Policy Considerations for Small Towns

The impacts of population change on carbon emissions in China during 1978–2008

Considered a keystone species in the southeastern US coastal plain, gopher tortoises occupy a variety of upland habitat types. Although upland pine-dominated habitats have received much attention, few studies have examined tortoises in nearby coastal beach dune habitats. To examine the distribution and abundance of gopher tortoises in northeast Florida coastal habitats, comprehensive burrow surveys were conducted 3 times during the last 8 yrs on 2 separate gopher tortoise populations near St. Augustine, Florida. The objectives for these surveys were to 1) examine changes in population size and structure in representative upland and coastal dune habitats and 2) describe the response of gopher tortoises to land management practices (i.e., prescribed fire). Total burrow density within the upland population remained stable over the 3 surveys (0.68 burrows/ha in 2005, 0.66 burrows/ha in 2007, and 0.64 burrows/ha in 2011). Burrow densities in the burned areas of the upland habitat increased in areas that were burned at least once since the time of the first survey in 2005 but decreased in areas that were infrequently burned or remained unburned. Burrow density on the beach dunes, however, greatly increased between the most recent 2 surveys (3.63 burrows/ha in 2007 and 8.95 burrows/ha in 2011), possibly attributable to an increased use of a relatively confined habitat, or sampling biases by surveyors. Three different correction factor methods were used to determine gopher tortoise population estimates for each of the surveys, providing a range of estimates. The results of this study and the few others focused on coastal beach dunes suggest that this vulnerable, yet important, habitat should receive more attention because some of the highest gopher tortoise burrow densities have been observed there.

Marine species are facing an increasing number of stressors and some species once thought to be resilient to change are now threatened. It is important to understand how species populations have changed through time so that management can be adjusted accordingly, and so that achievable restoration goals can be set. However, many species lack population data at multidecadal or longer time scales. Using historical data from the 1970s, this study investigates how the dynamics of a New Zealand abalone (Haliotis iris), or pāua, population at Peraki Bay changed over a 45-year period. No commercial fishing of the population occurred prior to the initial survey and limited commercial catch has been reported between surveys. Repeat monitoring of the H. iris population at a 45-year interval indicates that a large change in population size and structure had occurred. Since 1976, there has been an 84% decrease in estimated population size. The remaining population is restricted to where juveniles were found in the original survey. These findings are consistent with conclusions, made from modelling in the 1970s, that the population seen in the 1970s was not stable and that a possible cause was temporal variability in population recruitment.

Rural human settlement is an important factor in the sustainable development of the rural economy and society, and improving rural human settlement is an important task for China’s rural revitalization strategy. Based on the human settlement framework, this study constructed a comprehensive evaluation index system to evaluate the rural human settlement by calculating the rural human settlement index (RHSI) in Tibet. The results showed that: (1) The natural subsystem is extremely vulnerable. In recent years, the anti-interference ability and natural restoration ability of the ecosystem have gradually increased. Changes in population size, structure, and scale have made the level of the human subsystem lower. From the perspective of drinking water, communication and housing, the human settlement level of the residential subsystem was gradually improved. The construction of rural infrastructure was increasingly improved, driving the level of the supporting subsystem to improve. Furthermore, income and livelihood diversity were the key to improving the social subsystem; (2) From the perspective of the comprehensive index, the level of rural human settlement in Tibet showed a trend of significant improvement; (3) In terms of the explanatory power, the explanatory power of the five subsystems were quite different. The basic dimensions (natural subsystem, human subsystem, residential subsystem) lagged behind the development of the dominant dimensions (supporting subsystem, social subsystem). There were inconsistencies and mismatches. The recommended measures involve strengthening the top-level design of the planning of rural human settlement in farming and pastoral areas, and improving and strengthening the construction of rural infrastructure to improve the responsiveness of rural human settlement in Tibet.

Over a 52-month period beginning in May 2004 and concluding in August/September 2008, and coinciding with the period over which tributyltin was banned as a ship anti-foulant globally, a population of the dogwhelk, Nucella lapillus on the south-eastern coast of England, was studied for changes in population size and structure, reproduction and feeding behaviour. During the study period, the size of the N. lapillus population grew from ~25 individuals to >500, i.e. a 20-fold increase, and recovery from imposex was total. Significant changes in feeding behaviour were also reported. For example, peaks in N. lapillus predation were recorded over the winter months, but as population size increased, this temporal seasonality was masked due to the growing numbers of juveniles feeding on smaller and smaller individuals of Mytilus galloprovincialis (as opposed to barnacles) as the study progressed. Similarly, with freedom from imposex, the numbers of failed drilling attempts declined and numbers of prey with more than one drill hole increased as the incidence of kleptoparasitism increased. Predated M. galloprovincialis were also increasingly attacked in the antero- and postero-dorsal quadrants of their shells as the study progressed. Contrary to expectations, only a slightly positive relationship between predator and prey sizes was recorded overall however, suggesting that beyond a shell height of ~13 mm, when the transition from barnacle to mussel feeding occurs, M. galloprovincialis individuals of virtually any size are preyed upon by N. lapillus.

This model has been designed to assist decision making in the Health Services by predicting the effects on a local population of proposed policy decisions. Policy decisions are considered to:Change the amount of certain resources available, e.g. manpower, hospital beds; or Alter the methods of using resources, e.g. changing the emphasis of health care to the community rather than the hospital; or Change the characteristics of illnesses, e.g. by vaccination or screening. The model predicts the incidence of morbidity and mortality in a specified population and the changes in resource use over a period of years. Thus it is possible to see the long term effects of changes in population size and structure alongside the effects of management decisions on the use of health resources.The model has been designed principally for research purposes but has been used in the context of a health services management game. The validity of the model's predictions have yet to be tested. It is hoped to run the model in parallel with management decision making in a single health district in order to test the model's validity and improve its predictive ability.

Signatures of past changes in population size have been detected in genome-wide variation in many species. However, the causes of such demographic changes and the extent to which they are shared across co-distributed species remain poorly understood. During Pleistocene glacial maxima, many temperate European species were confined to southern refugia. While vicariance and range expansion processes associated with glacial cycles have been widely documented, it is unclear whether refugial populations of co-distributed species have experienced shared histories of population size change. We analyse whole-genome sequence data to reconstruct and compare demographic histories during the Quaternary for Iberian refuge populations in a single ecological guild (seven species of chalcid parasitoid wasps associated with oak cynipid galls). For four of these species, we find support for large changes in effective population size (Ne ) through the Pleistocene that coincide with major climate events. However, there is little evidence that the timing, direction and magnitude of demographic change are shared across species, suggesting that demographic histories in this guild are largely idiosyncratic, even at the scale of a single glacial refugium.

For most regions of Central and Eastern Europe there has been a noticeable decline in population in recent years. The purpose of this article is to analyse the level of economic and social indicators as well as changes in population size between 2008 and 2019 in the regions of Central and Eastern Europe. In particular, the article attempts to answer the question of how the change in selected economic and social indicators impacts the change in population size. The answer to the above question will be provided with the use of the ratio analysis and thesoft model. The research results show that the two causes of changes in population size (natural causes and migrations) are significantly affected by a group of social indicators, even though—with regard to migration—the significance of economic indicators is increasing and the difference between the former and the latter is not substantial. Consequently, in response to the depopulation process, more attention should be paid to the social dimension of development. In other words, creating proper conditions for personal and professional activity may be more important than using financial instruments.

In this paper an adaptive differential evolution algorithm with dynamic changes of population size is presented. In proposed algorithm an adaptive selection of control parameters of the algorithm are introduced. Due to these parameters selection, the algorithm gives better results than differential evolution algorithm without this modification. Also, in presented algorithm dynamic changes of population size are introduced. This modification try to overcome limitations connected with premature convergence of the algorithm. Due to dynamic changes of population size, the algorithm can easier get out from local minimum. The proposed algorithm is used to train artificial neural networks. Results obtained are compared with those obtained using: adaptive differential evolution algorithm without dynamic changes of population size, method based on evolutionary algorithm, error back-propagation algorithm, and Levenberg-Marquardt algorithm.

Offshore wind energy development (OWED), while a key strategy for reducing carbon emissions, has potential negative effects to wildlife that should be examined to inform decision making and adaptive management as the industry expands. We present a conceptual framework to guide the long-term study of potential effects to birds and bats from OWED. This framework includes a focus on exposure and vulnerability as key determinants of risk. For birds and bats that are exposed to OWED, there are three main effects of interest that may impact survival and productivity: 1) collision mortality, 2) behavioral responses, including avoidance, displacement, and attraction, and 3) habitat-mediated effects to prey populations. If these OWED effects cause changes in survival and/or breeding success (e.g., fitness), they have the potential for population-level consequences, including changes in population size and structure. Understanding the influence of ecological drivers on exposure and effect parameters can help to disentangle the potential impacts of OWED from other stressors. We use this theoretical framework to summarize existing relevant knowledge and identify current priority research questions (n=22) for the eastern United States, where large-scale development of OWED is primarily in the planning and early construction phase. We also identify recommendations for study design and further prioritization of research topics.

Functional traits can drive plant responses to short- and long-term stressful conditions, with potential effects on species persistence in local habitats, changes in population size and structure, and potential species range shifts in changing environments. We investigated whether ecophysiological traits in a rare cycad vary along environmental gradients and with ontogeny to understand intra-specific resource-use variation (e.g. symbiotic nitrogen fixation, nitrogen- and water-use efficiency) and possible species adaptations for different environments. Environmental gradients were characterized with 14 soil and topographic variables. Nitrogen- and water-use efficiency improved with ontogeny (from seedling to juvenile and adult stages) but declined as soil fertility decreased with increasing elevation. Conversely, reliance on symbiotic nitrogen fixation increased with elevation and varied slightly with ontogeny. Improved water-use efficiency at lower elevation and nitrogen fixation at higher elevation may represent key functional strategies for maintaining the lower and upper altitudinal species range limits, especially in arid environments where stressful conditions are intensifying due to climatic and land-use changes. In addition to facilitation linked to the regeneration niche, improved resource-use efficiency linked to the adult niche may strongly influence cycad distribution and persistence in contemporary environments. A functional approach to conservation of rare or endangered plant species may be needed in order to target the most sensitive stages to changing environmental conditions and to better understand potential range shifts and adaptive responses to global land-use and climate changes.

For a Wright-Fisher model with mutation whose population size fluctuates stochastically from generation to generation, a heterozygosity effective population size is defined by means of the equilibrium average heterozygosity of the population. It is shown that this effective population size is equal to the harmonic mean of population size if and only if the stochastic changes of population size are uncorrelated. The effective population size is larger (resp. smaller) than the harmonic mean when the stochastic changes of population size are positively (resp. negatively) autocorrelated. These results and those obtained so far for other stochastic models with fluctuating population size suggest that the property that effective population sizes are always larger than the harmonic mean under the fluctuation of population size holds only for continuous time models such as diffusion and coalescent models, whereas effective population sizes can be equal to or smaller than the harmonic mean for discrete time models.

Investing in health to improve healthy life expectancy (HLE) is fundamental to create a demographic dividend. However, how dramatic population ageing affects HLE remains unknown. This study aims to quantify and project the major diseases and injuries attributed to changes in population size and age structure that contributed to substantial losses in HLE. Using data from 188 countries in the Global Burden of Disease Study 2021 and World Population Prospects 2024, we assessed the correlation between HLE and total dependency ratios. Furthermore, we decomposed the mortality and disability burden attributable to changes in population size as well as age structure for 22 disease and injury categories and then quantified the loss of HLE due to the attributable burden. Additionally, we projected the loss of HLE due to priority diseases in 2030, while considering the impact of population ageing. From 2010 to 2019, globally, the mortality and disability burden attributable to age structure caused 0.40 years and 0.71 years of HLE loss, while for population size, these two estimates were 1.18 years and 1.00 years. By 2030, the mortality and disability burden attributable to age structure may lead to 0.76 years and 0.89 years of HLE loss, while for population size, these two predictions will be 1.21 years and 1.17 years. Population size growth is a consistent and crucial contributor to HLE losses. Reaping the second demographic dividend requires eliminating the double burden of premature death caused by infectious and chronic diseases, whereas gaining the sustainable third demographic dividend requires investments in healthy and successful ageing.

We tested whether variation in heterozygosity could produce cyclic changes in population size in meadow voles (Microtus pennsylvanicus). For this to occur, three conditions must be met: (1) populations are more outbred (heterozygotic) at high than low population density, (2) heterozygotic voles are more aggressive than relatively inbred individuals, and (3) heterozygotic voles have lower reproductive fitness, though being superior at defending resources. We found no evidence that heterozygosity varied with population size or that reproductive success varied with heterozygosity. However, the former test was indirect and relatively weak. We directly measured aggression and heterozygosity of individual voles. Aggression was significantly related to heterozygosity: higher heterozygosity correlated with more aggression in males and less aggression in females. The proportion of variance in aggression that could be explained by heterozygosity was small. These results suggest that changes in population size of meadow voles could not be driven by systematic changes in heterozygosity with population size.

Surveys to monitor changes in population size over time are of interest for a variety of research questions and management goals. For example, population biologists require survey data collected over time to test hypotheses concerning the patterns and mechanisms of population regulation or to evaluate the effects on population size of interactions caused by competition and predation. Resource managers use changes in population size to (i) evaluate the effectiveness of management actions that are designed to increase or decrease numbers, (ii) monitor changes in indicator species, and (iii) quantify the effects of environmental change. Monitoring population size over time is particularly important to species conservation, where population decline is one key to identifying species that are at risk of extinction.