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Research on surface water (SW) dynamics is important for understanding climate change and the impacts of human activities on water resources. This article assesses the extent and direction of SW changes in the Pearl River Delta (PRD). Landsat images were used to determine the area of SW based on the modified normalized difference water index (MNDWI); the center of gravity was used to map the shifting distribution of SW dynamics; and landscape indices and potential causes of the observed SW changes were explored. Although the PRD has experienced high‐intensity economic development for 30 years, the total SW areas in 1988, 1998, 2008, and 2018 were 2,608, 3,154, 3,521, and 3,613 km2, respectively. The center of gravity of SW was in Shunde, Foshan (FS), which exhibited a trend of westward expansion. Over time, the landscape pattern of SW in the PRD became increasingly fragmented, and its shape tended to be complex. The growth of fish ponds was the most obvious change, as illustrated by the increase in aquatic product production. These and other findings highlight the importance of patterns, structures, and policies in SW dynamic analyses. Wetland and agricultural policies will likely cause the maintenance or continued expansion of SW areas. [ABSTRACT FROM AUTHOR]

• ESDA was applied to estimate the pattern of ecological security (ES) in PRD, China. • Hot and cold spots for the spatial distribution of ES were identified. • Optimal management was proposed from three categories for each municipality. • The main factors influencing ES distribution were explored using semivariance. The ecological security (ES) pattern in China is gaining considerable attention worldwide due to intensifying urban development and human activities that threaten ecosystem structures and ecological processes. The Pearl River Delta (PRD) has experienced intense economic development for nearly 40 years; however, the ES pattern in the PRD is poorly understood. In this paper, we used a multisource data approach to assess ES, performed downscaling to a 1 × 1 km2 grid size, and applied spatial statistics to analyze the ES pattern in the PRD. We found three natural "ecological buffers," namely, nature reserves and forest patches covering several municipalities in the delta, thus guaranteeing the socio-economic development of this highly urbanized area. The spatial autocorrelation results indicated that the ES pattern is significantly spatially correlative (p = 0.001), with a Moran's I of 0.7766. We identified several hot and cold spots for the ES spatial distribution that occupied 58.49% of the PRD's total area. Moreover, a semivariance analysis showed that structural factors are dominant in the ES spatial distribution. Based on the ES area proportions, the 9 municipalities of the PRD can be grouped into three categories: optimized development zones, comprehensive development zones, and ecological conservation development areas. Zhaoqing, Huizhou and Jiangmen are key areas for improving ES conservation in the PRD. In this study, we explore an ES assessment model coupled with a spatial heterogeneity analysis to provide insights into ecological conservation efforts in urban agglomerations. [ABSTRACT FROM AUTHOR]

Since 2000, the gross domestic product (GDP) of the Pearl River Delta (PRD) has increased by more than eight‐fold. Experiences throughout the world indicate that the impacts of economic development on vegetation are particularly important. This study analyzed the variations in vegetation coverage in the PRD from 2000 to 2016. Moderate resolution imaging spectroradiometer normalized difference vegetation index (NDVI) data were employed, whereas climate data, GDP, and population were also used as influencing factors. Topographic factors were introduced to explain the spatial vegetation patterns, and the impacts of human activities on vegetation were explored. The results revealed (a) the overall vegetation coverage in the PRD showed an increasing trend, and the overall average NDVI increased by 0.0033/a. (b) The spatial pattern did not change greatly, but the high and low NDVI values moved to low elevations and shallow topographic slopes where human activities were prevalent. This trend resulted in increased NDVI values in 38% of the area of the PRD (p < 0.01). (c) There was a positive correlation between NDVI and economic growth (GDP, population), with correlation coefficients greater than 0.8 (p < 0.01). NDVI is influenced by climate change and human activities (such as afforestation, resident lifestyles, and economic development policies). This study reveals that with good policies, both rapid economic development and vegetation coverage improvements can be simultaneously achieved in a region. The findings of this study are crucial for the sustainable development of the mega‐urban agglomerations of the PRD and Guangdong‐Hong Kong‐Macau Grand Bay. [ABSTRACT FROM AUTHOR]

• Relationships between ecosystem services and urbanization were assessed. • Ecosystem services were significantly correlated with urbanization. • Different ecosystem services showed varied responses to urbanization. • Most developed urban areas had the lowest regulating and supporting services. • Relationships between ecosystem services and urbanization remained robust. Research on the relationship between ecosystem services (ESs) and urbanization has been drawing attention in recent years. We analyzed the relationship between ESs and urbanization in the Pearl River Delta (PRD) region, and explored whether and how this relationship changes across temporal and spatial scales. The InVEST model was used for ESs mapping and various urbanization indicators were selected. Correlation analysis and curve estimation were used to detect the linear and nonlinear relationships between ESs and urbanization. Results of the study indicated that regulating and supporting services decreased, while provisioning services increased with urbanization. Significant correlations (p ˂0.05) were found between ESs and urbanization, and mostly presented an increasing trend from 2000 to 2018 and from the grid scale to the county scale. Curve estimation indicated that regulating and supporting services decreased as urbanization increased, and water yield service increased as urbanization increased, while the relationship between food provisioning and urbanization presented an inverse-U shape. Generally, the relationships between ESs and urbanization varied with different ESs but remained relatively robust across time and scale. This study specifies the impact of urbanization on ESs, and highlights the importance of spatial scales in studying the relationship between urbanization and ESs. [ABSTRACT FROM AUTHOR]

Analyzing the distribution of air pollution and its influencing factors is critical for regional air pollution prevention and control. This study takes the Pearl River Delta (PRD) as a study area, analyzes the spatial-temporal changes in air pollution (including sulfur dioxide (SO 2), nitrogen dioxide (NO 2), ozone (O 3), carbon monoxide (CO), and particles with an aerodynamic diameter less than 10 μm (PM 10) and less than 2.5 μm (PM 2.5)) from 2006 to 2019, and explores the relationship between air pollution and meteorological factors. The results showed that (1) most air pollutant concentrations decreased from 2006 to 2019, with the most obvious change being the decrease in the SO 2 concentration from 52.4 μg/m3 to 7.8 μg/m3. The O 3 concentration increased, with a Sen's slope of 0.649 μg m−3·year−1. Air pollution was lower in coastal areas (Shenzhen and Huizhou) than in inland areas (Foshan and Zhaoqing), affected by ocean atmospheric transmission, and coastal areas had the cleanest air quality. (2) Air pollutants had high correlations with air pressure, relative humidity, precipitation, and temperature. The most serious air pollution was found in winter, which was partially due to the meteorological conditions in winter that were more unfavorable for pollutant dispersion and dilution than were the conditions in other seasons. (3) Through the wavelet coherence method, an interesting finding revealed that other air pollution and meteorological factors exhibited complex period-dependent characteristics that were significantly related to PM 2.5. Areas with less air pollution were more susceptible to meteorological factors. (4) The overlapping area of the PM 2.5 distribution hotspot and nighttime light hotspot was mainly in Foshan and Guangzhou, representing approximately 12.1% of the study area. Our work contributes to the literature by considering seasonal and timescale-dependent characteristics of meteorological factors affecting air pollutant emissions, and it provides new insights into recognizing regions that need to prioritize urban air pollution control based on hotspot analysis. [Display omitted] • The mean SO 2 concentration decreased from 52.4 μg/m3 in 2006 to 7.8 μg/m3 in 2019. • The O 3 concentration increased with a Sen's slope of 0.649 μg m−3·year−1. • The time-frequency relationship between PM 2.5 and meteorological factors was explored by wavelet coherence. • Higher air pollution was detected in regions with higher night-time brightness. [ABSTRACT FROM AUTHOR]

• The built-up land of the Pearl River Delta was increased by 174 % from 1985 to 2015. • Built-up land is the main threat to regional ecological security. • Combining habitat quality and landscape ecological risk to identify zonal of ecological security. • Early warning zones and suggestions for future urban growth were provided. The Pearl River Delta (PRD) has experienced rapid urbanization processes for nearly 40 years. Due to the high population densities and developed industries, the region will continue to expand. To explore the impact of future land-use change on land ecological security, a regional ecological security early warning (ESEW) was spatially constructed by overlaying the simulated future built-up land with the current ecological security partition zones. The results showed that (1) the habitat quality was severely degraded in Pearl River Delta and the spatial differentiation was obvious, showing low habitat quality in the middle and high quality in the east and west; (2) the landscape ecological risk showed an increasing trend and the area of higher risk increased from 0.8 % to 7.4 % of the total area of the Pearl River Delta from 1985 to 2015; (3) each ecological security partition zone changed in different directions, and zone V changed from a single core to a multicore; (4) in the scenario of coordinated development under a balanced environment and economy, an equilibrium of each early warning level of ecological security will be reached. These results provide a reference for land-use planning, urban master planning and management decisions. [ABSTRACT FROM AUTHOR]

There is a significant challenge in resource management: the perceived trade-off between economic growth and ecosystem conservation. In this study, we integrate a variety of quantitative research methods and models, such as the ecosystem service value (ESV), interval parameter planning (IPP), Dyna-CLUE, and Monte Carlo methods, in an attempt to balance the ESV and economic benefits. The highest system benefits can be obtained, and uncertainty in the ecosystem assessment is considered. Taking the Pearl River Delta as the study area, the results show that when the GDP growth rate is less than 6%, the ESV in 2025 will be higher than the ESV in 2017. An interval approach (upper and lower bounds) is used. For a scenario with a 5% GDP growth rate, the ESV is RMB¥ [1.85, 20.79] × 109, which is more than the ESV of the scenario with a 9% GDP growth rate. When the GDP growth rates are 5% and 9%, the proportions of forestland are [61.5%, 61.7%] and [58%, 58.2%], respectively. Furthermore, spatialization was performed using the Dyna-CLUE model. In 2025, the simulated area of farmland is larger in some small regions with 9% GDP growth rate than it is in regions with 5% GDP growth rate, thus achieving a balance between occupation and compensation of regional farmland. By comparing ecosystem planning under different GDP growth rates, an optimized land-use allocation method can help decision makers balance system benefits and ecological risks, which can provide multiple options and specific locations for decision. Image 1 • A model was built to balance ecosystem services (ES) and economic benefits. • An evaluation system was built to assess the ESV in the lower and upper bounds. • Spatial differences in both ESV and land-use efficiency are considered. • An interval parameter planning (IPP) method and Dyna-CLUE model are integrated. • Decision makers are supported to balance system benefits and ecological risks. [ABSTRACT FROM AUTHOR]