Increasing Population Density Research Articles

Livelihood adaptation to changes in River Ekulu depth, channel width and riverbank vegetation cover type by household breadwinners in selected communities in Enugu, Nigeria

Nigeria and most other developing countries need to explore using socio-ecological approaches to address some ecosystem challenges. Changes in river depth, channel width and riverbank vegetation cover type of River Ekulu in Enugu, Nigeria, their causes and effects on biodiversity and livelihood adaptation by household breadwinners, who depended on the river for livelihood activities, were investigated. Snowball sampling technique was adopted. Causes of changes in the river depth, channel width and riverbank vegetation cover type and their effects on biodiversity and livelihood adaptation were obtained from literature with Google Forms administered to purposively selected experts. Factor component analysis was used to select the significant ones. Aerial images of the river were captured with a drone. Questionnaire was used to elicit information from the target household breadwinners to corroborate the images or otherwise, the causes and the effects of the changes on biodiversity and livelihood adaptation. Data were analyzed to test seven null hypotheses bordering on the objectives of the study. Results showed that the observed changes led to adverse effect on biodiversity and the attendant imperative livelihood adaptation. Factors causing the changes in the river depth, width and riverbank vegetation cover type were climate change (factor weight, fw, 0.44–0.54) and increase in population density (fw 0.46–0.63). Recommendations include conscientisation of government and riverine neighbourhood dwellers on the observed ecological changes, their causes and effects, and ways-forward on policies and practices.

The effects of human population density on trophic interactions are contingent upon latitude

AbstractAimGlobal‐scale studies are necessary to draw general conclusions on how trophic interactions vary with urbanization and to explore how the effects of urbanization change along latitudinal gradients. We predict that the intensity of trophic interactions decreases in response to urbanization (quantified by human population density). Since trophic interactions are more intense at lower latitudes, we also expect major impacts of urbanization at higher latitudes, where base levels are essentially lower.LocationGlobal (881 study sites).Time period2000–2021.Major taxa studiedBirds, arthropods and woody plants.MethodsWe compiled global data on insect herbivory and bird predation from studies that employed similar methods and fitted generalized linear mixed models to test how these trophic interactions vary with human population density, latitude and their interactions.ResultsThe intensity of herbivory and predation decreased with an increase in human population density at lower latitudes. Surprisingly, it remained unaffected at intermediate latitudes and even increased at higher latitudes.Main conclusionsThe observed patterns may be attributed to local climate changes in urban areas, such as the Urban Heat Island effect, which disrupts thermal stability in the tropics while increasing niche availability at polar latitudes.

The evolutionary stability of partial migration with Allee effects

An Allee effect is a density-dependent phenomenon in which population growth or individual components of fitness increase as population density increases. Understanding the density-dependent effects is vital to elucidate how populations evolve and to investigate evolutionary stability. Partial migration, where a proportion of a population migrates while other individuals remain resident, is widespread across most migratory lineages. However, the mechanism still needs to be better understood in most taxa, especially those experiencing positive density-dependent effects. Here we investigate the evolutionary stability of a partial migration population with only the migrant population experiencing Allee effects. Using the Evolutionary Game Theoretic (EGT) approach, we prove the existence and uniqueness of an evolutionary stable strategy (ESS). EGT provides a mathematical framework for understanding and modelling Darwinian evolution by natural selection. We also show that the ESS is the only Ideal Free Distribution (IFD) that arises in the context of a partially migrating population in a two-habitat environment.

A flash in the pan? The population dynamics of a dominant pioneer species in tropical dry forest succession

AbstractGlobally, around half of all tropical forests are secondary communities which are recovering from previous disturbances. In these communities, dominant pioneers play a critical role in the successional dynamics due their ability to modify the environment, and thus to facilitate or hinder the performance of other species. In this study, we examined the population dynamics of the dominant pioneer species, Mimosa acantholoba var. eurycarpa, in a tropical dry forest during the process of secondary succession. We collected data from permanent plots over a period of 13 years and used integral projection models to analyze the vital rates and changes in population size. Most vital rates were negatively related to successional age, with resprouting, survival and recruitment of individuals responding more strongly, and individual growth rate more weakly. These vital‐rate trends translated into significant variation of population size over succession, with a maximum size at year four and a rapid decline thereafter. Overall, our findings suggest that this species benefits from its ability to display a large number of resprouts in very early stages of succession, contributing to the rapid increase in population density. However, as succession unfolds, a lack of resprouting and a decline in survival reduce its population size, to the point of local extinction. These results highlight the importance of resprouting in the early dynamics of tropical dry forest communities recovering from disturbance.

Pesticide Pressure on Insect and Human Population: A Review

It is estimated that the current 7 billion world population would increase by 70 million people year, or 30%, to reach 9.2 billion by 2050. It is anticipated that this increased population density will result in a 70% rise in the demand for food production. This increase is mostly attributable to shifts in emerging countries' dietary trends toward higher-quality foods, such as increased consumption of meat and dairy products and the growing use of cereals for animal feed. There isn't much more agricultural land available. Any growth will primarily come at the price of forests and other natural ecosystems that support wildlife, wild cousins of crops, and organic pest adversaries. Additionally, rather than producing food, more agricultural land will be used to create bio-based commodities like fiber and biofuel. As a result, we must produce food on even less area, with even less water, and with less energy, pesticides, and fertilizer than we do now. There is an urgent need for sustainable production at elevated levels in light of these constraints. Reducing the present output losses resulting from pests is a significant obstacle to agricultural productivity. This review covers pest-related crop losses worldwide, estimates of productivity linked to pesticide use, costs and benefits of pesticide use, chemical yield loss reduction strategies, biological and recombinant pest control methods, and the difficulties facing the crop protection sector. In deciding how pesticides will be used in agriculture in the future, the general public plays a crucial role. However, the external issues related to the impacts of pesticides on human and environmental health must also be addressed as long as there is a need for pesticide-based solutions to pest management issues and food security concerns.

Antimicrobial peptide cecropin B functions in pathogen resistance of Mythimna separata.

Mythimna separata (Lepidoptera: Noctuidae) is an omnivorous pest that poses a great threat to food security. Insect antimicrobial peptides (AMPs) are small peptides that are important effector molecules of innate immunity. Here, we investigated the role of the AMP cecropin B in the growth, development, and immunity of M. separata. The gene encoding M. separata cecropin B (MscecropinB) was cloned. The expression of MscecropinB was determined in different developmental stages and tissues of M. separata. It was highest in the prepupal stage, followed by the pupal stage. Among larval stages, the highest expression was observed in the fourth instar. Tissue expression analysis of fourth instar larvae showed that MscecropinB was highly expressed in the fat body and haemolymph. An increase in population density led to upregulation of MscecropinB expression. MscecropinB expression was also upregulated by the infection of third and fourth instar M. separata with Beauveria bassiana or Bacillus thuringiensis (Bt). RNA interference (RNAi) targeting MscecropinB inhibited the emergence rate and fecundity of M. separata, and resulted in an increased sensitivity to B. bassiana and Bt. The mortality of M. separata larvae was significantly higher in pathogen plus RNAi-treated M. separata than in controls treated with pathogens only. Our findings indicate that MscecropinB functions in the eclosion and fecundity of M. separata and plays an important role in resistance to infection by B. bassiana and Bt.

Litter accumulation suppresses grass production but facilitates shrub expansion in a long‐term fenced grassland

AbstractShrub expansion is increasing in grasslands worldwide and has profound effects on biodiversity and ecosystem functions. Shrub expansion has primarily been explained by extrinsic factors such as climate change and human activities, yet the roles of intrinsic shrub demographic population dynamic and shrub–grass interaction remain poorly understood. With a paired mown and exclosure comparison experiment and baseline levels of shrub abundance in a semiarid grassland, we confirmed that long‐term livestock exclusion promotes expansion of two native shrubs, Artemisia sacrorum and Caragana brachypoda. Shrub abundance increased during the livestock exclusion period. Shrub biomass in fenced plots was about 5‐ to 10‐fold greater than in mown plots. Both increase in population density and individual size (especially height) contributed to shrub increase. The mechanism behind this was the divergent effects of litter accumulation on shrubs and grasses. Litter accumulation suppressed grass production, while facilitating shrub recruitment and growth. Our findings highlight the potential role of litter accumulation‐mediated shifts in shrub–grass interactions, which should be incorporated into grazing top‐down control to better predict the restoration outcomes of grassland management changes. The identified internal biotic mechanism raises the possibility that removal of accumulated litter by grazing or mowing may be an alternative way to maintain or restore a grass‐dominated state in shrub expansion areas.

Urban occupation and surface runoff in cities: a study case in Piracicaba - SP

This study analyzes how uncontrolled human occupation can negatively impact surface runoff conditions in urban environments. For this purpose, the study assesses the correlation between rainfall, Piracicaba River flow and the urban occupation growth regarding the incidence of floods in Piracicaba-SP. To address the research question: Is the increase in flooding caused by the increased population density? The following data was used: flow and precipitation data in the urban perimeter, obtained from the Piracicaba Water and Electricity Department; population and density data from five neighborhoods based on the "Google Earth Pro" software, covering sixteen years of study. The findings indicate that three districts experienced increased flooding, while two other well-established districts did not encounter significant changes in flood frequency.

A Seasonal Analysis of the Quality of and Safety of Drinking water harnessed from Roadside Entombments in East Rural, St. Andrew Jamaica

Due to the increase in population density in urban areas and the uncertainty associated with the availability of municipal water supplies, roadside water entombments have remained an important water source for many residents of Jamaica. This research focused on the seasonal, quality and safety of water harnessed from two non -municipal roadside water supplies. The study employs a cross sectional quantitative approach and uses international and national water quality standards as the benchmark. The aim of the study was to describe the seasonal quality and safety of water harnessed from roadside water entombments in East Rural St. Andrew Jamaica. The physiochemical, microbiological quality and safety of the water supplies were assessed. Two microbiological samples were collected from each source during the wet and dry months. In 100 % of the microbiological samples the Total Coliform levels exceeded national and international limits of Zero CFU/L for safe drinking water.

Research on smart city public health detection system and improvement technology based on intelligent multi-objective.

With the increase of urban population density, urban sanitation becomes more severe; urban sanitation has important influence on public health. Therefore, in order to realize the detection of public health in smart cities, the research will use cutting-edge scientific and technological methods to improve urban environmental health, so as to promote the realization of public health achievements. This study introduces public health detection and optimizationtechnologies for smart cities. Firstly, a data detection system for urban public health environment was established using sensors and intelligent multi-objective technology to evaluate the water quality, air quality, and noise level of the city. Then, an intelligent garbage management system based on Tensor-flow was constructed to achieve efficient garbage collection and treatment. Finally, an intelligent traffic management system was developed to monitor and regulate urban traffic flow. The results of the simulation experiment demonstrated that the life data detection system was operationally stable, with a high success rate of 98%. Furthermore, its accuracy in detecting residents' living environment data was above 95%, the maximum relative error was only 0.0465, making it a reliable and efficient tool. The waste recycling system achieved a minimum accuracy of 83.6%, the highest accuracy rate was 95.3%, making it capable of sorting and recycling urban waste effectively. Additionally, the smart traffic management system led to a 20% reduction in traffic congestion rates, 20 tonnes less tailpipe emissions and an improvement in public health and well-being. In summary, the plan proposed in this study aims to create a more comfortable, safe, and healthy urban public health environment, while providing theoretical support for environmental health management in smart cities.

Examining the impact of revenue diversity on government productivity using stochastic frontier production function: the U.S. State government

ABSTRACT This study empirically examines the impact of revenue diversity on government productivity across U.S. states via a two-step system generalized method of moments (GMM) estimation during a 41-year period (1980–2020). Government productivity is driven by revenue diversity, economic growth, fiscal health, and population density. In particular, increasing revenue diversity promotes state governments’ productivity, supporting our hypothesis. This result holds even after the mortgage crisis. These new findings suggest that states can enhance their productivity by expanding their revenue sources. Economic growth and rising fiscal health foster government productivity; these results apply after the mortgage crisis as well. An increase in population density also boosts government productivity during the study period. Climbing tax burdens undermine productivity, whereas growth in long-term debt facilitates productivity after the mortgage crisis. This study defines and expands the concept of productivity in U.S. state governments and explores influencing factors. Subsequent research can build on this theoretical model by integrating other variables tied to government productivity.

Do degraded grasslands provide a better habitat for plateau pika? —Testing the nutritional hypothesis

Besides overgrazing by livestock, browsing by small native mammals, such as plateau pikas, is considered an important cause of alpine grassland degradation on the Qinghai-Tibetan Plateau (QTP). Preference of pikas for degraded grasslands, resulting in increased population density, has been proposed as the most accepted hypothesis. However, few studies have explored the mechanisms underlying the habitat preferences of pikas. Herein, we analyzed aboveground biomass, community composition, forage quality of lightly and severely degraded alpine grasslands, and the diet and nutritional intake of pikas living there to test whether the plant community structure and associated nutrient composition of severely degraded grasslands are more suitable for pikas in terms of dietary and nutritional requirements. Our results showed that the plant community structure differed between lightly and severely degraded grasslands, with lightly degraded grasslands containing more food plants preferred by pikas. The nutritional composition of plants in severely degraded grasslands was less suitable for pikas than that in lightly degraded grasslands. Our results reject the nutritional hypothesis that severely degraded grasslands meet the dietary and nutritional needs of pikas better. We conclude that food and nutrient selection are not drivers of population increase in pikas in the severely degraded grasslands of the QTP.

Analyzing Role of FSI in City Sprawl- Case Study: Pune City

Pune is the second-largest city in the state of Maharashtra after Mumbai, and is an important city in terms of its economic and industrial growth. Over the years Pune Municipal Corporation area has grown in concentric rings. Future growth of PMC will be mainly governed by existing transport corridors, existing and future industrial developments in and around PMC and the expansion of central business district (CBD). The aim of the research is to analyze role of FSI in city sprawl supported with a case study of Pune City. The objectives of the research are- to assess existing and proposed policies/projects undertaken in Pune City for last two decades, to understand population growth trend and its distribution within and around the city, to analyze factors contributing to intensification and spatial distribution of population density, to examine the effects of increased population density on the existing infrastructure facilities in the urban settlements and lastly to propose strategies or proposals for the selected study area. The methodology adopted for the study initiates with assessing the data collected from secondary sources. The increase in population and built-up area attributed to various factors are studied using satellite images and GIS techniques. Population and built-up density can be linked up together to understand how the former growth affects the latter. The distribution and pattern of population density helps to provide useful information in provision of necessary service infrastructure. Finally, different approaches of accommodating the future population are studied and proposed in the study. Keywords Urban sprawl; Density; Spatial Distribution; Accessibility; Urban Growth

Spatial Process Analysis of the Evolution of Farmland Landscape in China

Accurately identifying the patterns of evolution in farmland plays an important role in optimizing farmland management. The aim of this study is to classify the evolution patterns of farmland in China and explore related mechanisms, providing a reference for constructing a systematic farmland management plan. Using land cover data from five periods in China, nine types of farmland evolution process are described and identified based on landscape process models. We analyzed these processes’ spatiotemporal dynamics and, by examining regional variations, achieved a zoned mapping of China’s farmland evolution. In this study, we combined natural and socioeconomic factors to analyze the mechanisms driving the evolution of farmland landscapes in China. The results indicated that from 1980 to 2020, areas of both lost and restored farmland showed a trend of first increasing and then decreasing, while the total area of farmland fluctuated. The remaining farmland types consisted mainly of core and edge. Their distribution was similar to that of the major agricultural regions in China. Expansion was the main means of farmland restoration. Farmland fragmentation was widespread, and, over time, it became increasingly severe. Shrinkage and subdivision dominated the farmland fragmentation. Altitude and slope had the greatest impact on the evolution patterns of farmland. Increasing urban industrialization and an increase in population density led to an increase in the demand for food production, which placed greater demands on the farmlands in the region. The farmland evolution pattern is a result of the interactions among multiple factors.

Spatiotemporal pattern evolution and influencing factors of population spatial distribution in Changsha-Zhuzhou-Xiangtan urban agglomeration, China

<p class="MsoNormal" style="text-align: justify;"><span lang="EN-US" style="font-family: 'times new roman', times, serif; font-size: 14pt;">Population, as a fundamental element in urban development, often reflects a city's economic development pattern through its spatial distribution and dynamic changes. Studying population spatial distribution is pivotal for bolstering the economic activity capacity in urban agglomerations and guiding regional economic health. Using the Changsha-Zhuzhou-Xiangtan urban agglomeration as a case study, this paper analyzes its overall spatial structure and the spatiotemporal evolution of population at the district and county levels. This analysis utilizes population density, population redistribution index, and population geographic concentration as key indices. Additionally, a spatial econometric model is constructed to assess the impact of economic, social, and environmental factors on population spatial patterns. Findings reveal several key points: (1) Furong District serves as the primary central area, boasting a population geographic concentration of 25.1% in 2021. Tianxin District, Kaifu District, Yuhua District, Shifeng District, Yuelu District, and Hetang District constitute the secondary central areas, while Yutang District, Tianyuan District, Lusong District, Yuhu District, Wangcheng District, and Changsha County form the tertiary level areas. (2) Population density within the Changsha-Zhuzhou-Xiangtan urban agglomeration gradually decreases from Furong District outward. The first central area and sub-central areas experience increasing population density, highlighting a polarization trend in the population distribution. (3) The overall Moran's index for the spatial distribution of population in the Changsha-Zhuzhou-Xiangtan urban agglomeration is significantly positive, indicating a strong spatial autocorrelation and a deepening spatial agglomeration of population distribution. (4) Per capita disposable income, financial expenditure, and education level positively influence the geographical concentration of population in the urban agglomeration, while GDP per capita, road area per capita, and environmental quality exert a negative impact. Notably, the most influential factors shaping population spatial distribution are GDP per capita, disposable income per capita, and air quality.</span></p>

Smallholder Farmers' Local Practices Underpinning the Use of Agroforestry Technologies in Uganda's Mt. Elgon Region

Mt. Elgon is a unique cross-border afro-montane ecosystem that has always provided vital essential goods and services for human livelihoods. However, with the increasing population density, forest degradation has become a significant issue, resulting in a rise in landslides, mudslides, pest and disease outbreaks, and reduced land productivity. Recently, it has been realized that many smallholder farmers have incorporated trees into their farming systems using indigenous knowledge, indicating their profound knowledge regarding tree use and management has reminded us that farmers have always been privy to much information regarding tree use and management accumulated over the years. This study aims to investigate how smallholder farmers' local practices enhance the use of agroforestry technologies in the eastern highlands of Uganda. This information will help develop and promote agroforestry practices that are acceptable to farmers. The study employed a case study approach, collecting data from 12 smallholder farmers over four months. The results indicate that smallholder farmers use local practices to enhance tree seedling survival, optimize space, and shorten the waiting time for tree-related benefits. Although some of their practices may not align with the desired outcome of farm productivity, further validation is needed to understand how they can be integrated into mainstream agroforestry research and development

Built environment and the evolution of the “15-minute city”: A 25-year longitudinal study of 200 Swedish cities

This article aims to examine how key features of the built environment have influenced the development of the 15-minute city in Swedish cities. Using longitudinal register data geocoded at a 100-meter level and encompassing the entire population and workplaces, we track the 200 largest Swedish cities over a 25-year period (1992–2017). The 15-minute city is operationalized as the proportion of the population in each city that can access a range of non-work urban social functions within a short distance from home. The study uses various multivariate modeling techniques, including fixed effect models, to measure the effects of changes in the built environment. We thus address significant research gaps by investigating the dynamic nature of the 15-minute city concept, conducting comparisons within and across multiple cities, and considering the influence of the built environment, particularly in smaller cities. Results show that population size has less significance than expected, and that smaller cities can achieve certain criteria of the 15-minute city. However, increasing population density and promoting mixed land use clearly contribute to fostering the 15-minute city. Moreover, cities that to a larger extent were developed before mass motorization tend to exhibit a greater degree of 15-minute city characteristics. The results highlight the importance of making long-term, thoughtful, strategic decisions in urban planning efforts aimed at transforming cities into 15-minute cities.

The Sympatric Coexistence Mechanism: A Case Study of Two Penahia Species in the Beibu Gulf, South China Sea.

The study of trophic relationships among closely related species plays an important role in deepening our understanding of the resource utilization characteristics, differentiation patterns, and population dynamics of co-occurring species in the same habitat. This research uses two congeneric fish species, Pennahia pawak and Pennahia anea, as examples. Based on a stomach content analysis and a carbon-nitrogen stable isotope analysis, a comparative analysis of their feeding habits and trophic niches is conducted. Additionally, a spatial niche analysis is employed to explore the coexistence and competitive mechanisms between these two closely related fish species. The results show that specialized feeding habits mitigate intraspecific competition as the population densities increase. The carbon and nitrogen stable isotope analysis reveals variations in the feeding habits and trophic levels with body length, indicating adaptive shifts in prey selection. Despite similar food resources, niche differentiation arises due to differences in dominant prey, facilitating coexistence. Differences in spatial niche further contribute to niche separation and coexistence. In resource-limited environments, species such as Pennahia utilize trophic and spatial niche differentiation to collectively exploit resources and achieve coexistence, with implications for fishery management favoring Pennahia resource occupancy capabilities.

Innovative porous mortar filters: wastewater purification for clean water.

Water scarcity is a major global challenge that affects both developed and developing countries, with Indonesia serving as a prime example. Indonesia's archipelagic nature, combined with its dense population, exacerbates the severity of water scarcity. The increased population density in these areas raises the demand for water resources, putting a strain on the available supply. The purpose of this research was to create porous mortar filters (PMFs) with different ratios (1:4, 1:5, and 1:6) by incorporating 10, 15, and 20% adsorbent material by weight of fine aggregate. The research was carried out in three stages: determining PMF properties, preparing synthetic wastewater, and assessing treatment effectiveness. Various PMF compositions consistently achieved notable success, with reductions in total dissolved solids and turbidity exceeding 25 and 75%, respectively. The PMF performed admirably in eliminating bacterial concentrations, achieving a 100% removal rate, and was critical in efficiently reducing metals, with compositions achieving over 80% reduction for manganese (Mn) and 38% reduction for iron (Fe). PMF emerges as a practical solution as a cost-effective and simple water treatment technology, particularly suitable for areas with limited technological infrastructure and resources, providing accessible water treatment for communities facing challenges in this regard.

Unpacking the journey to property crime in Changchun, China

AbstractJourney to crime describes the spatial patterns of offenders from their residential area to the crime location. When compared to other research topics regarding urban crime, there is still a lack of research on journey to crime, especially in China, as a result of which the behavioural motivation of offenders cannot be comprehensively examined. Four typical types of crimes committed against property (pickpocketing, robbery, theft and burglary) were investigated in the Nanguan District of Changchun from 2010 to 2016. The results showed significant effects of the demographic characteristics of offenders and spatiotemporal factors on the journey to crime. In terms of the place of household registration, offenders from the central urban districts of Changchun tend to commit short‐distance local robbery, whereas those from the suburban counties tend to commit long‐distance non‐local crimes. With increasing population density, the proportion of local plunders increases directly. This study aims to encourage urban managers to rethink the governance of floating populations, and assist police in strengthening social security.