Low Population Density Research Articles

Status assessment of a recently reintroduced eurasian lynx (Lynx lynx) population in the Palatinate Forest, South-West Germany

To reinforce Eurasian lynx populations in central Europe, 20 lynx from Slovakia and Switzerland were translocated to the Palatinate Forest between 2016 and 2020. Using a systematic camera trapping array consisting of 80 camera trapping sites in a 1,000 km² study area located in the centre of the approximately 1,800 km² Palatinate Forest, we aim to describe the status of the population in the final stages of the reintroduction project in winter and spring 2019/20 and 2020/21. We also use our data to provide a first estimate of population density of the newly established population. With an estimate of 0.52 independent individuals per 100 km², population density in the Palatinate Forest was still significantly lower than the densities of well-established reintroduced populations. The number of independent individuals detected in the study area decreased from 15 individuals in 2019/20 to 11 individuals in 2020/21, thus significantly below the number of lynx translocated. The low abundance in the Palatinate Forest can be explained by the dispersal of several individuals to the Vosges (France), which, together with the Palatinate Forest, form a continuous area of suitable lynx habitat of approximately 8,000 km². Our results may thus reflect the status of a young population that can expand over a potentially large area. Nevertheless, in light of the low population density, we strongly recommend a synchronized and harmonized transboundary monitoring program to keep track of the development of this important Franco-German lynx population. In case population density remains low, supportive measures need to be considered.

Multidimensional Evaluation Framework for Assessing Cultural Heritage Adaptive Reuse Projects: The Case of the Seminary in Sant’Agata de’ Goti (Italy)

As climate change accelerates, urban areas are becoming increasingly inhospitable, with rising heat island effects and overall unhealthy environmental conditions. In this context, historic villages, due to their proximity to nature and lower population density, can represent a valuable alternative to unsustainable urban areas, providing better quality of life (i.e., through healthier environment, better work–life balance). They are “populated” by historic buildings characterized by high cultural value but are often in a state of abandonment. Nowadays, the adaptive reuse of cultural heritage represents an efficient strategy to adapt it to new needs/requirements and, at the same time, to preserve its historical and intrinsic values for present and future generations. In this framework, this study proposes a multidimensional evaluation framework for assessing cultural heritage adaptive reuse projects, covering all sustainability dimensions and capturing both tangible and intangible values. This framework, consisting of multiple criteria and multidimensional indicators, has been applied to evaluate alternative scenarios related to the regeneration of the abandoned Seminary in Sant’Agata de’ Goti (historic village), Benevento, Italy. In particular, three different scenarios have been evaluated by the SOCRATES (SOcial multi Criteria Assessment of European policies) method, a multicriteria decision method developed by the Joint Research Center (JRC) of the European Commission.

Golden lion tamarin metapopulation dynamics five years after heavy losses to yellow fever.

The golden lion tamarin (GLT) is an Endangered primate endemic to Brazil's lowland Atlantic Forest. After centuries of deforestation and capture for the pet trade, only a few hundred individuals survived, all in isolated forest fragments 85 km from Rio de Janeiro city. Intensive conservation actions, including reintroduction of zoo-born tamarins, increased numbers to about 3700 in 2014. The most severe yellow fever epidemic/epizootic in Brazil in 80 years reduced two of the largest GLT populations by over 90%. Herein we report the results of a 2023 survey of GLTs designed to examine the dynamics of population recovery following yellow fever. Results indicate that populations hard hit by yellow fever are recovering due in part to immigration from adjacent forest fragments. No local extirpations were observed. About 4800 GLTs live in the survey area. This represents a 31% increase since the baseline survey completed in 2014. Two factors explain most of the increase: four large areas that had no GLTs or very low-density populations in 2014 are now at moderate density (three areas) or low density (one area), explaining 71% of overall increase since 2014. Increase in forest area within our survey area may explain up to 16% of the increase in GLT numbers since 2014. Results of computer simulations suggest that strengthening forest connectivity will facilitate metapopulation resilience in the face of mortality factors such as yellow fever.

Open-source data pipeline for street-view images: A case study on community mobility during COVID-19 pandemic.

Street View Images (SVI) are a common source of valuable data for researchers. Researchers have used SVI data for estimating pedestrian volumes, demographic surveillance, and to better understand built and natural environments in cityscapes. However, the most common source of publicly available SVI data is Google Street View. Google Street View images are collected infrequently, making temporal analysis challenging, especially in low population density areas. Our main contribution is the development of an open-source data pipeline for processing 360-degree video recorded from a car-mounted camera. The video data is used to generate SVIs, which then can be used as an input for longitudinal analysis. We demonstrate the use of the pipeline by collecting an SVI dataset over a 38-month longitudinal survey of Seattle, WA, USA during the COVID-19 pandemic. The output of our pipeline is validated through statistical analyses of pedestrian traffic in the images. We confirm known results in the literature and provide new insights into outdoor pedestrian traffic patterns. This study demonstrates the feasibility and value of collecting and using SVI for research purposes beyond what is possible with currently available SVI data. Our methods and dataset represent a first of its kind longitudinal collection and application of SVI data for research purposes. Limitations and future improvements to the data pipeline and case study are also discussed.

Demographic, socioeconomic, and health structure factors associated with the use of HIV pre-exposure prophylaxis in Brazil: A nationwide ecological study.

Aims: To assess the cumulative rate of HIV Pre-Exposure Prophylaxis (PrEP) users in Brazil since its 2018 implementation and to analyze the association between PrEP usage and state-level structural factors. Methods: A nationwide ecological study from 2018 to 2022 was conducted, examining the 5-year cumulative rate of PrEP users in relation to demographic, socioeconomic, and healthcare infrastructure variables. Multiple linear regression analysis identified significant predictors of PrEP utilization. Results: Between 2018 and 2022, 124,796 individuals used PrEP, with a cumulative rate of 61.5 per 100,000 population. The highest usage was in Minas Gerais, São Paulo, and Santa Catarina, while the lowest was in Distrito Federal, Maranhão, and Alagoas. Regression analysis showed that higher PrEP usage was associated with lower population density, a younger median age, a lower male to female ratio, and reduced social vulnerability. Additionally, PrEP usage was positively associated with the density of medical doctors and the number of dispensing units. Conclusions: The study reveals significant regional disparities in PrEP usage across Brazil, influenced by socioeconomic and healthcare factors. It highlights the need for targeted public health strategies to enhance PrEP access and uptake, especially in socially vulnerable regions.

Population density effects on gamete traits and fertilisation dynamics under varying sperm environments in mussels.

Gamete traits can vary widely among species, populations and individuals, influencing fertilisation dynamics and overall reproductive fitness. Sexual selection can play an important role in determining the evolution of gamete traits with local environmental conditions determining the strength and direction of sexual selection. Here, we test for signatures of post-mating selection on gamete traits in relation to population density, and possible interactive effects of population density and sperm concentration on sperm motility and fertilisation rates among natural populations of mussels. Our study shows that males from high-density populations produce smaller sperm compared with males from low-density populations, but we detected no effect of population density on egg size. Our results also reveal that females from low-density populations tended to exhibit lower fertilisation rates across a range of sperm concentrations, although this became less important as sperm concentration increased. Variances in fertilisation success were higher for females than males and the effect of gamete compatibility between males and females increases as sperm concentrations increase. These results suggest that local population density can influence gamete traits and fertilisation dynamics but also highlight the importance of phenotypic plasticity in governing sperm-egg interactions in a highly dynamic selective environment.

The Spatio-Temporal Distribution of Suicide-related Emergency Calls in a European City: Age and Gender Patterns, and Neighborhood Influences.

Objective: The aim of this study was to conduct a comprehensive spatio-temporal analysis of suicide-related emergency calls in the city of Valencia (Spain) over a six-year period. To this end we first examined age and gender patterns and, second, the influence of neighborhood characteristics on general and gender-specific spatio-temporal patterns of suicide-related emergency calls. Method: Geocoded data on suicide-related emergency calls between 2017 and 2022 (N = 10,030) were collected from the 112 emergency service in Valencia. Data were aggregated at the census block group level, used as a proxy for neighborhoods, and trimesters were considered as the temporal unit. Two set of analyses were performed: (1) demographic (age and gender) and temporal descriptive analyses and (2) general and gender-specific Bayesian spatio-temporal autoregressive models. Results: Descriptive analyses revealed a higher incidence of suicide-related emergency calls among females and an increase in calls among the 18-23 age group from 2020 onwards. The general spatio-temporal model showed higher levels of suicide-related emergency calls in neighborhoods characterized by lower education levels and population density, and higher residential mobility, aging population, and immigrant concentration. Relevant gender differences were also observed. A seasonal effect was noted, with a peak in calls during spring for females and summer for males. Conclusions: These findings highlight the need for comprehensive mental health targeted interventions and preventive strategies that account for gender-specific disparities, age-related vulnerabilities, and the specific characteristics of neighborhoods.

FOREST AND ITS RESOURCES IN PRE-COLONIAL MIZORAM

Northeastern Indias Mizoram state is landlocked and surrounded by Bangladesh on the west and Myanmar on the east and south. It shares boundaries with Manipur and Assam to the north, and with Tripura to some extent to the west. The hill forests are an essential resource that indigenous groups rely on for their way of life. Because of the biomass these trees produced and the occasional removal of those woods for farming, Mizorams livelihoods were formerly totally depended on those forests. More precisely, jhuming was the only source of income for the pre-colonial Lushai civilization, with some hunting and gathering providing additional support. Thus, forest land is a pivot around which the peoples lives revolve their hunting, festivals, farming, and migration patterns all center on the area they own. People in traditional societies rely heavily on wild plants for sustenance, medicine, and leisure. That was especially true during the pre-colonial era, when the majority of items used were made of vegetative materials that could be found in the nearby forest. The sociocultural resource domain appeared to be limitless to the early inhabitants. There was not much competition for space because of the incredibly low population density.

A Territorial Strategy for the Activation of Tourism in Low Population Density Heritage Landscapes

Sustainable and balanced territory development involves management and planning based on the cultural and natural values that characterise it. In contrast to solutions based exclusively on quantitative growth, today, we defend qualitative territorial planning based on specific characteristics and identity what, ultimately, is the heritage content and significance of the territory. In line with these arguments, this article reflects on the need to design territorial planning strategies to activate territories with low demographic density through their heritage and landscape values, specifically referring to rural areas made up of small, scattered population centres. The wide territorial dispersion of these settlements, which represent a large proportion of Latin American and European territory, calls for specific planning and management models and criteria. This article proposes a territorial strategy for these sites aimed at sustainable tourism activation through itineraries and potential identity facilities. The application of the strategy is shown in a pilot case study of the island of Fuerteventura (Canary Islands, Spain).

The magnitude of Allee effects varies across Allee mechanisms, but not taxonomic groups

The Allee effect is a density‐dependent phenomenon in which individual fitness increases as population density increases at low population densities. Over the past few decades, a growing number of studies have identified Allee effects in populations using experimental approaches and statistical modeling techniques. These studies have investigated multiple Allee mechanisms (e.g. mate‐finding, predation, resource limitation), across a range of systems and taxa (e.g. plants, vertebrates, invertebrates). This meta‐analysis aims to synthesize studies that experimentally manipulated population density and measured either per capita population growth or fitness components, with the goal of determining whether the ‘magnitude' of the Allee effect (defined here as the positive correlation between population density and population growth or fitness) varies with Allee mechanism across taxonomic groups. A total of 2305 studies were screened, and 62 of these studies met our meta‐analysis inclusion criteria. Within these 62 studies, 155 effect sizes encompassing nine different Allee mechanisms were identified across five broad taxa. When grouped by Allee mechanism and taxa, the magnitude of the Allee effect differed across mechanisms, whereas taxonomic group was less useful at explaining variation in the magnitude of Allee effects. Of the nine Allee mechanisms identified, interspecific competition was associated with the largest Allee effects, followed by fear, pollen limitation and mate limitation. These findings suggest that Allee effects may be more dependent on mechanism than taxa and may function similarly within different taxonomic groups. However, as the majority of experimental Allee effect studies included in this meta‐analysis focused on plants and invertebrates, more research is needed on Allee effects in other taxonomic groups to confirm this conclusion. This first quantitative synthesis of Allee effect research in ecology offers novel insight into how Allee mechanisms affect the manifestation of Allee effects in populations, providing important information for ecologists and conservationists.

Effect of cotton population density on lint yield and fiber quality

AbstractCommercial cultivars with advanced technology have reduced pest pressures, while greater seed costs have increased total production cost. Limited information is available on the optimal final population density (PD) for the commercially available cotton (Gossypium hirsutum L.) cultivars with advanced technologies in water‐scarce environments. Therefore, our objectives were to examine the effects of PD on cotton growth and development, lint yield, fiber quality, and net return. A 2‐year study was conducted to test four PDs (low, medium, high, and very high) in deficit‐irrigated and dryland conditions at Chillicothe, TX. Final PD at 12 days after planting were 54,078, 109,563, 124,037, and 151,377 plant ha−1 in irrigated and 67,346, 115,335, 116,397, and 145,432 plant ha−1 in dryland trials. Maturity was delayed in the low PD early in the season; however, the differences on maturity ceased toward the end of the season. No statistical differences were observed on lint yield and fiber quality among treatments in irrigated and dryland trials. Average lint yields were 1199 kg ha−1 in irrigated and 796 kg ha−1 in dryland trial. Net returns were similar among all PD in the irrigated trial, while low PD had significantly higher net‐return than very high PD in the dryland trial. The higher net return at the low PD was due to the lower seed cost associated with a low seeding rate. In the water‐scarce environment, final plant density of 54,078 plant ha−1 in deficit irrigation and 67,346 plant ha−1 in dryland produced optimal yield and net return as compared to higher PD examined.

Pediatric anesthesia in Mongolia and Thailand.

In Mongolia, pediatric anesthesia has advanced during the past 25 years through expanded, standardized education programs and international collaboration. Pediatric anesthesia is a recognized specialty, covering all surgical services, including cardiac and transplant, using physicians and nurses. The pediatric anesthesia fellowship is 6 months after 2 years of residency; pediatric nurse anesthesia training is 6 months. As a Low- and Middle-Income Country (LMIC) with low population density and extreme weather, the challenges include insufficient equipment, supplies, and clinician numbers, matching few clinicians to many varied patient locations, and covering surgical emergencies over distance and weather. In Thailand, education and training in pediatric anesthesia remain a focus: Pediatric anesthesia is an official subspecialty, the fellowship is accredited, using a competency-based curriculum with milestones of Direct Observation of Procedural Skills and Entrusted Professional Activities. The Bangkok Anesthesia Regional Training Center (BARTC)-Pediatrics, jointly sponsored by the World Federation of Societies of Anesthesiologists (WFSA) and the Society for Pediatric Anesthesia (SPA), have expanded training to anesthesiologists worldwide. Challenges include difficulty balancing service workload and education, as well as attracting pediatric anesthesia fellows due to the strong private sector job market.

First evidence of anthropogenic TiO2 nanoparticles occurrence in Chilean rivers

This study marks the first recorded case of TiO2 nanoparticle pollution in Chilean rivers, indicating significant progress in understanding the distribution of nanowaste and its effects on a global scale. By investigating four different locations, including the outlet of a wastewater treatment plant during summer, winter and spring, the research revealed varied concentrations of TiO2 nanoparticles, with a notable range between 17.6 µg L−1 during the summer and 22.9 µg L−1 in spring in downstream river sections. The study used transmission electron microscopy to characterize nanoparticles, observing sizes between 10 and 206 nm, and an EDS detector confirmed titanium proportions of 4.84 % to 20.35 % by dry weight. These TiO2 nanoparticles, predominantly in Rutile and Anatase forms, denote a significant environmental presence, especially considering the low population densities of the sampling areas. The findings highlight the urgent need for international awareness and routine monitoring of nanowaste, advocating for preventive actions in the production of nanomaterials and adaptive management strategies in tune with the dynamic nature of water systems and environmental changes, both for places densely and sparsely populated.

Urban roadkill assessment in Vienna reveals low incidence rates

Abstract. An important factor in the decline of global animal diversity is road traffic, where many animals are killed. This study aimed to collect data on vertebrate roadkill in the city of Vienna, Austria, between 2017 and 2022 using three different approaches: citizen science, systematic monitoring by bicycle along a 15 km route, and systematic monitoring on foot along a 3 km route. During 359 monitoring events, only four roadkill incidences (three Erinaceus sp., one Rattus sp.) were found by bicycle or on foot. At the same time citizen scientists reported 1 roadkill squirrel on the bicycle route and 84 roadkill incidences for the entire city area. Hedgehogs and urban birds were commonly reported species by citizen scientists. Although no amphibian or reptile roadkill was found during systematic monitoring, they were reported by citizen scientists. The low number of roadkill incidences found suggests a potentially low population density that makes the impact of roadkill even more severe – a hypothesis that should be further investigated amidst the global decline in biodiversity.

Biochar from recovered cellulose as new admixture in constructed wetlands for micropollutant removal: A circular approach

This study aimed to evaluate the suitability of biochar produced by pyrolysis from recovered wastewater cellulose and activated biologically as an admixture in Constructed Wetlands (CWs) when applied as a post-treatment step to remove micropollutants (MPs) from municipal wastewater effluent. Two planted vertical flow mesocosm CWs with cellulose-based admixtures of different origins (plant residue and recovered toilet paper) were fed with a municipal wastewater effluent representative for rural catchments. The results showed an average MPs elimination of 89.1 % for the activated biochar produced from recovered cellulose when 15 relevant compounds are considered and a reduction of the risk from compounds cocktail below the maximum acceptable level having diclofenac, carbamazepine, PFOS, ciprofloxacin and clarithromycin as main risk drivers (Risk Quotient > 1). The implementation of a circular approach to reduce MPs was finally conducted for the Blies catchment (Saarland region in Germany) characterized by low population density and small, sensitive water bodies. This approach demonstrates the feasibility of combining cellulose recovery with a fine sieve in large wastewater treatment plants (WWTPs) and providing biochar produced from recovered cellulose as an admixture to small WWTP where CW is an affordable solution for MP mitigation.

Urban structure types and students’ academic performance

ABSTRACT In this study, we propose a novel approach for estimating the relationship between neighborhood characteristics and students’ academic performance. We propose the concept of urban morphology by Urban Structure Types (USTs). USTs are spatial indicators that describe the urban system through its physical, environmental, and functional characteristics. Our academic performance data includes 344,175 students from 256 public schools in the Federal District (FD), Brazil. This is student-level academic achievement data from 2017 to 2020. We performed the UST mapping in the FD by using visual interpretation. We classified 21 different types of UST. We fit mixed-effects regression models with a student-specific random intercept and slope. The model was adjusted for temporal factors, SES factors, and variables representing the characteristics and the location of each school. Our findings suggest associations between several types of USTs surrounding schools and academic performance. Overall, areas characterized as low population density, with high green index, and high standard residences were associated with an increase in student performance. In contrast, areas that include old buildings near streets, with significant traffic density, and areas with significant exposed soil (areas devasted) were associated with a decrease in student performance. The results of our study support the creation of effective educational and urban planning policies for local interventions. These interventions are likely to translate into healthier schools and improvements in children's behavioral development and learning performance.

The socioeconomic epidemiology of inherited retinal diseases in Portugal

BackgroundInherited retinal diseases (IRDs) are a group of rare degenerative disorders of the retina that can lead to blindness from birth to late middle age. Knowing the target population and its resources is essential to better plan support measures. The aim of this study was to evaluate the socioeconomic characteristics of regions in Portugal where IRD patients reside to inform the planning of vision aid and rehabilitation intervention measures.ResultsThis study included 1082 patients from 973 families, aged 3 to 92 years, with a mean age of 44.8 ± 18.1 years. Patients living with an IRD were identified in 190 of the 308 municipalities. According to this study, the estimated IRD prevalence in Portugal was 10.4 per 100,000 inhabitants, and by municipalities, it ranged from 0 to 131.2 per 100,000 inhabitants. Overall, regions with a higher prevalence of IRD have a lower population density (r=-0.371, p < 0.001), a higher illiteracy rate (r = 0.404, p < 0.001) and an overall older population (r = 0.475, p < 0.001). Additionally, there is a lower proportion of doctor per capita (r = 0.350, p < 0.001), higher social security pensions beneficiaries (r = 0.439, p < 0.001), worse water quality for human consumption (r=-0.194, p = 0.008), fewer audiences at the cinema (r=-0.315, p < 0.001) and lower proportion of foreign guests in tourist accommodations (r=-0.287, p < 0.001).ConclusionThe number of identified patients with IRD varied between regions. Using data from national statistics (PORDATA), we observed differences in socioeconomic characteristics between regions. Multiple targeted aid strategies can be developed to ensure that all IRD patients are granted full clinical and socioeconomic support.

Two-Stage Delivery System for Last Mile Logistics in Rural Areas: Truck–Drone Approach

In rural areas of China, the challenges of efficient and cost-effective distribution are exacerbated by underdeveloped infrastructure and low population density, with last mile logistics distribution posing a significant obstacle. To address the gap in drone application for last mile logistics in rural areas, a truck–drone distribution model was developed based on the specific conditions of rural regions. The improved fuzzy C-means algorithm (FCM) and genetic simulated annealing algorithm (GASA) were employed to tackle real−world cases in rural areas. The focus of the truck–drone system is to optimize the rural logistics distribution process, reduce delivery time, and minimize costs while considering factors such as maximum mileage of trucks and drones as well as customer priority. Compared to traditional methods, this system has demonstrated notable improvements in distribution efficiency and cost reduction, offering valuable insights for practical drone applications in last mile rural logistics.

Disabilities of the patients, visiting the children’s clinic, at the regional center of the subarctic territory with low population density

A retrospective observational continuous cohort study includes an analysis of diseases that caused the onset of primary disability in 174 children of “SChCl No.3” and diseases that caused the onset of disability in 1690 children with disabilities in 2019-2021. A comparative analysis was carried out: the main dysfunctions in the state of health of children with disabilities and the leading limitations of life in the state of health of children with disabilities. (The control groups consisted of 231 children of “SChCl No.3” who received a disability for the first time and 1611 patients who were disabled in 2011-2018).

Longitudinal population dynamics of Mediterranean-Atlantic Arbutus during the last 30 ka

The current distribution of the genus Arbutus in the Old World prompts questions about its long-term population dynamics, location and extent of refuge areas, and modern vulnerability in relation to climate change and human activity. Our work aims to address these questions by combining modern occurrence data with a comprehensive survey of pollen and macrofossil records. Range maps of past distribution have been produced for the last 32 ka to investigate geographical trends in population dynamics and the timing of the appearance of Arbutus across different biogeographical regions. In the Atlantic domain, Arbutus has been consistently present during the last 32 ka, even during the Last Glacial Maximum. In the central and eastern Mediterranean regions, it progressively increased since the beginning of the Holocene, appearing along the coasts of the Black Sea and in the Levant during the Middle Holocene. In addition, the dynamics of Arbutus in a number of peripherals stands (Ireland, Canary Islands, Cyrenaica, Crimea, and Black Sea coasts) is discussed. The palaeobotanical evidence suggests that the delayed emergence of eastern populations and peripheral stands in the fossil record may be ascribed to a very low population density, rather than to a sequential migration process from the western sectors of the range. The comparison of fossil records and modern occurrences highlights an overall temporal continuity between long-term persistence areas and current centers of gravity and calls for density-weighted ecological models that may contribute to an informed assessment of conservation actions and strategies.