest, dense in the middle, and sparse in the south; the overall pattern shows low density, fragmentation, and a dotted distribution of high-value areas, showing three typical core areas with very obvious spatial differentiation. (2) The distribution of rural settlements is influenced by three key topographic factors: Relief amplitude, incision depth, and surface roughness. The dispersion index of rural settlements drastically declines as the value rises. (3) Each topographic factor influences the natural resources and climatic characteristics of the region, and by coupling them with the production and life of the rural settlements and the psychological needs of the inhabitants, they form an intrinsic mechanism that influences the distribution of rural settlements. (4) Topography is an important factor when developing and constructing in plateau-mountain areas. The environmental protection and construction of human settlements should be in accordance with nature and adapted to the terrain, which can reduce the damage to the natural environment. The study provides effective data support for quantifying the relationship between the distribution of rural settlements and topography in the plateau-mountain area and optimizing the layout of rural settlements.

Spatial Differentiation of PM2.5 Concentration and Analysis of Atmospheric Health Patterns in the Xiamen-Zhangzhou-QuanZhou Urban Agglomeration.

Exploring the spatial differentiation of PM2.5 concentrations in typical urban agglomerations and analyzing their atmospheric health patterns are necessary for building high-quality urban agglomerations. Taking the Xiamen-Zhangzhou-Quanzhou urban agglomeration as an example, and based on exploratory data analysis and mathematical statistics, we explore the PM2.5 spatial distribution patterns and characteristics and use hierarchical analysis to construct an atmospheric health evaluation system consisting of exposure-response degree, regional vulnerability, and regional adaptation, and then identify the spatial differentiation characteristics and critical causes of the atmospheric health pattern. This study shows the following: (1) The average annual PM2.5 value of the area in 2020 was 19.16 μg/m3, which was lower than China's mean annual quality concentration limit, and the overall performance was clean. (2) The spatial distribution patterns of the components of the atmospheric health evaluation system are different, with the overall cleanliness benefit showing a "north-central-south depression, the rest of the region is mixed," the regional vulnerability showing a coastal to inland decay, and the regional adaptability showing a "high north, low south, high east, low west" spatial divergence pattern. (3) The high-value area of the air health pattern of the area is an "F-shaped" spatial distribution; the low-value area shows a pattern of "north-middle-south" peaks standing side by side. The assessment of health patterns in the aforementioned areas can provide theoretical references for pollution prevention and control and the construction of healthy cities.

Ecological Response to the Diluted Water in Guangxi during the Spring Monsoon Transition in 2021

Based on the field survey data of the Guangxi offshore voyage in May 2021, the distribution characteristics of the wind field during the spring monsoon transition period, the temporal and spatial changes in the diluted water path, and the corresponding ecological responses were analyzed. The results show the following: the core region of diluted water is located along the coast of Guangxi, and the diluted water expands to the east and west at the same time, where the thickness of the diluted water reaches 20 m. Under the combined action of the easterly wind and westward current, the westward expansion trend was stronger than the eastward expansion trend. The surface distribution of suspended solids, chlorophyll a, dissolved oxygen, and active silicon is similar to the dispersion range of the diluted water, and the high-value areas all appear near the estuary, which is basically consistent with the salinity distribution in the core region of the diluted water. Under the mixing caused by the wind and tide in the estuary area, the difference in dissolved oxygen between the surface and bottom layer is small, while in the nearshore area, the stratification of seawater hinders the dissolved oxygen’s downward transmission, resulting in a large difference in dissolved oxygen between the bottom and the surface.

Spatial Distribution Characteristics and Influencing Factors of Soil Organic Carbon Density in Yellow River Basin Based on MGWR Model

As the largest terrestrial carbon pool, the spatial distribution characteristics and influencing factors of soil organic carbon have important implications for global carbon cycle processes. Soil organic carbon density (SOCD) and influencing factors were predicted in the Yellow River basin using a mixed geographically weighted regression (MGWR) model based on soil organic carbon density data and environmental factors. The results showed that:① the SOCD ranged from 0-14.82 kg·m-2 and 0-32.39 kg·m-2 for the soil depths of 0-20 cm and 0-100 cm, with mean values of 3.48 kg·m-2 and 8.07 kg·m-2 and reserves of 2.76 Pg and 6.48 Pg, respectively. The high SOCD value areas were mainly located in the southern part of the Qinghai-Tibet Plateau and Loess Plateau, and the low value areas were located in the eastern part of the upper Yellow River and the inland flow area. ②Among the ecosystem types, the SOCD of soil depth in 0-20 cm was in the descending order of:forest>water body and wetland>other>grassland>farmland>settlement>desert, with mean values of 4.52, 4.31, 3.84, 3.73, 2.89, 2.78, and 2.22 kg·m-2, respectively, and the SOCD of the 0-100 cm soil depth was in the descending order of:water bodies and wetlands>forest>other>grassland>farmland>settlement>desert, with mean values of 9.58, 9.58, 8.85, 8.66, 7.07, 6.81, and 5.29 kg·m-2, respectively. The SOCR in descending order was:grassland>farmland>forest>desert>water bodies and wetlands>settlement>others, with 1.40, 0.60, 0.47, 0.11, 0.07, 0.06, and 0.05 Pg at a soil depth of 0-20 cm and 3.31, 1.49, 0.99, 0.26, 0.17, 0.14, and 0.12 Pg at a soil depth of 0-100 cm, respectively. ③ The main factors affecting the SOCD distribution were intercept, profile curvature, NDVI, and precipitation; in addition, curvature and silt also had important effects on the deep SOCD distribution in the Yellow River basin. Among the ecosystem types, precipitation and NDVI were the main factors affecting the SOCD distribution. The intercept also had important effects on the SOCD distribution in the all ecosystems except forests, whereas curvature and silt only had important effects on deserts and other ecosystems. These results revealed the spatial distribution of SOCD, influencing factors, and SOCR in the Yellow River basin and can provide a scientific basis for carbon balance, soil quality evaluation, and ecological management restoration and consolidation in the region.

Comparative Analysis of Temporal-Spatial Variation on Mountain-Flatland Landscape Pattern in Karst Mountainous Areas of Southwest China: A Case Study of Yuxi City

Taking Yuxi City, a typical mountain-flatland in the southwestern karst mountainous area, as an example, we used six remote sensing images from 1995 to 2018 as the main data sources, and the grid scale was used to calculate the landscape pattern index in order to analyze the temporal-spatial evolution characteristics of the landscape pattern. The results are shown as follows: (1) At the class level, most landscape indices and fragmentation degrees of landscape units in the flatland area are significantly higher than those in the mountainous area. The layout of construction land and cultivated land is also more concentrated than that in the mountainous area, but the central tendency of forest and grass in the mountainous area is more eye-catching. (2) At the landscape level, although the landscape diversity index and landscape shape index of both the mountainous areas and the flatland areas decrease in the low-value area and increase in the high-value area, the proportion of high-value areas in the flatland area is noticeably greater. The proportion of the high-value areas of the largest patch index in the mountainous area is significantly greater, and in the flatland area, the low-value area continues to expand while the middle and high value areas continue to shrink. (3) The landscape shape of the flatland area is becoming more complex, and the landscape units in the mountainous area tend to be single. The natural landscape of forest and grass in the mountainous area continues to expand and tends to be contiguous, while the man-made landscape in the flatland area continually increases and shows fragmentation, reflecting the pattern characteristics formed by the coupling evolution of land use between two regions. The urban expansion and the increase in the construction land in the flatland area are mutually causal with the decrease in cultivated land and the increase in forest and grass in the mountainous area.

Spatial Heterogeneity and Scale Effects of Transportation Carbon Emission-Influencing Factors-An Empirical Analysis Based on 286 Cities in China.

In order to scientifically evaluate the characteristics and impact outcomes of transportation carbon emissions, this paper uses the panel statistics of 286 cities to measure transportation carbon emissions and analyze their spatial correlation characteristics. Afterwards, primarily based on the current research, a system of indicators for the impact factors of transportation carbon emissions was established. After that, ordinary least squares regression, geographically weighted regression, and multiscale geographically weighted regression models were used to evaluate and analyze the data, and the outcomes of the multiscale geographically weighted regression model were selected to analyze the spatial heterogeneity of the elements influencing transportation carbon emissions. The effects exhibit that: (1) The spatial characteristics of China's transportation carbon emissions demonstrate that emissions are high in the east, low in the west, high in the north, and low in the south, with high-value areas concentrated in the central cities of Beijing-Tianjin-Hebei, the Yangtze River Delta, the Guangdong-Hong Kong-Macao region, and the Chengdu-Chongqing regions, and the low values concentrated in the Western Sichuan region, Yunnan, Guizhou, Qinghai, and Gansu. (2) The spatial heterogeneity of transportation carbon emissions is on the rise, but the patten of local agglomeration is obvious, showing a clear high-high clustering, and the spatial distribution of high-high agglomeration and low-low agglomeration is positively correlated, with high-high agglomeration concentrated in the eastern region and low-low agglomeration concentrated in the western region. (3) The effects of three variables-namely, GDP per capita, vehicle ownership, and road mileage-have a predominantly positive effect on transportation carbon emissions within the study area, while another three variables-namely, constant term, population density, and number of people employed in transportation industry-have different mechanisms of influence in different regions. Constant term, vehicle ownership, and road mileage have greater impacts on transportation carbon emissions.

Undetected but Widespread: the Cryptic Invasion of Non-Native Cattail (Typha) in a Pacific Northwest Estuary

The early detection of invasive species is an important predictor of management success. Non-native narrow-leaved cattail (Typha angustifolia) has been detected in the Fraser River Estuary (FRE) in recent decades, but questions around their degree of establishment, and the potential emergence of hybrid cattail (Typha × glauca), remain unanswered. This study models the current and potential future distribution of non-native cattail in the FRE using a combination of spectral imagery analysis and species distribution modeling. Contrary to our expectation, we find that non-native cattails are widespread, currently occupying approximately 4 or 50 ha of FRE tidal marshes. Though never formally recorded in the estuary previously, T. × glauca appears to be the more abundant taxon, suggesting heterosis may be facilitating this invasion. We describe these taxa as cryptic invasive species, as their resemblance to native cattail (Typha latifolia) likely inhibited their detection. In our species distribution model, we distinguish between site suitability (ability to establish and persist) and susceptibility (risk of colonization when suitable). Our model predicts the scale of this invasion may increase over time, as 29% and 20% of the estuary has moderate or high suitability and susceptibility probabilities, respectively, while 16% and 24% of these habitats are currently occupied. Estuary-wide containment and eradication are unlikely given the extent of this invasion. Consequently, we recommend management prioritize monitoring and early eradication in areas of high conservation and cultural value. This study highlights the vulnerability of estuaries to cryptic invasions and the invasibility of Pacific Northwest estuaries by non-native cattail.

Prediction of hydrocarbon source rock distribution using logging curves: A case study of Es32 source rock in Nanpu Sag, Huanghua depression, Bohai Bay Basin

The Es3 is the main hydrocarbon source rock system in the Nanpu Sag. Finally, the TOC and hydrocarbon potential of each sub depression of Es3were predicted. The study shows that the hydrocarbon source rocks of Es32 and Es34 sections are mainly of type II2 and type II1 respectively, with good organic matter type and high maturity. Biomarker compound parameters indicate that the Es32 section hydrocarbon source rocks developed in a semi-saline, low to medium terrestrial source organic matter supplied reduction environment with a high algal contribution; the Es34 section hydrocarbon source rocks formed in a freshwater, low terrestrial source supplied reduction environment with a medium-high algal contribution. The multiple linear regression method is more effective than the ΔlgR method in predicting hydrocarbon source rocks in the Nanpu Sag, and the prediction accuracy is higher; the correlation between TOC and S1 + S2 is the best in the model for predicting hydrocarbon potential. The TOC and hydrocarbon potential of the hydrocarbon source rocks in Es31 are generally low; the high value area of TOC and hydrocarbon potential of the hydrocarbon source rocks in Es32 is partly between the No. 1 tectonic zone and No. 5 tectonic zone in Linque sub depression, and the TOC and hydrocarbon potential of the hydrocarbon source rocks in Liunan sub depression are larger; the high value area of TOC and hydrocarbon potential of the hydrocarbon source rocks in Es34 is mainly concentrated in Shichang sub depression.

The Spatio-Temporal Variability in the Radiative Forcing of Light-Absorbing Particles in Snow of 2003–2018 over the Northern Hemisphere from MODIS

Light-absorbing particles (LAPs) deposited on snow can significantly reduce surface albedo and contribute to positive radiative forcing. This study firstly estimated and attributed the spatio-temporal variability in the radiative forcing (RF) of LAPs in snow over the northern hemisphere during the snow-covered period 2003–2018 by employing Moderate Resolution Imaging Spectroradiometer (MODIS) data, coupled with snow and atmospheric radiative transfer modelling. In general, the RF for the northern hemisphere shows a large spatial variability over the whole snow-covered areas and periods, with the highest value (12.7 W m−2) in northeastern China (NEC) and the lowest (1.9 W m−2) in Greenland (GRL). The concentration of LAPs in snow is the dominant contributor to spatial variability in RF in spring (~73%) while the joint spatial contributions of snow water equivalent (SWE) and solar irradiance (SI) are the most important (>50%) in winter. The average northern hemisphere RF gradually increases from 2.1 W m−2 in December to 4.1 W m−2 in May and the high-value area shifts gradually northwards from mid-altitude to high-latitude over the same period, which is primarily due to the seasonal variability of SI (~58%). More interestingly, our data reveal a significant decrease in RF over high-latitude Eurasia (HEUA) of −0.04 W m−2 a−1 and northeastern China (NEC) of −0.14 W m−2 a−1 from 2003 to 2018. By employing a sensitivity test, we find the concurrent decline in the concentration of LAPs in snow accounted for the primary responsibility for the decrease in RF over these two areas, which is further confirmed by in situ observations.

Understanding the Relationships between Landscape Eco-Security and Multifunctionality in Cropland: Implications for Supporting Cropland Management Decisions.

Cropland is an essential strategic resource, for which landscape ecological security and multifunctionality evolution are related to regional stability and sustainable social development. However, few studies have explored the spatial heterogeneity of the coupling between the two from a multiregional and systematic perspective, and the interaction mechanisms have still not been thoroughly analyzed. In this study, a typical karst trough and valley area in the mountainous regions of southwest China was selected as the research object, and by establishing a multi-indicator evaluation system using a landscape pattern index, a multifunctional identification model, a coupled coordination model, and a geodetector model, the spatial variability in the evolutionary characteristics and the coupling and coordination of cropland landscape ecological security (CLES) and cropland multifunctionality (CM) in the mountainous regions of the southwest and their driving mechanisms were explored. The main results were as follows: (1) CLES in the mountainous areas of southwest China has undergone an evolutionary process of first declining and then slowly rising, with the characteristics of "fast declining in the high-value areas and slow rising in the low-value areas", while CM showed a spatial distribution of "high in the northwest and low in the northeast", with positive contributions originating from ecological functions. (2) Over the 20 years, the cropland coupling coordination degree (CCCD) values showed significant spatial heterogeneity, which was regionally expressed as ejective folds (EF) > TF (tight folds) > TLF (trough-like folds) > AF (anticlinorium folds). Low CCCD values were primarily found in the east, whereas high levels were primarily found in the west, with a rapidly diminishing trend. (3) There were differences in the driving mechanisms of CCDD in different landscapes, but GDP was still the determining factor and had a limiting effect. Hence, we call for the adoption of a "function over pattern" approach in areas with more development constraints and a "pattern over function" approach in areas with fewer development constraints. Ultimately, this study will contribute to the formation of a coupled cropland mechanism system described as the "multi-mechanisms drive, multi-elements integrated" system. In conclusion, this study can provide a better understanding of the relationship between cropland patterns and multifunctionality, which can help provide a basis for cropland conservation and landscape planning in similar mountainous areas and promote the achievement of sustainable agricultural development goals in the mountainous areas of southwest China.

Land‒atmosphere coupling effects of soil temperature and moisture on extreme precipitation in the arid regions of Northwest China

With global warming and more frequent extreme precipitation events in recent years, the phenomenon of warming and humidification in the arid regions of Northwest China (ANWC) has attracted increasing attention. We assessed the coupling effects of soil temperature and moisture on extreme precipitation in the ANWC by using daily precipitation data from CN05.1 and monthly data on soil temperature, soil moisture, and energy from ERA5-land, 1961–2018. After logical partitioning by K-means clustering, the primary influencing routes in each partition were investigated using two indices of extreme precipitation, indicated by precipitation on very wet days (R95P) and the number of extreme precipitation days (R10day). We found that 1) Local extreme precipitation has had a steadily growing impact on overall precipitation. In summer, this impact is primarily driven by an increase in the quantity of extreme precipitation, but in winter, it is primarily driven by an increase in the intensity of single precipitation. 2) The Tianshan Mountains (TM) and Qilian Mountains (QM) are the key locations for the coupling of soil temperature and moisture with the extreme precipitation index. Both locations exhibit a positive coupling state for soil temperature with extreme precipitation with positive coupling in the TM but negative coupling in the QM for soil moisture with extreme precipitation. 3) In the coupling of soil temperature and moisture with energy, the relevant significant regions are almost all over the ANWC throughout the year and all seasons, and the coupling high-value areas are concentrated around the basin. 4) In the TM–Hami Basin (HB)–QM, the coupling between energy and the extreme precipitation index is also stronger. The specific coupling paths have been changing with seasonal and regional changes.

Multi-Source Data-Based Evaluation of Suitability of Land for Elderly Care and Layout Optimization: A Case Study of Changsha, China

This paper constructs an evaluation index system for the suitability of community home and institutional elderly care land development, respectively, from different elderly care modes with the data of urban POI, OSM road network, and expert questionnaires in Changsha urban area in 2021, in order to alleviate the pressure of insufficient land for elderly care brought on by the increasingly serious aging problem. The suitability evaluation index system is based on the intersection of Thiessen polygons with the current elderly care facilities as the center point as the supplementary land for the elderly and explores the optimization path of the land for the elderly in combination with the existing residential land in Changsha. The results show the following: ① The spatial variation of land suitability for both community home and institutional elderly facilities is significant, exhibiting a pattern of “high in the middle and low in the surroundings, with high-value areas clustered in the center of the city, decreasing in suitability toward the periphery, and occasional scattered clusters in the suburbs.” Among them, Furong District has the highest proportion of suitable areas for the elderly; ② Utilizing Changsha’s Tianxin and Yuhua districts as case studies, the optimal path of land use for the elderly are investigated to provide a foundation for land use planning for the elderly in Changsha.

Unraveling the Variation Pattern of Oncomelania hupensis in the Yangtze River Economic Belt Based on Spatiotemporal Analysis

The construction of the Yangtze River Economic Belt (YEB) is a great national economic development strategy in China. As the YEB covers most endemic provinces of schistosomiasis japonica featured by low endemicity, this study aimed to investigate the spatiotemporal distribution pattern of Oncomelania hupensis (O. hupensis), which serves as the only intermediate host of Schistosoma japonicum in the YEB. Annual data reflecting the distribution of O. hupensis from 2015 to 2021 were collected from the National Institute of Parasitic Disease, Chinese Center for Disease Control and Prevention. Spatial autocorrelation analysis, hotspot analysis and space-time scan analysis were performed to explore the aggregation features and spatiotemporal dynamics of the snail distribution. The distribution of both total snail habitats (during 2015-2021) and emerging snail habitats (in 2016, 2018 and 2020) showed spatial autocorrelation (Z = 15.8~16.1, p < 0.05; Z = 2.3~7.5, p < 0.05). Hotspot (high-value areas in space) counties were mainly clustered in the alluvial plain of the middle and lower reaches of the YEB. Eight spatial and temporal clusters of snail habitats were scanned and were mainly concentrated in the counties of Anhui, Jiangxi, Hubei, Hunan and Jiangsu provinces along the Yangtze River. The YEB carries a tremendous burden of O. hupensis. Surveillance and risk identification based on the snail presence should be strengthened to provide reference for protecting humans and public health security in the YEB.

Regional Differences in the Quality of Rural Development in Guangdong Province and Influencing Factors

Achieving rural revitalization is the aim of building a strong modern socialist country. However, regional heterogeneity exists in rural development in general, and studying regional differences in rural development quality is an important prerequisite for developing specific policies for rural revitalization. This paper takes 20 prefecture-level cities in Guangdong Province as the research objects and constructs a rural-development-quality-evaluation system based on four dimensions: industrial revitalization, rural affluence, social development, and environmental livability; combines the entropy value method, hierarchical analysis method, and TOPSIS to complete the evaluation process; uses a spatial autocorrelation model and cold–hot spot analysis to explore the characteristics of regional heterogeneity of rural development in Guangdong Province; and relies on stepwise regression analysis to clarify the main influencing factors. The results show the following: (1) The average value of rural development quality in the province is 0.342, with “high in the middle and low in the surrounding area” as the main spatial characteristic. (2) The average value of environmental livability dimension is 0.580, and the high-value area is found in the northeastern part of the province. There is an outer circle distribution structure with Dongguan City as the core of the high-value area, and the score gradually decreases outward, while the average value of all other dimensions is less than 0.350. The mean value of all other dimensions is less than 0.350. (3) The social development dimension shows a cold–hot spot distribution of “hot in the northeast and low in the middle”, the rural development quality and other development dimensions show a cold–hot spot spatial pattern of “high value gathering in the middle and low value gathering in the northeast”, and there is no cold spot gathering in the environmental livability dimension. (4) The average collective assets and the construction rate of science-based communities are the main driving factors of rural development, while the coverage rate of service institutions and the Engel coefficient are the main hindering factors. This paper enriches the rural development level measurement system, clarifies the spatial differentiation and main influencing factors of rural development in Guangdong Province, and helps to provide scientific support and a theoretical basis for the differentiated promotion of rural revitalization.

Cause analysis of the extreme hourly precipitation and its relationship with the urban heat island intensity in Shenyang, China

Based on the hourly temperature and precipitation data from China national meteorological stations and regional automatic weather stations in Shenyang, the relationship between extreme hourly precipitation (ExHP) and urban heat island Intensity (UHII) is analyzed. Results show that the UHII is higher at night and in the early morning. The ExHP events mostly occur at night in summer when the UHII is relatively high. The spatial distribution of UHII in Shenyang is consistent with the economic development and the transportation density. Denser population and transportation, and high-rise buildings in the urban center contribute to higher UHII. There are three types of ExHP, namely the abrupt-type ExHP, the growing-type ExHP and the continuous-type ExHP. The overall variation characteristics of the three types of ExHP are relatively consistent. Their UHII values are positive and relatively stable in 6–12 h before the start of ExHP. The UHII begins to increase dramatically about 6 h before the ExHP, but decreases obviously and turn negative after the precipitation begins. Before the abrupt ExHP, the UHII is relatively high and can rapidly return to positive after the ending of ExHP. The UHII of the abrupt-type ExHP is remarkably larger than that of the growing-type and continuous-type ExHP. The UHII before and after the abrupt-type ExHP differs greatly. Before the abrupt ExHP, the UHII is high in the center and low at both ends, and the high-value areas of UHII are mainly located in the urban area. After the abrupt-type EXHP, the UHII drops and turn negative in the whole area. The UHII is obviously increasing with urbanization. The diurnal variation of UHII is enormous, which is higher at night than during the daytime. The increasing UHII can cause abnormal air pressure in cities and villages. The air in the lower atmospheric layer of the city can be heated and expanded, hence resulting in lower local air pressure. Then, the lower air pressure can promote the convergence and upward movement of air, hence facilitating the establishment of UHII circulation. This phenomenon is particularly distinct at night, which is conducive to the occurrence of ExHP events.

Ecosystem Service Synergies Promote Ecological Tea Gardens: A Case Study in Fuzhou, China

Exploring the trade-off/synergy among ecosystem services (ESs) of agroecosystems could provide effective support for improving agricultural resilience for sustainable development. The construction of ecological tea gardens is emerging, aims to achieve a win-win situation for the tea industry and ecological environment protection. However, the effect of ES trade-offs/synergies on tea production is still not clear. In this study, we selected Fuzhou city, China, as a case study and explored the relationship among tea production and ESs in 2010 and 2020. Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) and Intelligent Urban Ecosystem Management System (IUEMS) models were used to assess the ecosystem (dis)services, which were tea production, water yield, soil retention, net primary productivity (NPP), climate regulation, soil erosion and carbon emissions. Then, the sum of trade-off/synergy coefficients of ESs (Cts) were defined to reveal the trade-off/synergy in tea gardens and areas except tea gardens (ETG areas). K-means clustering was used to assess the spatiotemporal change of traditional tea garden and ecological tea garden, reflecting the effect of ecological tea garden construction. The results showed that: (1) the high-value areas of tea production were mainly distributed in Lianjiang County, with yields up to 3.6 t/ha, and the low-value areas in Yongtai County, with yields from 0.1–1.0 t/ha. Other ESs showed spatial heterogeneity. (2) The trade-offs in ETG areas intensified from 2010 to 2020, with Cts decreasing from −0.28 to −0.73, and the synergy in tea garden was at risk of decline, with Cts decreasing from 4.46 to 1.02. (3) From 2010 to 2020, 96.72% of traditional tea gardens (Area I) were transformed into ecological tea gardens (Areas IV and V). (4) Further, we classified the tea garden into five zones based on tea yield, with Zone I as the low tea yield areas and Zone V as the highest. From Zone I to Zone V, the Cts increased from 2.6 to 7.5 in 2010, and from 1.9 to 6.5 in 2020, respectively. These results demonstrate the effectiveness of the construction of ecological tea gardens in Fuzhou and provide a reference for subsequent studies on the ESs of tea gardens and governance of ecological tea gardens.

Ecological compensation in the Beijing-Tianjin-Hebei region based on ecosystem services flow

Under a background of unbalanced regional economic development and ecological environments, the accurate identification of ecological compensation (EC) areas and the determination of compensation standards have become research key and hotspots. Their aim is to improve the long-term mechanisms of interregional EC. In this study, ecosystem services value (ESV) in the Beijing-Tianjin-Hebei region (BTH) in 2000, 2010 and 2019 are calculated using modelling and ecological economics methods. The region is divided into ecological output and input areas according to ecosystem services supply and demand. The breakpoint formula and field strength model are introduced to reveal the characteristics of ecosystem services flow (ESF) from output areas to input areas. By integrating a transfer correction coefficient system of natural, economic and social factors, an EC model based on ESF is constructed, and EC amounts for the BTH are calculated. The results are as follows: (1) The ESV of the BTH shows an increasing trend, with little change in spatial distribution characteristics. The high-value areas are distributed in the Taihang and Yanshan Mountains and Bashang Plateau in the northwest, while the low-value areas are concentrated in the Southeast Hebei Plain. (2) ESF mainly occurs in the western and northern regions of the BTH. Output areas are mainly distributed in the Taihang and Yanshan Mountains and Bashang Plateau, and their number is increasing. The flow radius, flow intensity and ESV transfer amounts also show increasing trends. (3) The ratio of EC paid by Beijing, Tianjin and Hebei is 1:0.2:2.56, the EC amounts are all provided to the Hebei Province, and the funds mainly flow to Chengde City, Zhangjiakou City and Baoding City. The proposed EC model based on ESF provides a basis and reference for the construction of an inter-regional EC mechanism in the BTH.

Response of habitat quality to urban spatial morphological structure in multi-mountainous city

Revealing the relationship between urban spatial morphological structure (USMS) and habitat quality (HQ) is of great significance for high-quality urban development. In this study, the central urban area of a typical multi-mountainous city (Guiyang, China) was taken as research area. Two-dimensional (2D) and three-dimensional (3D) characteristic indicators system of USMS was constructed. The InVEST model was used to evaluate the HQ in the study area, and the spatial pattern characteristics of USMS and HQ in the multi-mountainous city were analyzed. Finally, the response relationship of HQ to USMS was revealed through Pearson correlation analysis and curve fitting. The results showed that: (1) The average level of HQ in the study area is low and the spatial aggregation effect is obvious; the spatial distribution difference between the high value area and the low value area is significant; the high value area is mainly distributed in the area where the large area of urban green space (UGS) and the urban remnant mountains (URMs) are located, while the low value area is mainly distributed in the high-intensity urban construction area. (2)The URMs have a significant impact on the USMS within the city, the intelligibility(I), spatial permeability, spatial aggregation degree, and spatial traffic attraction potential were poor; the buffer zone within 4 km of the urban center is the core area of urban development, and the buffer zone within 15 km is the rapid urban development area. (3)Among the USMS indicators, Choice(C) was significantly positively correlated with the HQ, while the Connectivity(Con), I, Average height(AVH), and Otherness(O) were significantly negatively correlated with the HQ. (4)Stepwise regression results showed that USMS could explain the difference of HQ in the study area well, and the values of fitting coefficient R2 were 0.975, 0.837 and 0.945 in 2008, 2013 and 2018, respectively. (5)There was a quadratic function relationship between HQ and USMS principal component factor f, and there was a threshold effect, and the thresholds were 0.798 in 2008, 0.905 in 2013 and 0.474 in 2018, respectively. This study confirmed the response relationship of HQ to USMS and demonstrates the existence of a threshold, which has important reference significance for urban biodiversity conservation and high-quality urban development.

How does population aging affect urban green transition development in China? An empirical analysis based on spatial econometric model

Population aging plays a crucial role in urban green transformation development, and it is of great theoretical and practical significance to clarify the relationship between the two. Based on systematically sorting out the connotation of green transformational development (GTD), this study constructed a framework system for urban GTD, measured the GTD performance of 284 prefecture-level and above cities in China using the EW-TOPSIS model, and further explored the impact effects and mechanisms of population aging on urban GTD in China using the ESDA method, the spatial Durbin model and the mediating effect model. The main findings are as follows. (1) The average urban GTD performance in China from 2009 to 2019 showed a steady upward trend, but was still at a low level. Overall, the spatial distribution pattern of GTD performance showed the characteristics of “south > north” and “east > west”, mainly showing the evolution characteristics of the Yangtze River Delta city cluster, the Pearl River Delta city cluster, and the Beijing-Tianjin-Hebei city cluster as the core high-value areas gradually decreasing outward. (2) The impact of population aging on urban GTD had nonlinear and spillover characteristics, that is, population aging also impacted urban GTD in surrounding areas. Specifically, the increase of population aging in a city had a significant “U” shape effect on the GTD of that city, but the effect on the GTD of neighboring cities had an inverted “U” shape effect. (3) In terms of impact mechanism, population aging positively affected urban GTD by increasing human resources and technological innovation, while the transmission path of reducing labor supply had not yet come into play. Finally, according to the research findings, targeted recommendations are put forward.