Low Level Of Urbanization Research Articles

The heat-mortality association in Jordan: Effect modification by greenness, population density and urbanization level

BackgroundThe Middle East is one of the most vulnerable regions to the impacts of climate change, yet evidence of the heat-related mortality remains limited in this area. Our present study investigated the heat-mortality association in Jordan and the potential modifying effect of greenness, population density and urbanization level on the association. MethodsFor each of the 42 included districts, daily meteorological and mortality data from 2000 to 2020 were obtained for the warmest months (May to September). First, a distributed lag non-linear model was applied to estimate the district level heat-mortality association, then the district specific estimates were pooled using multivariate meta-regression models to obtain an overall estimate. Last, the modifying effect of district level greenness, population density and urbanization level was examined through subgroup analysis. ResultsWhen compared to the minimum mortality temperature (MMT, percentile 0th, 22.20 °C), the 99th temperature percentile exhibited a relative risk (RR) of 1.34 (95 % CI 1.23, 1.45). Districts with low greenness had a higher heat-mortality risk (RR 1.39, 95 % CI 1.22, 1.58) when compared to the high greenness (RR 1.28, 95 % CI 1.13, 1.45). While heat-mortality risk did not significantly differ between population density subgroups, highly urbanized districts had a greater heat-mortality risk (RR 1.41, 95 % CI 1.23, 1.62) as compared to ones with low levels of urbanization (RR 1.32, 95 % CI 1.13, 1.55). Districts with high urbanization level had the highest heat-mortality risk if they were further categorized as having low greenness (RR 1.63, 95 % CI 1.30, 2.04). ConclusionExposure to heat was associated with increased mortality risk in Jordan. This risk was higher in districts with low greenness and high urbanization level. As climate change-related heat mortality will be on the rise, early warning systems in highly vulnerable communities in Jordan are required and greening initiatives should be pursued.

Spatiotemporal Coupling Analysis of Urbanization and Ecosystem Services in Southeastern Fujian

Revealing the spatiotemporal coupling relationship between urbanization and ecosystem services can help to clarify regional development differences, optimize the implementation path of urbanization, and improve the quality of ecosystem services. Taking southeastern Fujian, a region with a good ecological foundation and strong urbanization potential, as a case study, the levels of multidimensional urbanization systems and typical ecosystem services of this region in the years 2000, 2010, and 2020 were quantified using the index comprehensive evaluation method and the InVEST model. The Pearson correlation coefficient and the coupling coordination degree model were used to analyze the spatiotemporal coupling relationship between urbanization and ecosystem services, and suggestions for improving regional coordinated development were proposed. The results showed that： ① The comprehensive urbanization level in southeastern Fujian increased continuously, with an average annual growth rate of 7.3%, of which social urbanization was the fastest, followed by economic urbanization and population urbanization, and spatial urbanization was relatively backward. Ecosystem services tended to decline, especially food and water provision services, which decreased by 61.9% and 46.9%, respectively. The spatial distribution showed a mismatch pattern of "high urbanization level and weak ecosystem services" in the southeast coastal area and "low urbanization level and strong ecosystem services" in the northwest inland area. ② The correlation between urbanization and ecosystem services was mainly negative. The negative effect of economic and social urbanization on ecosystem services was weaker than that of population and spatial urbanization, with a clear weakening tendency. As population and spatial urbanization slowed down sharply and economic and social urbanization accelerated, the driving force of urbanization development gradually shifted from "quantitative increase" to "qualitative improvement." Thus, the decline of ecosystem services was alleviated. ③ Comprehensive urbanization and various ecosystem services experienced three stages of "imbalance-transition-reconciliation," with an average increase of 60.5% to 120.6% in the coupling coordination degree. However, highly coordinated regions remained scarce, indicating that there is still significant room for improvement. The relative relationship between urbanization and ecosystem services evolved from urbanization lag to ecosystem services lag. The fluctuation problem of backward coupling coordination level caused by excessive urbanization had initially appeared in the southeastern coastal area. Therefore, in future construction, southeastern Fujian should improve economic quality and social benefits； strengthen the overall management, protection, and restoration of ecological space； and enhance the order and stability of the coordinated development of urbanization and ecosystem services.

Multilevel Change of Urban Green Space and Spatiotemporal Heterogeneity Analysis of Driving Factors

Analyzing the change trend of urban green space (UGS) and exploring related driving forces can provide scientific reference for sustainable development in rapidly urbanizing areas. However, the spatial and temporal driving mechanisms of the drivers on UGS patterns at different scales are still not deeply understood. Based on the GlobeLand30 land cover data, nighttime lighting data and spatial statistics from 2000 to 2020, this study analyzed the size, shape and diversity of UGS in Guangzhou at the urban level, gradient level and township level with multiple landscape indices. Diversity means the richness of UGS patch types. The selected indices include percent of landscape (PLAND), largest path index (LPI), landscape shape index (LSI), aggregation index (AI) and Shannon’s diversity index (SHDI). The spatiotemporal heterogeneity of the drivers was then explored using the spatiotemporal weighted regression (GTWR) method. Results showed the following: (1) During 2000−2020, the total amount of UGS in Guangzhou increased slightly and then decreased gradually. UGS was mainly transferred into artificial surfaces (lands modified by human activities). (2) The UGS landscape showed a non-linear trend along the urban–rural gradient and fluctuated more in the interval of 20–60% urbanization level. PLAND, LPI and AI decreased significantly in areas with higher levels of urbanization. LSI increased and SHDI decreased significantly in areas with lower levels of urbanization. At township level, the landscape indices showed significant spatial autocorrelation. They transformed from discrete changes at the edge and at the junction of the administrative district to large-scale aggregated change, especially in northern areas. (3) The size of UGSs was mainly influenced by natural factors and population density, but their shape and diversity were mainly influenced by socio-economic factors. More regular shapes of green patches were expected in higher urbanization areas. Population agglomeration positively influenced green space patterns in the northeastern and southern regions (Zengcheng, Conghua and Nansha). Meanwhile the negative influence of urban expansion on the green space pattern in the central and southern regions decreased over time. This study contributes to an in-depth understanding of how the key factors affect the different changes of UGS with time and space and provides methodological support for the long-term zoning planning and management of UGS.

Relative improvements between roads and railways and economic performance: A panel data analysis

Prior studies indicate that expanding the length of roadways and railways has a beneficial effect on economic performance. Nevertheless, the requirement for land transport infrastructure, which offers different degrees of accessibility and mobility, to facilitate economic expansion differs based on a country's stage of development. The present study has two objectives. Firstly, it is essential to ascertain the required investment for different types of land transport infrastructure to facilitate different stages of economic performance. Secondly, the objective is to examine the impact of different forms of land transportation infrastructure on economic performance by means of urbanization and exports. To highlight these concerns, a fixed-effects panel linear regression analysis was conducted on a panel consisting of 50 countries spanning the years 1980–2018. In countries with lower levels of urbanization and exports, improvements to road infrastructure, especially roads with high accessibility, are of greater importance for economic performance compared to the improvement of railways. Nevertheless, as urbanization and exports rise, the comparative impact of improvements in road infrastructure on economic performance in relation to improvements in railway infrastructure diminishes. Railway improvements have a more significant effect on economic performance compared to road improvements, owing to increased urbanization and export rates. During these stages of development, high-mobility roads are more crucial for economic performance compared to high-accessibility roads. The conclusion of the research examined a variety of policy recommendations derived from our findings, which are applicable to different levels of urbanization and exports.

High-resolution satellite images reveal the prevalent positive indirect impact of urbanization on urban tree canopy coverage in South America

Trees in urban areas act as carbon sinks and provide ecosystem services for residents. However, the impact of urbanization on tree coverage in South America remains poorly understood. Here, we make use of very high resolution satellite imagery to derive urban tree coverage for 882 cities in South America and developed a tree coverage impacted (TCI) coefficient to quantify the direct and indirect impacts of urbanization on urban tree canopy (UTC) coverage. The direct effect refers to the change in tree cover due to the rise in urban intensity compared to scenarios with extremely low levels of urbanization, while the indirect impact refers to the change in tree coverage resulting from human management practices and alterations in urban environments. Our study revealed the negative direct impacts and prevalent positive indirect impacts of urbanization on UTC coverage. In South America, 841 cities exhibit positive indirect impacts, while only 41 cities show negative indirect impacts. The prevalent positive indirect effects can offset approximately 48% of the direct loss of tree coverage due to increased urban intensity, with full offsets achieved in Argentinian and arid regions of South America. In addition, human activity factors play the most important role in determining the indirect effects of urbanization on UTC coverage, followed by climatic and geographic factors. These findings will help us understand the impact of urbanization on UTC coverage along the urban intensity gradient and formulate policies and strategies to promote sustainable urban development in South America.

Quantifying the impact of urbanization on wet deposition over Xiong'an New Area in northern China

AbstractXiong'an New Area (XNA) in China is undergoing rapid urbanization due to economic development and population growth. However, the urbanization process can significantly impact the local environment. This study applied a combined method of Weather Research and Forecasting (WRF) and empirical calculations to quantitatively identify changes in precipitation and wet deposition over XNA and its internal lake, Baiyangdian (BYD), during the summer months of June to September. Five different urbanization scenarios were established by varying the WRF subsurface conditions. By comparing these scenarios with historical observations, it was found that WRF simulations could effectively reproduce the precipitation and temperature changes in the region. This study examined how different levels of urbanization affect precipitation and estimated changes in PM2.5 wet deposition. The study's results indicate that as urbanization increases, it leads to an increase in precipitation and wet deposition in the XNA region. Using the relatively low urbanization level in 1980 as a benchmark for comparison, it was observed that when XNA becomes fully urbanized, the increase in precipitation and wet deposition in the region exceeds 7%. The BYD Lake can have a moderating effect on the environment, absorbing more than 50% of the local precipitation and PM2.5 wet deposition with less than 25% of its area, compared to the XNA interval of the statistics, while the increase in wet deposition in the BYD Lake area is more than 4% after full urbanization in XNA. The findings also emphasize the importance of the need to balance economic growth and environmental protection in urban planning and development.

Extra‐pair paternity enhances the reproductive fitness of urban Chinese blackbird

Urbanization is a human‐induced process of rapid habitat change that can affect the reproductive success of animals. The occurrence of extra‐pair paternity (EPP) may be sensitive to changes in urban ecological conditions. In this study, the Chinese blackbird Turdus mandarinus, a common breeding bird in southern Chinese cities, was selected as the focus species to explore the EPP patterns of monogamous birds in developing cities and the relationship between pairs. Over four breeding seasons, 316 Chinese blackbird nestlings and 20 adults in both urban and rural areas were monitored and genotyped for 11 microsatellite loci to determine progeny affinity. We confirmed that both the brood size and hatching rate of EPP nests were significantly larger than those of within‐pair paternity (WPP) nests. The body mass, beak length, head length, and body length of 12‐day age extra‐pair offspring (EPO) were significantly greater than those of within‐pair offspring (WPO), suggesting important benefits of EPP. However, in accordance with the analyses of nest ecological variables, we concluded that EPP occurs most often in areas with low urbanization levels, indicating some constraints for this reproductive strategy in cities. Our findings provide new insights about how this growing human‐induced landscape change affects mating behaviour in birds, an important aspect in avian ecology and evolution.

Factors Associated With Influenza Vaccination During Pregnancy: A Real-World Evidence-Based Study.

Pregnant women are at increased risk of influenza-related complications. However, the rate of influenza vaccination among pregnant women in Taiwan is low. By analyzing real-world data in this study, we investigated the factors associated with influenza vaccination during pregnancy in Taiwan. This study was a cross-sectional study. We collected real-world data from 2 databases in Taiwan: the Birth Certificate Database and the National Health Insurance Research Database. The study population was pregnant between October 2014 and December 2016 in Taiwan. The multivariate logistic regression was performed to identify factors associated with influenza vaccination, including maternal sociodemographics, trimester, comorbidities, and health-care utilization. The vaccination rate of among pregnant women was 8.2%. Factors significantly associated with a high likelihood of influenza vaccination were age between 30 and 34 years (odds ratio [OR]: 1.14; 95% confidence interval [CI]: 1.10-1.19), second trimester (OR: 1.80; 95% CI: 1.75-1.85), income equal to or exceeding NT$ 38 201 (OR: 1.92; 95% CI: 1.86-1.99), hypertension (OR: 1.16; 95% CI: 1.05-1.29), cardiovascular disease (OR: 1.29; 95% CI: 1.17-1.42), autoimmune disease (OR: 1.47; 95% CI: 1.38-1.58), and chronic pulmonary disease (OR: 1.24; 95% CI: 1.18-1.31). A low level of urbanization, at least 1 hospitalization in the previous year, and the presence of pregnancy complications (eg, gestational diabetes, preeclampsia, and placenta previa) were associated with a lower likelihood rate of influenza vaccination. The influenza vaccination rate among pregnant women in Taiwan was low. Age, gestational age, income level, urbanization level, hypertension, cardiovascular disease, autoimmune disease, chronic pulmonary disease, and pregnancy complications may be associated with influenza vaccination among pregnant women.

Defining nutrient ecoregions for reference nitrogen and phosphorus concentrations in rivers from the major South American biomes

Delineating reference (i.e., baseline) riverine nutrient concentrations is essential to understand fundamental processes of biogeochemical transport from continents to the ocean, describe ecological conditions, and inform managers of best attainable conditions when attempting to control anthropogenic eutrophication. We used data from 434 Brazilian watersheds representative of major South American biomes covering over half the continental area, to estimate nutrient levels expected prior to anthropogenic development. We used a novel watershed-based approach to describe spatial patterns throughout Brazil and for the entire Amazon basin. This approach considered nitrogen (N) and phosphorus (P) independently and allowed removal of anthropogenic influences. The approach was useful where there were few unimpacted watersheds and low levels of urbanization had strong effects. We found reference total N concentrations were most closely related to biome, whereas total P levels related to percentage sand in soils in addition to climatic features influencing biomes. There was a wide range of N:P at this coarse level, suggesting P or co-limitation could occur in streams; many areas have intrinsically high background P and relatively low N, suggesting N-limitation of freshwaters could be widespread in South America, favoring nitrogen-fixing cyanobacterial blooms. We provide unique broad-scale analyses of spatial distribution of baseline nutrient levels for tropical and subtropical watersheds across continental scales.

A quantitative framework to evaluate urban ecological resilience: broadening understanding through multi-attribute perspectives

Intensive human and economic activities in urban areas have had adverse effects on local resources and ecology, leading to a decline in ecological resilience. Enhancing ecological resilience is crucial for improving the urban ecosystem's ability to withstand and recover from external risks. However, quantitative research on urban ecological resilience remains somewhat ambiguous, with many studies lacking comprehensive assessment methods from multiple perspectives. In this study, we established a comprehensive framework to assess urban ecological resilience based on four regime attributes. The study's results indicated the following key findings: The average urban ecological resilience value exhibited a trend of initially declining and then recovering. Cities proposed different approaches when considering and managing social and ecological relationships during the development process. A significant correlation between urbanization levels and ecological resilience was observed, with urban ecological resilience increasing in areas with low urbanization levels and sharply decreasing in areas with high urbanization levels. The findings from this study provide a specific theoretical foundation for decision-makers involved in urban planning and development strategies.

Research on the Impact of the Digital Economy on Carbon Pollution Based on the National Big Data Comprehensive Pilot Zone in China

The digital economy (DE) is increasingly recognized as a principal driver of high-quality economic development. With the dual carbon goals of carbon peak and carbon neutrality, it is essential to urgently discuss whether the DE can also provide an aid to restrain carbon pollution. For this reason, the purpose of this paper is to examine the influence of the DE on urban carbon pollution and its underlying mechanism, utilizing balance panel data for Chinese cities from 2012 to 2021. Additionally, this study adopts the quasi-natural experiment in the National Big Data Comprehensive Pilot Zone to empirically analyze this relationship using the Difference-in-Differences (DID) and mediating effect models. The findings indicate that the DE can significantly decrease carbon pollution, exhibiting a clear carbon pollution reduction effect. These conclusions remain valid even after implementing various robustness tests. This examination of the action mechanism reveals that it is effective for the DE to mitigate urban carbon pollution by enhancing energy efficiency and attracting foreign investment. Further analysis of heterogeneity reveals that it is more effective for the DE to reduce carbon pollution in the non-resource-based cities, large cities, eastern regions, and cities with high urbanization levels as compared to the resource-based cities, small or mega cities, central and western regions, and cities with a low level of urbanization. These findings not only offer robust objective evidence for the positive influence of the DE on carbon pollution reduction, but also present valuable policy implications for minimizing carbon pollution and enhancing environmental quality.

The impact of agricultural productive service on agricultural carbon efficiency—From urbanization development heterogeneity

Agricultural productive service plays an important role in China's modernization of agricultural production, and its development is closely related to urbanization. However, its effect on agricultural carbon efficiency has seldom been discussed at different stages of urbanization level. Thus, the paper investigated the relationship between agricultural productive service and agricultural carbon efficiency considering the change in urbanization level, using panel data of China's 31 provinces from 2010 to 2020. We find that agricultural productive service can promote agricultural carbon efficiency, and its promotion effect of agricultural productive service will become more powerful with the increase of urbanization level. In addition, its promotion effect is relatively powerful in China's eastern provinces, while relatively weak in central and western provinces characterized by low urbanization levels. According to the paper's findings, we propose that we should strengthen the development of agricultural productive service in breadbasket provinces and focus on the coordinated development between agricultural productive service and urbanization.

Association Between Retirement Age and Incidence of Depressive Disorders: A 19-Year Population-Based Study

To investigate the occurrence of depressive disorders spanning the transition to retirement, and explore the relationship between retirement age and depressive disorders. We utilized a national population-based health insurance database encompassing 2 million Taiwanese individuals from 2000 to 2019. The study focused on individuals aged 50 years and older who were employed at the baseline, and 84,224 individuals had records of retirement during the follow-up period. Depressive disorders were identified using codes from the International Classification of Diseases. To assess the trend in the incidence of depressive disorders 7-year period before and after retirement, an interrupted time series analysis was performed. Cox-proportional hazard models were employed to investigate the association between retirement age and the occurrence of depressive disorders following retirement. The incidence of depression peaks at the time of retirement and shows a significant decrease after retirement. Incidence of depressive disorders was 6.4 and 7.6 per 1000 person-years among individuals who retired between the ages of 60-64 and 65-69. Comparing the two groups, those who retired between 65 and 69 exhibits a higher risk of developing depressive disorders (hazard ratio=1.10, 95% confidence interval=1.02-1.18). This association is particularly pronounced among women and individuals residing in areas with low urbanization levels. Retirement marks a crucial life milestone accompanied by a peak in depressive disorders. It is important to address the higher risk of depression associated with late retirement among socially disadvantaged groups.

Spatial influence of exposure to green spaces on the climate comfort of urban habitats in China

This study aimed to improve the number of days with comfortable climate by increasing urban green space exposure. Geographic information technology and a spatial econometrics model were used to analyze the spatial influence and heterogeneity of urban green spaces on the climate comfort of urban habitats in China. The model was built using urban green space data extracted from remote sensing images, and days with comfortable climatic conditions, measured through the temperature and humidity index. The results showed that exposure to green space was generally high in Northeast and Southwest China, and low in Northwest and Southeast China. The exposure to green space of high urbanization level cities is generally lower than cities with low urbanization level. The climate comfort of urban habitats in the northeast and northwest is relatively cold, whereas that of those in the south, central and east is relatively hot. Southwest China has a complex and diverse range of climates. The climate of North China experiences greatly extremes of cold and heat in a year. The significance and mechanism of the influence of exposure to urban green space on climate comfort are differences in different regions. High exposure to green space can adjust thermal comfort by means of water storage, transpiration and heat absorption, reducing the range of temperature difference between day and night, and blocking cold and warm air flow. In addition, moderate human activities and sustainable land use can improve exposure to green space to help vegetation fully contact the air, affecting climate comfort by promoting evaporation and reducing thermal radiation.

Non-linear effects of multi-dimensional urbanization on ecosystem services in mega-urban agglomerations and its threshold identification

The rapid urbanization process of urban agglomerations had complex and non-linear effects on various ecosystem services (ESs), particularly within mega-urban agglomerations. Previous studies have focused on the non-linear impacts of urbanization on comprehensive ESs within single urban agglomerations. However, research on the non-linear relationship between multi-dimensional urbanization and different ES types across entire mega-urban agglomerations and the identification of impact thresholds remains limited. This lack of investigation has considerably hampered the formulation of targeted policies for urbanization development and ecological management. Addressing these research gaps, this study takes a holistic approach by taking the BTH-UA, PRD-UA, and YRD-UA as a whole and employs a threshold regression model to measure the non-linear impacts of multi-dimensional urbanization on different ES types, along with identifying critical thresholds. The results are as follows: In terms of temporal evolution, urbanization has progressed most rapidly in the YRD-UA and PRD-UA, contributing to varying degrees of ES decline. In contrast, despite the relatively low urbanization level in the BTH-UA, ESs are on the rise. Spatially, mega-urban agglomerations exhibited a “core-periphery” pattern in both urbanization and ESs distribution. High urbanization levels were found clustered in core regions, while elevated ESs levels were prevalent in the peripheries, indicating significant spatial disparities. The effects of both population urbanization (PU) and land urbanization (LU) on carbon storage (CS) exhibited an inverted U-shaped curve with thresholds of 272 people/km2 and 1.063%, respectively. The effect of LU on food production (FP) had a U-shaped curve with a threshold of 0.704%. The findings indicate that the impacts of PU and LU on ESs exhibit more complex characteristics in urbanization systems. The results of the study underscore the significance of regulating population density and urban expansion intensity to improve ESs within mega-urban agglomerations. This research offers valuable support for policy formulation and sustainable development planning in these large urban clusters.

Direct and indirect effects of urbanization, pesticides and wild insect pollinators on mango yield

Abstract Expanding cities increasingly encroach fertile farmlands, questioning the viability of maintaining agriculture within and around them. Yet, our knowledge on how urbanization influences pollinator communities and the provision of pollination services to crops is limited, especially for the urbanization hotspots of the Global South. Mango Mangifera indica is one of the most important fruit crops in tropical countries. To analyse the dependency of mango on its main insect pollinators, and the direct and indirect effects of urbanization and insecticides on pollinator abundance and mango yield, we conducted a pollinator exclusion experiment and sampled flower visitors on 16 mango farms spread across rural–urban landscapes in Bengaluru, a South Indian megacity. We found that allowing flowers access to ants and flying visitors (bees, hoverflies, nonsyrphid flies), dramatically increased mango yield by 350%, highlighting the importance of wild insects for mango pollination. We detected a trend between wild bee abundance and the final fruit set, with an increase of 20% when the number of bees increased from 25 to 125. Urbanization did not directly affect pollinator abundance or mango yield. However, the amount of insecticide applications had strong negative effects on wild bee abundance at low and intermediate levels of urbanization, while it had no effect in highly urbanized areas, presumably because of higher availability of flowering resources. Moreover, the amount of insecticides decreased the weight of harvested mango fruits by almost 30%. This may indicate trade‐offs between conventional pest control and enhanced crop yields through pollination by wild insects in rural areas. Synthesis and applications: Our results indicate that mango production can be maintained at a profitable level in urbanized landscapes with insect pollinators more than tripling final yield. However, increasing use of insecticides, besides raising farmers' expenses, can have negative effects on wild insect pollinators and mango yield, especially in rural areas. To safeguard crucial pollination services, it is therefore critical to conserve and promote wild insect pollinators by minimizing the negative effects of insecticide applications in these areas.

Ecological Health Assessment of an Urban River: The Case Study of Zhengzhou City, China

Urban river ecological health assessment is an effective means to manage urban rivers, and combining principles of landscape ecology can provide new help for the ecological restoration of urban rivers and improving their ecosystem service value. From the perspective of important functions of ecosystems, based on typical sample site investigations of different river sections, questionnaire surveys, and remote sensing technology, a fuzzy comprehensive evaluation model based on the factor analysis method was used to construct an indicator system that can quantitatively reflect the ecological health of urban rivers. This comprehensive evaluation index system includes five major functions: social function, habitat and corridor function, water ecological function, water landscape function, and spatial enclosure function. The study identified key areas, key rivers, key river sections, and main indicator projects for the ecological restoration of the urban river landscape corridors in Zhengzhou. The study results also showed that the urban river landscape corridors in Zhengzhou have prominent problems in social function, water ecological function, and habitat and corridor function, and 62.1% of the river sections are currently in a sub-healthy state. The flood control function, eutrophication of water body, naturalization rate of revetment, and five other indicators in the old city district are significantly lower than those in the new city district, and the old city district should be the focus of the ecological restoration of urban river corridors. From the evaluation of the ecological health status of typical river sections, the Jinshui River and Xionger River have a larger number of river sections that urgently need restoration. This study provides a reference for the ecological restoration of urban rivers in Zhengzhou, a rapidly urbanizing region, and has reference significance for the construction of water landscapes in small and medium-sized cities with low levels of urbanization.

Urbanization influenced the interactions between dissolved organic matter and bacterial communities in rivers

Increased urbanization and anthropogenic activities can alter dissolved organic matter (DOM) and complicate its interaction with bacteria in rivers' ecosystems, however, there is limited information about how bacterial communities respond to DOM components in rivers with different urbanization levels. Here, we combined spectroscopy-based DOM analysis and 16S rRNA gene amplicon sequencing to investigate the associations of bacterial taxa and DOM properties as well as the impacts of DOM on bacterial niche breadth in North River (NR) and West River (WR) of Jiulong River watershed, southern China, which had low and high urbanization levels, respectively. Spectroscopy analysis showed that hydrophilic DOM was predominant in both rivers whereas chromophoric DOM was higher in WR. Network analysis indicated that only seven bacterial genera (i.e., hg clade, chthoniobacter, Geobacter, Acidibacter, Alphal Cluster, Fluviicola, and Lacunisphaera) showed strong associations with DOM optical variables in both rivers, whereas more than 85% of DOM-bacterial genera associations were different between rivers. These results suggest that the relationship between DOM and bacterial communities had different responses in rivers with different urbanization levels. The partial least square path model indicated that the total standardized effect of physico-chemicals on bacterial niche breadth was higher in NR (0.62) than in WR (0.35), whereas humic substances showed an opposite pattern (NR: −0.42; WR: 1.67). The distinct effects of physico-chemicals and DOM on bacterial niche breadths between rivers could be due to the different effects of urbanization and human activities on the environmental conditions of riverine ecosystems. Our findings revealed a huge dissimilarity in the bacteria-DOM co-occurrence networks between rivers with different urbanization levels and provide a novel insight that urbanization may enhance DOM's importance to bacterial niche breadths.

Rapid urbanization affects microplastic communities in lake sediments: A case study of Lake Aha in southwest China

Effective management of pollutants in urban environments is crucial for achieving sustainable cities. Microplastics, as an emerging pollutant widely present in contemporary environments, have received widespread attention in recent years. However, limited studies have reported the impact of rapid urbanization on regional microplastics. In this study, the abundance and composition of microplastic communities in the sediments of Lake Aha were analyzed using a “microplastic community” and slicing the sediments at 5 cm intervals. Results showed that microplastic abundance of sediments in Lake Aha was relatively high (up to 1700 items/kg) and decreased with increasing depth, with the highest abundance found in the surface layer (0–5 cm, 1090 ± 474 items/kg). Hierarchical cluster analysis (HCA), principal component analysis (PCA), and analysis of similarities (ANOSIM) revealed that the different sediment layers could be classified into high and low urbanization level groups based on the composition of microplastic communities. Linear discriminant analysis effect size (LEfSe) indicated that agricultural input was the main source of microplastic pollution during low urbanization levels, characterized by low abundance, large particle size, and high fiber proportion, while urban activities dominated during high urbanization levels, with high abundance, small particle size, high proportion of Polyethylene terephthalate (PET), fragments, and granules, and colorful microplastics. This study clarifies the impact of urbanization on the abundance and composition of microplastics in lake sediments, which has implications for more effective management and control of microplastic pollution in regions undergoing rapid urbanization.

Environmental, geographical and time‐related impacts on avian malaria infections in native and introduced populations of house sparrows (Passer domesticus), a globally invasive species

AbstractAimThe increasing spread of vector‐borne diseases has resulted in severe health concerns for humans, domestic animals and wildlife, with changes in land use and the introduction of invasive species being among the main possible causes for this increase. We explored several ecological drivers potentially affecting the local prevalence and richness of avian malaria parasite lineages in native and introduced house sparrows (Passer domesticus) populations.LocationGlobal.Time period2002–2019.Major taxa studiedAvian Plasmodium parasites in house sparrows.MethodsWe analysed data from 2,220 samples from 69 localities across all continents, except Antarctica. The influence of environment (urbanization index and human density), geography (altitude, latitude, hemisphere) and time (bird breeding season and years since introduction) were analysed using generalized additive mixed models (GAMMs) and random forests.ResultsOverall, 670 sparrows (30.2%) were infected with 22 Plasmodium lineages. In native populations, parasite prevalence was positively related to urbanization index, with the highest prevalence values in areas with intermediate urbanization levels. Likewise, in introduced populations, prevalence was positively associated with urbanization index; however, higher infection occurred in areas with either extreme high or low levels of urbanization. In introduced populations, the number of parasite lineages increased with altitude and with the years elapsed since the establishment of sparrows in a new locality. Here, after a decline in the number of parasite lineages in the first 30 years, an increase from 40 years onwards was detected.Main conclusionsUrbanization was related to parasite prevalence in both native and introduced bird populations. In invaded areas, altitude and time since bird introduction were related to the number of Plasmodium lineages found to be infecting sparrows.