Exposure of water purification deficit network in response to nitrogen application intensity.

Ecosystem services are strongly responsive to changes in land use intensity, especially water purification, which is highly sensitive to water pollutant emission. Increased nitrogen (N) application to cropland has potential impacts on the supply and demand for water purification through changes in land use intensity. However, there has been a lack of research focusing on the impacts of cropland N application on population exposure to water purification deficits and their cross-regional delivery network. Taking the Dongting Lake (DTL) Basin as an example, this study explored the spatial pattern of N exposure in the DTL Basin from 1990 to 2015 by integrating water purification deficit and population density. Changes in potential N exposure in 2050 were simulated based on population projection data from the Shared Socioeconomic Pathways (SSP1-5). N export pathways in the DTL Basin were clarified by constructing the N delivery network. The results showed that (1) N exposure increased significantly with increasing N application in DTL Basin. (2) The DTL surrounding area and lower reaches of the Xiangjiang River Basin had high increases of N exposure (50.2 % and 71.6 %) and high increases in N exposure due to increases in N application per unit (N influence coefficients exceeding 0.5). (3) The lower reaches of the Xiangjiang River Basin with the highest population density had the smallest decrease in N exposure (1.4 %-11.1 %) in the SSP1-5 scenarios. (4) During 1990-2015, the increase of N export to the DTL surrounding area was higher in the lower reaches sub-basins of DTL Basin. N application had a stronger impact on N delivery processes in the lower reaches of DTL Basin. Managers should distribute N applications to basins with high N retention and whose N export to the DTL surrounding area is weak. This study confirmed the strong response of water purification deficits and their population exposures to N application, and provided decision-making guidelines for water quality enhancement programs in DTL Basin from a spatial planning perspective.

Age and Density of Mated Females Affect Dispersal Strategies in Spider Mite Tetranychus ludeni Zacher.

The dispersal strategies of a species can affect its invasion success. Investigations into the dispersal strategies of invasive species in relation to different factors help improve our understanding of invasion mechanisms and provide knowledge for population management and invasion evaluation. Tetranychus ludeni Zacher (Acari: Tetranychidae) is an invasive species which is native to Europe but is now cosmopolitan. Here, we examined the effects of age and density on dispersal in mated females. Our results show that older females that are capable of producing more eggs within 24 h were more likely to disperse and moved longer distances than younger ones with fewer eggs. Older females spread most of their eggs out of their natal habitats and over longer distances, which reduced competition and increased offspring fitness. Females exhibited significantly increased dispersal probability and distances with an increase in population density to avoid crowding. The synchronization of dispersal and reproduction, along with the positive density-dependent dispersal strategy, may facilitate the habitat colonization and invasion speed of T. ludeni.

Population Density and Health Outcomes in Women with HIV in the Southern United States: A Retrospective Longitudinal Analysis.

Purpose: Published studies have revealed challenges for people with human immunodeficiency virus (HIV) living in rural areas compared to those in urban areas, such as poor access to HIV care, insufficient transportation, and isolation. The purpose of this study was to examine associations between population density and multiple psychosocial and clinical outcomes in the largest cohort of women with HIV (WWH) in the United States. Methods: Women's Interagency HIV Study (WIHS) participants from Southern sites (n = 561) in 2013-2018 were categorized and compared by population density quartiles. The most urban quartile was compared with the most rural quartile in several psychosocial and clinical variables, including HIV viral load suppression, HIV medication adherence, HIV care attendance, depression, internalized HIV stigma, and perceived discrimination in healthcare settings. Results: Although women in the lowest density quartile were unexpectedly more highly resourced, women in that quartile had greater odds of not attending an HIV care visit in the last six months (odds ratio [OR] = 0.64, 95% confidence interval [CI] [0.43-0.95]), yet higher odds for having fully suppressed HIV when compared to women in the highest density quartile (OR = 1.64, 95% CI [1.13-2.38]). Highly urban WWH had greater likelihood of unsuppressed HIV, even after controlling for income, employment, and health insurance, despite reporting greater HIV care adherence and similar medication adherence. Discussion: Further investigation into the reasons for these disparities by population density is needed, and particular clinical attention should be focused on individuals from high population density areas to help maximize their health outcomes.

When population growth intensifies intergroup competition, female colobus monkeys free-ride less.

Intergroup aggression often results in the production of public goods, such as a safe and stable social environment and a home range containing the resources required to survive and reproduce. We investigate temporal variation in intergroup aggression in a growing population of colobus monkeys (Colobus vellerosus) to ask a novel question: "Who stepped-up to produce these public goods when doing so became more difficult?". Both whole-group encounters and male incursions occurred more frequently as the population grew. Males and females were both more likely to participate in whole-group encounters when monopolizable food resources were available, indicating both sexes engaged in food defence. However, only females increasingly did so as the population grew, suggesting that it was females who increasingly produced the public good of home range defence as intergroup competition intensified. Females were also more active in male incursions at high population densities, suggesting they increasingly produced the public good of a safe and stable social environment. This is not to say that males were chronic free-riders when it came to maintaining public goods. Males consistently participated in the majority of intergroup interactions throughout the study period, indicating they may have lacked the capacity to invest more time and effort.

A Canine Distemper Outbreak in Urban Red Foxes (Vulpes vulpes) in Brussels, Belgium, 2020.

Canine distemper has been observed infrequently in Belgian wildlife, mainly stone martens (Martes foina) and red foxes (Vulpes vulpes). This report describes an outbreak in the Brussels urban red fox population, characterized by its high density. The identified virus matched those within a cluster of viruses found previously in red foxes in Germany. Different canine distemper virus (CDV) strains, found in Belgian wild carnivores, share relationships with viruses found farther east. This and other reports indicate an endemic distribution of CDV in wild carnivores in Europe whereby the complex interplay of population density, group immunity, and infection of metapopulations determines the pattern of spatiotemporally alternating outbreaks.

Spatial structure could explain the maintenance of alternative reproductive tactics in tree cricket males.

Trait polymorphisms are widespread in nature, and explaining their stable co-existence is a central problem in ecology and evolution. Alternative reproductive tactics, in which individuals of one or more sex exhibit discrete, discontinuous traits in response to reproductive competition, represent a special case of trait polymorphism in which the traits are often complex, behavioural, and dynamic. Thus, studying how alternative reproductive tactics are maintained may provide general insights into how complex trait polymorphisms are maintained in populations. We construct a spatially explicit individual-based model inspired from extensively collected empirical data to address the mechanisms behind the co-existence of three behavioural alternative reproductive tactics in males of a tree cricket (Oecanthus henryi). Our results show that the co-existence of these tactics over ecological time scales is facilitated by the spatial structure of the landscape they inhabit, which serves to equalise the otherwise unequal mating benefits of the three tactics. We also show that this co-existence is unlikely if spatial aspects of the system are not considered. Our findings highlight the importance of spatial dynamics in understanding ecological and evolutionary processes and underscore the power of integrative approaches that combine models with empirical data.

Experimental manipulation of food availability and macroparasite prevalence reveal differential effects on space use in wild rodents.

Research Highlight: Mistrick, J., Veitch, J. S. M., Kitchen, S. M., Clague, S., Newman, B. C., Hall, R. J., Budischak, S. A., Forbes, K. M., & Craft, M. E. (2024). Effects of food supplementation and helminth removal on space use and spatial overlap in wild rodent populations. Journal of Animal Ecology. http://doi.org/10.1111/1365-2656.14067. The spread of pathogens has been of long-standing interest, even before dramatic outbreaks of avian influenza and the coronavirus pandemic spiked broad public interest. However, the dynamics of pathogen spread in wild populations are complex, with multiple effects shaping where animals go (their space use), population density and, more fundamentally, the resultant patterns of contacts (direct or indirect) among individuals. Thus, experimental studies exploring the dynamics of contact under different sets of conditions are needed. In the current field study, Mistrick et al. (2024) used a multifactorial experimental design, manipulating food availability and individual pathogen infection state in wild bank voles (Clethrionomys glareolus). They found that while food availability, individual traits and seasonality can affect how far individual voles moved, the degree of overlap between individual voles remained largely the same despite a high variation in population density-which itself was affected by food availability. These results highlight how biotic and abiotic factors can shape patterns of space use and balance the level of spatial overlap through multiple pathways.

Combined biomass network design: A new integrated approach based on ArcGIS.

In light of contemporary energy and environmental objectives, a pivotal transformation of the energy system, encompassing biomass energy, is imperative. A notable challenge in biomass energy facility layout planning is the trade-off between high-efficiency production and the associated investment costs. To harmonize energy efficiency with economy viability, a hybrid layout with the simultaneous construction of centralized and decentralized biomass energy facilities has emerged as a crucial strategic solution. However, the delineation methods for these two layouts lack explicit data support. This study established a population density threshold (PDT) suitable for selecting the distributed layout and employed population density as the criterion for delineating the two layouts. Taking Fuxin City as an example, hybrid layout planning schemes were generated under different PDTs, and a cost and energy benefit analysis framework was developed for these schemes. The results indicated that the scheme with a PDT of 145 person/km2 exhibited the highest energy and economic comprehensive benefits. Compared to a single layout, the planning strategy proposed in this study could achieve nearly the same energy surplus level while saving an investment cost ranging from 2403.9 million CNY to 25,000.23 million CNY. The findings are applicable to other regions with similar conditions, and the analysis framework proposed in this study can be utilized in formulating biomass development strategies for other countries and regions.

Post-COVID-19: Time to Change Our Way of Life for a Better Future.

Background and Objectives: From the year 1 anno Domini until 1855, with the third plague, major pandemics occurred on average every 348 years. Since then, they have occurred on average every 33 years, with coronavirus disease 2019 (COVID-19) now underway. Even though current technologies have greatly improved the way of life of human beings, COVID-19, with more than 700,000,000 cases and 6,950,000 deaths worldwide by the end of 2023, reminds us that much remains to be done. This report looks back at 18 months of COVID-19, from March 2020 to August 2021, with the aim of highlighting potential solutions that could help mitigate the impact of future pandemics. Materials and Methods: COVID-19 data, including case and death reports, were extracted daily from the Worldometer platform to build a database for the macroscopic analysis of the spread of the virus around the world. Demographic data were integrated into the COVID-19 database for a better understanding of the spatial spread of the SARS-CoV-2 virus in cities/municipalities. Without loss of generality, only data from the top 30 (out of 200 and above) countries ranked by total number of COVID-19 cases were analyzed. Statistics (regression, t-test (p < 0.05), correlation, mean ± std, etc.) were carried out with Excel software (Microsoft® Excel® 2013 (15.0.5579.1001)). Spectral analysis, using Matlab software (license number: 227725), was also used to try to better understand the temporal spread of COVID-19. Results: This study showed that COVID-19 mainly affects G20 countries and that cities/municipalities with high population density are a powerful activator of the spread of the virus. In addition, spectral analysis highlighted that the very first months of the spread of COVID-19 were the most notable, with a strong expansion of the SARS-CoV-2 virus. On the other hand, the following six months showed a certain level of stability, mainly due to multiple preventive measures such as confinement, the closure of non-essential services, the wearing of masks, distancing of 2 m, etc. Conclusion: Given that densely populated cities and municipal areas have largely favored the spread of the SARS-CoV-2 virus, it is believed that such a demographic context is becoming a societal problem that developed countries must address in a manner that is adequate and urgent. COVID-19 has made us understand that it is time to act both preventatively and curatively. With phenomenological evidence suggesting that the next pandemic could occur in less than 50 years, it may be time to launch new societal projects aimed at relieving congestion in densely populated regions.

On an Aggregated Estimate for Human Mobility Regularities through Movement Trends and Population Density.

This article introduces an analytical framework that interprets individual measures of entropy-based mobility derived from mobile phone data. We explore and analyze two widely recognized entropy metrics: random entropy and uncorrelated Shannon entropy. These metrics are estimated through collective variables of human mobility, including movement trends and population density. By employing a collisional model, we establish statistical relationships between entropy measures and mobility variables. Furthermore, our research addresses three primary objectives: firstly, validating the model; secondly, exploring correlations between aggregated mobility and entropy measures in comparison to five economic indicators; and finally, demonstrating the utility of entropy measures. Specifically, we provide an effective population density estimate that offers a more realistic understanding of social interactions. This estimation takes into account both movement regularities and intensity, utilizing real-time data analysis conducted during the peak period of the COVID-19 pandemic.

Leopard density and determinants of space use in a farming landscape in South Africa.

Protected areas are traditionally the foundation of conservation strategy, but land not formally protected is of particular importance for the conservation of large carnivores because of their typically wide-ranging nature. In South Africa, leopard (Panthera pardus) population decreases are thought to be occurring in areas of human development and intense negative interactions, but research is biased towards protected areas, with quantitative information on population sizes and trends in non-protected areas severely lacking. Using Spatially Explicit Capture-Recapture and occupancy techniques including 10 environmental and anthropogenic covariates, we analysed camera trap data from commercial farmland in South Africa where negative human-wildlife interactions are reported to be high. Our findings demonstrate that leopards persist at a moderate density (2.21 /100 km2) and exhibit signs of avoidance from areas where lethal control measures are implemented. This suggests leopards have the potential to navigate mixed mosaic landscapes effectively, enhancing their chances of long-term survival and coexistence with humans. Mixed mosaics of agriculture that include crops, game and livestock farming should be encouraged and, providing lethal control is not ubiquitous in the landscape, chains of safer spaces should permit vital landscape connectivity. However, continuing to promote non-lethal mitigation techniques remains vital.

Invasive freshwater snails are less sensitive to population density than native conspecifics.

Understanding how and why some species or lineages become invasive is critically important for effectively predicting and mitigating biological invasions. Here, we address an important unanswered question in invasion biology: do key life-history traits of invasive versus native lineages within a species differ in response to key environmental stressors? We focus on the environmental factor of population density, which is a fundamental characteristic of all populations, and investigate how changes in density affect native versus invasive Potamopyrgus antipodarum (New Zealand mudsnail). P. antipodarum has invaded 39 countries and detrimentally affects invaded environments. Previous studies of native and invasive populations and from laboratory experiments have demonstrated that growth and reproduction of P. antipodarum is sensitive to population density, though whether and how this sensitivity varies across native versus invasive lineages remains uncharacterized. We quantified individual growth rate and reproduction in P. antipodarum from multiple distinct native and invasive lineages across three different population density treatments. The growth of native but not invasive lineages decreased as density increased. There was no differential effect of density treatment on embryo production of invasive versus native snails, but a significantly higher proportion of snails were reproductive in high density compared to intermediate density for invasive lineages. In native lineages, there were no significant differences in the relative frequency of reproductive snails across density treatments. While the extent to which these results from our laboratory study can be extrapolated to the more complex natural world remain unclear, our findings are consistent with a scenario where differential sensitivity to population density could help explain why some lineages become successful invaders. Our findings also align with previous studies that show that invasive P. antipodarum lineages exhibit a relatively wide range of tolerance to environmental stressors.

Urban densification in the Netherlands and its impact on mental health: An expert-based causal loop diagram.

Urban densification is a key strategy to accommodate rapid urban population growth, but emerging evidence suggests serious risks of urban densification for individuals' mental health. To better understand the complex pathways from urban densification to mental health, we integrated interdisciplinary expert knowledge in a causal loop diagram via group model building techniques. Six subsystems were identified: five subsystems describing mechanisms on how changes in the urban system caused by urban densification may impact mental health, and one showing how changes in mental health may alter urban densification. The new insights can help to develop resilient, healthier cities for all.

Understanding microplastic presence in different wastewater treatment processes: Removal efficiency and source identification.

Municipal effluents discharged from wastewater treatment plants (WWTPs) are a considerable source of microplastics in the environment. The dynamic profiles of microplastics in treatment units in WWTPs with different treatment processes remain unclear. This study quantitatively analyzed microplastics in wastewater samples collected from different treatment units in two tertiary treatment plants with distinct processes. The influents contained an average of 15.5 ± 3.5 particles/L and 38.5 ± 2.5 particles/L in the two WWTPs with in the oxidation ditch process and the integrated fixed-film activated sludge process, respectively. Interestingly, microplastic concentrations in the influent were more influenced by the population density in the served area than sewage volume or served population equivalent. Throughout the treatment process, concentrations were reduced to 1.5 ± 0.5 particles/L and 1.0 ± 1.0 particles/L in the final effluents, representing an overall decrease of 90% and 97%, in WWTPs with the oxidation ditch process and integrated fixed-film activated sludge process, respectively. A significant proportion of the microplastics were removed during the primary treatment stage in both WWTPs, with better performance for foam, film, line-shaped and large-sized microplastics. Most microplastics were accumulated in activated sludge, indicating its key role as the primary sink in WWTPs. The multiple correspondence analysis identified laundry washing and daily necessities such as packaging and containers as the major contributors to microplastics in WWTPs. The study proposed recommendations for upgrading WWTPs, modifying designs, and implementing strategies to reduce microplastic sources, aiming to minimize the release of microplastics into the environment. These findings can shed lights on the sources of microplastics in WWTPs, and advance our understanding of the mechanisms for more effective microplastic removals in wastewater treatment technologies in future applications.

Effects of group size on movement patterns and clustering dynamics in rats.

Environment is a determining factor that can facilitate or hinder social interactions. A precursor to meaningfully engaging with conspecifics is being exposed to opportunistic encounters with others. Increasing the number of individuals in a given space (thus increasing density) would, statistically speaking, increase the likelihood of accidental encounters. This might have consequences on the formation of social networks-an idea that has not reliably been explored. If true, we would expect that increasing density would lead to an increase in the number and the duration of 'clusters' of animals. Here, we examined whether varying the number of rats in an open field environment differentially affected their movement dynamics or their propensity to aggregate into clusters and, if so, whether such effects are dependent solely on statistical factors due to increases in density, the potential for actively-sought social interactions, or both. We found that the number of rats in an environment impacts ambulation speed, distance traveled, cluster formation and approaches, and that number and duration of clusters are highly dependent on the propensity for the rats to engage in social interactions.

Analysis of population distribution for anticipating radiological consequences of nuclear power plant program in West Kalimantan.

The potential establishment of a nuclear power plant (NPP) in the West Kalimantan is under consideration to address low electrification rates. This research assesses the demographic characteristics and population growth in the vicinity of the proposed NPP site in West Kalimantan. The investigation focuses on demographic aspects, population density, and anticipated growth during the operational phase of the reactor. The study area encompasses districts within a 25 km radius of the site. Employing a descriptive quantitative approach, this research integrates verified population data and utilizes spatial and temporal analysis. The exponential method is employed to forecast population growth throughout the operational lifespan of the reactor, to anticipate population increases in around NPP site. Reactor operation has potential radiological consequences. Results reveal that the suggested NPP site adheres to regulations concerning population density away from densely populated areas. Projected population growth is notable in specific regions, necessitating monitoring and policy attention. A gender-specific analysis highlights the higher female populations, with sensitivity to radiation exposure. These findings offer essential information for evaluating the radiological impact of the NPP on the population, so meeting NPP siting requirements. The study contributes valuable insights for decision-making regarding NPP development and safety considerations in West Kalimantan.

Urban population density and energy conservation: Empirical evidence from 276 cities in China.

Reducing urban energy consumption is a crucial step towards achieving sustainable urban development. Urban energy plays a fundamental role in urban development, and while previous studies have examined the relationship between population size and energy conservation, the impact of increasing population density on per capita energy consumption (PCEC) remains unclear. To achieve urban energy conservation in China, it is vital to comprehend this significant relationship. This study constructs a spatial regression model to examine the relationship between population density and PCEC using 9 years of balanced panel data from 276 cities to fill a gap in the literature. The results of spatial autocorrelation indicate a significant negative relationship and heterogeneity between population density and PCEC. The results of spatial regression show that for every 1% increase in population density, there is a subsequent increase in PCEC of 0.074%. Our findings suggest that lower PCEC correlation is associated with higher urban population density. This study can be a reference for policymakers seeking new energy conservation strategies for urban development.

Population abundance estimates in conservation and biodiversity research.

Measuring and tracking biodiversity from local to global scales is challenging due to its multifaceted nature and the range of metrics used to describe spatial and temporal patterns. Abundance can be used to describe how a population changes across space and time, but it can be measured in different ways, with consequences for the interpretation and communication of spatiotemporal patterns. We differentiate between relative and absolute abundance, and discuss the advantages and disadvantages of each for biodiversity monitoring, conservation, and ecological research. We highlight when absolute abundance can be advantageous and should be prioritized in biodiversity monitoring and research, and conclude by providing avenues for future research directions to better assess the necessity of absolute abundance in biodiversity monitoring.

Preliminary study of the population and reproductive dynamics of Echinaster sepositus (Spinulosida: Echinasteridae) in Cala del Racó / Estudio preliminar de la población y dinámica reproductiva de Echinaster sepositus (Spinulosida: Echinasteridae) en Cala del Racó

Abstract Introduction: The red starfish (Echinaster sepositus) is one of the most common asteroid species in the Mediterranean Sea. However, information about their biology or their role in benthic communities is scarce. Objective: This study aims to provide new information on the ecology of this species through the temporal characterization of the population of E. sepositus in Cala del Racó (Alicante, Spain) and the in situ monitoring of its reproductive cycle. Methods: For this purpose, three study areas were established at different depths. For each of the recorded starfish, data about the size, the substrate on which it was found, the area, the depth and the sex in the case of observing the reproduction were collected. Results: A total of 19 samplings have been carried out throughout a year of study. In this way, it has been possible to observe that the density of individuals increases in the shallower zone during autumn and winter, when the temperature drops to 14.13 ºC, while it decreases in spring and summer when the temperature rises to 27.17 ºC. Those results are reversed in the deepest part of the study. The highest density of individuals (0.51 ind/m2) occurred in October. Arborescent photophilic algae and crustose coralline algae were the substrates with the highest number of E. sepositus recorded. Medium to large specimens are located preferably on crustose coralline algae or arborescent photophilic algae, while smaller individuals were mostly located on Posidonia oceanica. No specimens of E. sepositus were observed spawning. Conclusions: Data leads to assume that there is a migration of starfishes towards more superficial areas when the water is at colder temperature and towards deeper areas when the temperature increases. It is valued the possibility that there is a change in the nutritional needs of E. sepositus throughout its development. According to our observations, the future reproduction studies should be concentrated between late-summer and early-autumn.

Resumen Introducción: La estrella de mar roja (Echinaster sepositus) es una de las especies de asteroideos más comunes del mar Mediterráneo. Sin embargo, la información sobre su biología o su papel en las comunidades bentónicas es escasa. Objetivo: Este estudio pretende aportar nueva información sobre la ecología de esta especie mediante la caracterización temporal de la población de E. sepositus en la Cala del Racó (Alicante, España) y el monitoreo in situ de su ciclo reproductivo. Métodos: Con este fin se establecieron tres zonas de estudio a distintas profundidades. Para cada una de las estrellas registradas se tomaron datos de tamaño, el sustrato sobre el que se encuentra, la zona, la profundidad y el sexo en caso de observar la reproducción. Resultados: A lo largo de un año de estudio se han realizado un total de 19 muestreos. De esta forma se ha podido observar que la densidad de individuos aumenta en la zona menos profunda durante otoño e invierno, cuando la temperatura del agua baja hasta los 14.13 ºC, mientras que se reduce en primavera y verano, cuando la temperatura se eleva hasta los 27.17 ºC. Este resultado se invierte en la zona más profunda del estudio. La mayor densidad de individuos ha sido observada en octubre (0.51 ind/m2). Las algas fotófilas arborescentes y las algas coralinales costrosas han sido los sustratos con un mayor número de E. sepositus registrados. Los ejemplares de tamaños medianos a grandes se localizan preferentemente sobre algas coralinales costrosas o algas fotófilas arborescentes, mientras que los individuos de menor tamaño se sitúan mayormente sobre Posidonia oceanica. No se observaron ejemplares de E. sepositus reproduciéndose. Conclusiones: Los datos permiten presuponer que existe una migración entre las zonas más superficiales, cuando la temperatura del agua es menor, y zonas más profundas cuando la temperatura aumenta. Se valora la posibilidad de la existencia de un cambio en los requerimientos nutricionales de E. sepositus a lo largo de su desarrollo. De acuerdo con nuestras observaciones, los estudios futuros sobre la reproducción de esta especie deben concentrarse entre finales de verano y principios de otoño.

Influence of Environmental Factors and Genome Diversity on Cumulative COVID-19 Cases in the Highland Region of China: Comparative Correlational Study.

BACKGROUND: The novel coronavirus SARS-CoV-2 caused the global COVID-19 pandemic. Emerging reports support lower mortality and reduced case numbers in highland areas; however, comparative studies on the cumulative impact of environmental factors and viral genetic diversity on COVID-19 infection rates have not been performed to date. OBJECTIVE: The aims of this study were to determine the difference in COVID-19 infection rates between high and low altitudes, and to explore whether the difference in the pandemic trend in the high-altitude region of China compared to that of the lowlands is influenced by environmental factors, population density, and biological mechanisms. METHODS: We examined the correlation between population density and COVID-19 cases through linear regression. A zero-shot model was applied to identify possible factors correlated to COVID-19 infection. We further analyzed the correlation of meteorological and air quality factors with infection cases using the Spearman correlation coefficient. Mixed-effects multiple linear regression was applied to evaluate the associations between selected factors and COVID-19 cases adjusting for covariates. Lastly, the relationship between environmental factors and mutation frequency was evaluated using the same correlation techniques mentioned above. RESULTS: Among the 24,826 confirmed COVID-19 cases reported from 40 cities in China from January 23, 2020, to July 7, 2022, 98.4% (n=24,430) were found in the lowlands. Population density was positively correlated with COVID-19 cases in all regions (ρ=0.641, P=.003). In high-altitude areas, the number of COVID-19 cases was negatively associated with temperature, sunlight hours, and UV index (P=.003, P=.001, and P=.009, respectively) and was positively associated with wind speed (ρ=0.388, P<.001), whereas no correlation was found between meteorological factors and COVID-19 cases in the lowlands. After controlling for covariates, the mixed-effects model also showed positive associations of fine particulate matter (PM2.5) and carbon monoxide (CO) with COVID-19 cases (P=.002 and P<.001, respectively). Sequence variant analysis showed lower genetic diversity among nucleotides for each SARS-CoV-2 genome (P<.001) and three open reading frames (P<.001) in high altitudes compared to 300 sequences analyzed from low altitudes. Moreover, the frequencies of 44 nonsynonymous mutations and 32 synonymous mutations were significantly different between the high- and low-altitude groups (P<.001, mutation frequency>0.1). Key nonsynonymous mutations showed positive correlations with altitude, wind speed, and air pressure and showed negative correlations with temperature, UV index, and sunlight hours. CONCLUSIONS: By comparison with the lowlands, the number of confirmed COVID-19 cases was substantially lower in high-altitude regions of China, and the population density, temperature, sunlight hours, UV index, wind speed, PM2.5, and CO influenced the cumulative pandemic trend in the highlands. The identified influence of environmental factors on SARS-CoV-2 sequence variants adds knowledge of the impact of altitude on COVID-19 infection, offering novel suggestions for preventive intervention.