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Human Population Growth (human + population_growth)
Selected AbstractsRange-wide patterns of greater sage-grouse persistenceDIVERSITY AND DISTRIBUTIONS, Issue 6 2008Cameron L. Aldridge ABSTRACT Aim, Greater sage-grouse (Centrocercus urophasianus), a shrub-steppe obligate species of western North America, currently occupies only half its historical range. Here we examine how broad-scale, long-term trends in landscape condition have affected range contraction. Location, Sagebrush biome of the western USA. Methods, Logistic regression was used to assess persistence and extirpation of greater sage-grouse range based on landscape conditions measured by human population (density and population change), vegetation (percentage of sagebrush habitat), roads (density of and distance to roads), agriculture (cropland, farmland and cattle density), climate (number of severe and extreme droughts) and range periphery. Model predictions were used to identify areas where future extirpations can be expected, while also explaining possible causes of past extirpations. Results, Greater sage-grouse persistence and extirpation were significantly related to sagebrush habitat, cultivated cropland, human population density in 1950, prevalence of severe droughts and historical range periphery. Extirpation of sage-grouse was most likely in areas having at least four persons per square kilometre in 1950, 25% cultivated cropland in 2002 or the presence of three or more severe droughts per decade. In contrast, persistence of sage-grouse was expected when at least 30 km from historical range edge and in habitats containing at least 25% sagebrush cover within 30 km. Extirpation was most often explained (35%) by the combined effects of peripherality (within 30 km of range edge) and lack of sagebrush cover (less than 25% within 30 km). Based on patterns of prior extirpation and model predictions, we predict that 29% of remaining range may be at risk. Main Conclusions, Spatial patterns in greater sage-grouse range contraction can be explained by widely available landscape variables that describe patterns of remaining sagebrush habitat and loss due to cultivation, climatic trends, human population growth and peripherality of populations. However, future range loss may relate less to historical mechanisms and more to recent changes in land use and habitat condition, including energy developments and invasions by non-native species such as cheatgrass (Bromus tectorum) and West Nile virus. In conjunction with local measures of population performance, landscape-scale predictions of future range loss may be useful for prioritizing management and protection. Our results suggest that initial conservation efforts should focus on maintaining large expanses of sagebrush habitat, enhancing quality of existing habitats, and increasing habitat connectivity. [source] Land use change and the dependence of national priority species on protected areasGLOBAL CHANGE BIOLOGY, Issue 9 2008SARAH F. JACKSON Abstract The establishment and maintenance of a system of protected areas is central to regional and global strategies for the conservation of biodiversity. The current global trend towards human population growth and widespread environmental degradation means that such areas are becoming increasingly isolated, fragmented habitat islands. In regions in which this process is well advanced, a high proportion of species are thus predicted to have become restricted to protected areas. Here, using uniquely detailed datasets for Britain, a region with close to the global level of percentage coverage by statutory protected areas, we determine the extent of restriction of species of conservation concern to these areas. On the basis of currently known distributions, more than a half of such species are highly dependent on protected areas for their continued persistence, occurring either entirely or largely within their bounds. Such coverage is of particular importance for those species with narrower distributions, and therefore, under the greatest threats, underlining the vital importance of adequately resourcing, maintaining, and developing protected areas to prevent these species from being lost. [source] Modelling the long-term sustainability of indigenous hunting in Manu National Park, Peru: landscape-scale management implications for AmazoniaJOURNAL OF APPLIED ECOLOGY, Issue 4 2009Taal Levi Summary 1. ,Widespread hunting throughout Amazonia threatens the persistence of large primates and other vertebrates. Most studies have used models of limited validity and restricted spatial and temporal scales to assess the sustainability. 2. ,We use human-demographic, game-harvest and game-census data to parameterize a spatially explicit hunting model. We explore how population growth and spread, hunting technology and effort, and source,sink dynamics impact the density of black spider monkeys Ateles chamek over time and space in the rainforests of south-eastern Peru. 3. ,In all scenarios, spider monkey populations, which are vulnerable to hunting, persist in high numbers in much of Manu National Park over the next 50 years. Nonetheless, shotguns cause much more depletion than traditional bow hunting by Matsigenka (Machiguenga) indigenous people. 4. ,Maintenance of the current indigenous lifestyle (dispersed settlements, bow hunting) is unlikely to deplete spider monkeys and, by extension, other fauna, despite rapid human population growth. This helps explain why large, pre-Colombian human populations did not drive large primates to extinction. When guns are used, however, spider monkeys quickly become depleted around even small settlements, with depletion eventually reversing the short-term harvest advantage provided by shotgun hunting. Thus, our models show that when guns are used, limits on settlement numbers can reduce total depletion. 5. ,Synthesis and applications. Our framework lets us visualize the future effects of hunting, population growth, hunting technology and settlement spread in tropical forests. In Manu Park, the continued prohibition of firearms is important for ensuring long-term hunting sustainability. A complementary policy is to negotiate limits on new settlements in return for development aid in existing settlements. The advantage of the latter approach is that settlement numbers are more easily monitored than is hunting effort or technology. Similar policies could help to reduce landscape-scale depletion of prey species in human-occupied reserves and protected areas throughout the Amazon. [source] An ecological study of the relationship between two living fossils in Malawi: the Mulanje Tiger Moth (Callioratis grandis) and the Mulanje Cycad (Encephalartos gratus)AFRICAN JOURNAL OF ECOLOGY, Issue 2 2010Julian Bayliss Abstract The Mulanje tiger moth (Callioratis grandis) has recently been discovered feeding solely on the Mulanje Cycad, Encephalartos gratus. In its type locality Encephalartos gratus is severely threatened through habitat destruction and human population growth. As a result the first detailed demographic survey of Encephalartos gratus on Mount Mulanje was undertaken with particular emphasis on the relationship between E. gratus and Callioratis grandis. What is unusual about C. grandis is that the males exhibit lekking behaviour, for which aposematism may be a prerequisite. Cycads were surveyed in a systematic manner. Both the biotic and abiotic parameters were recorded from 532 wild Encephalartos gratus. Results showed the morphological range of measurements differed from that of previously published literature on this species. Results also showed that the incidence of Callioratis larval damage was related to the maturity of the wild cycads , moth damage was greater on more mature plants. Approximately 50% of surveyed cycads showed evidence of Callioratis moth damage, however, there was no apparent preference from the moth to select either male or female cycads as food plants for the larvae. In some cases there was severe damage to cycad fronds, but this did not seem to affect the production of reproductive cones or even the survival of individual cycads. Résumé On a découvert récemment que le papillon du Mulanje (Callioratis grandis) ne se nourrit que sur le cycadale Mulanje Encephalartos gratus. Dans son milieu type, Encephalartos gratus est gravement menacé dans la nature à cause de la destruction de l'habitat et de la croissance de la population humaine. Par conséquent, la première étude démographique détaillée d'Encephalartos gratus réalisée sur le mont Mulanje fut entreprise en insistant particulièrement sur la relation entre Encephalartos gratus et Callioratis grandis. Ce qui est inhabituel chez C. grandis, c'est que les mâles présentent un comportement territorial (lek). Les cycadales ont été systématiquement surveillées. On a enregistré les paramètres biotiques et abiotiques pour 532 Encephalartos gratus poussant dans la nature. Les résultats ont montré que l'amplitude des mesures morphologiques différait de ce que la littérature existante décrit sur cette espèce. Ils ont aussi montré que l'incidence des dommages causés par les larves de Callioratisétait liée à la maturité des cycadales sauvages , les dégâts causés par les papillons étaient plus graves sur les plants plus matures. Environ 50% des cycadales suivis montraient des traces de dommages causés par ce papillon, mais il n'y avait pas de preuve qui aurait pu montrer que le papillon sélectionnait des cycadales mâles ou femelles pour en nourrir ses larves. Dans certains cas, il y avait des dégâts sérieux dans les feuilles de cycadales; cependant, cela ne semblait pas affecter la production de cônes reproducteurs, pas plus que la survie des individus. [source] Psychology of Promoting Environmentalism: Psychological Contributions toAchieving an Ecologically Sustainable Future for HumanityJOURNAL OF SOCIAL ISSUES, Issue 3 2000Stuart Oskamp The most serious long-term threat facing the world is the danger that human actions are producing irreversible, harmful changes to the environmental conditions that support life on Earth. If this problem is not overcome, there may be no viable world for our descendants to inhabit. Because this threat is caused by human population growth, overconsumption, and lack of resource conservation, social scientists have a vital role in helping our world escape ecological disaster and approach a sustainable level of impact on the environment,one that can be maintained indefinitely. Enormous changes to human lifestyles and cultural practices may be required to reach this goal. This article discusses major obstacles to this goal, describes a variety of motivational approaches toward reaching it, and proposes that we should view the achievement of sustainable living patterns as a superordinate goal,a war against the common enemy of an uninhabitable world. [source] The effect of development interventions on the use of indigenous range management strategies in the Borana Lowlands in EthiopiaLAND DEGRADATION AND DEVELOPMENT, Issue 4 2008S. Homann Abstract In the last three decades, the Borana rangelands of Southern Ethiopia have been deteriorating due to unsustainable utilization. This paper analyses the changes in indigenous range management among the Borana pastoralists and the role of development interventions. The fieldwork was carried out during 2000,2002, following a severe drought. Two locations, Dida Hara and Web, that once were part of a large grazing system with seasonally distinct herd movements, experienced differences in development interventions. Indigenous range management strategies and pastoralists' current use of key strategies before and after the last drought were compared based on pastoralists' information about land-use change collected through participatory appraisals, land-use mapping, and household surveys. Priorities for future interventions were discussed in multi-stakeholder workshops. Water development in rainy season grazing areas such as Dida Hara has resulted in year-round grazing and expansion of permanent encampments. This has affected the traditional dry-season areas like Web because it interrupted the organization of rangeland management. Herd mobility became less applicable and traditional land-use classifications have lost their function in range management. The introduction of government-imposed administration disturbed the indigenous institutional networks and negotiation procedures for controlled herd movements. Aggravated by human population growth, this reinforces a higher and more permanent grazing pressure, leading to the deterioration of rangelands. Despite the disturbance of pastoralists' range management practices considerable technical and management capabilities prevail. Innovative development approaches should integrate indigeneous knowledge-based (IK) strategies and formal legislation, but this requires strong external support and official recognition from the Ethiopian Government. Copyright © 2007 John Wiley & Sons, Ltd. [source] Use of wild and cultivated foods by chimpanzees at Bossou, Republic of Guinea: feeding dynamics in a human-influenced environmentAMERICAN JOURNAL OF PRIMATOLOGY, Issue 8 2009Kimberley J. Hockings Abstract Increased human population growth and more conversions of natural habitat to agricultural land have resulted in greater proximity between humans and nonhuman primate species. Consequent increases in resource competition including crop-raiding are a by-product of both natural resources becoming less available and the nutritional benefits of cultivated foods becoming more known to the nonhuman primates. Chimpanzees at Bossou in the Republic of Guinea, West Africa, consume 17 different types of cultivated foods that are grown extensively throughout their small, fragmented home range. Direct observations of feeding behavior conducted over an 18-month period revealed that during specific months crops account for up to one quarter of chimpanzee feeding time, with higher overall crop-raiding levels throughout the periods of wild fruit scarcity. Some cultivated foods, especially sugar fruits, are mostly fallback foods, whereas others, such as rice pith (Oryza sp.) and maize (Zea mays), are consumed according to their availability even when wild foods are abundant. These findings highlight the importance of both crop choice by farmers and a thorough understanding of the ecology of resident primate species when establishing land management techniques for alleviating human,primate conflict. Am. J. Primatol. 71:636,646, 2009. © 2009 Wiley-Liss, Inc. [source] Bioengineering nitrogen acquisition in rice: can novel initiatives in rice genomics and physiology contribute to global food security?BIOESSAYS, Issue 6 2004Dev T. Britto Rice is the most important crop species on earth, providing staple food for 70% of the world's human population. Over the past four decades, successes in classical breeding, fertilization, pest control, irrigation and expansion of arable land have massively increased global rice production, enabling crop scientists and farmers to stave off anticipated famines. If current projections for human population growth are correct, however, present rice yields will be insufficient within a few years. Rice yields will have to increase by an estimated 60% in the next 30 years, or global food security will be in danger. The classical methods of previous green revolutions alone will probably not be able to meet this challenge, without being coupled to recombinant DNA technology. Here, we focus on the promise of these modern technologies in the area of nitrogen acquisition in rice, recognizing that nitrogen deficiency compromises the realization of rice yield potential in the field more than any other single factor. We summarize rice-specific advances in four key areas of research: (1) nitrogen fixation, (2) primary nitrogen acquisition, (3) manipulations of internal nitrogen metabolism, and (4) interactions between nitrogen and photosynthesis. We develop a model for future plant breeding possibilities, pointing out the importance of coming to terms with the complex interactions among the physiological components under manipulation, in the context of ensuring proper targeting of intellectual and financial resources in this crucial area of research. BioEssays 26:683,692, 2004. © 2004 Wiley Periodicals, Inc. [source] | ||||||||||