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1.
In the highlands of New Guinea, the development of agriculture as an indigenous innovation during the Early Holocene is considered to have resulted in rapid loss of forest cover, a decrease in forest biodiversity and increased land degradation over thousands of years. But how important is human activity in shaping the diversity of vegetation communities over millennial time-scales? An evaluation of the change in biodiversity of forest habitats through the Late Glacial transition to the present in five palaeoecological sites from highland valleys, where intensive agriculture is practised today, is presented. A detailed analysis of the longest and most continuous record from Papua New Guinea is also presented using available biodiversity indices (palynological richness and biodiversity indicator taxa) as a means of identifying changes in diversity. The analysis shows that the collapse of key forest habitats in the highland valleys is evident during the Mid–Late Holocene. These changes are best explained by the adoption of new land management practices and altered disturbance regimes associated with agricultural activity, though climate change may also play a role. The implications of these findings for ecosystem conservation and sustainability of agriculture in New Guinea are discussed.  相似文献   

2.
Measures of biodiversity encompass variation along several dimensions such as species richness (SR), phylogenetic diversity (PD) and functional/trait diversity (TD). At the global scale, it is widely recognized that SR and PD are strongly correlated, but the extent to which either tends to capture variation in TD is unclear. Here, we assess relationships among PD, SR and TD for a number of traits both across clades and regional assemblages of mammals. We also contrast results using two different measures of TD, trait variance and a new measure we refer to as trait bin filling (the number of orders of magnitude of variation that contain at least one species). When TD is defined as trait variance, PD is a much stronger correlate of TD than SR across clades, consistent with hypotheses about the conservation value of PD. However, when TD is defined as bin filling, PD and SR show similar correlations with TD across clades and space. We also investigate potential losses of SR, PD and TD if species that are currently threatened were to go extinct, and find that threatened PD is often a similar predictor of threatened TD as SR.  相似文献   

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Phylogenetic diversity (PD) represents the evolutionary history of a species assemblage and is a valuable measure of biodiversity because it captures not only species richness but potentially also genetic and functional diversity. Preserving PD could be critical for maintaining the functional integrity of the world's ecosystems, and species extinction will have a large impact on ecosystems in areas where the ecosystem cost per species extinction is high. Here, we show that impacts from global extinctions are linked to spatial location. Using a phylogeny of all mammals, we compare regional losses of PD against a model of random extinction. At regional scales, losses differ dramatically: several biodiversity hotspots in southern Asia and Amazonia will lose an unexpectedly large proportion of PD. Global analyses may therefore underestimate the impacts of extinction on ecosystem processes and function because they occur at finer spatial scales within the context of natural biogeography.  相似文献   

5.
Limited by the availability of data, conservation planners must use surrogates for biodiversity when selecting conservation areas. Although several methods have been proposed for selecting surrogates, no clear set of species attributes have been described that allow for the efficient a priori selection of surrogate groups. We used a database of 1449 species in two regions of the United States to (1) examine the consistency in the performance of simple taxonomic-based surrogates of biodiversity and (2) test five hypotheses proposed to explain surrogate performance. First, we compared the ability of sites selected to protect members of seven surrogate groups to protect non-surrogate species in the north-western United States and in the Middle-Atlantic region of the eastern United States. Then, in a separate analysis, we tested whether surrogate performance could be explained by (1) taxonomic diversity; (2) nested species distributions; (3) hotspots of biodiversity; (4) species range sizes; (5) environmental diversity. Our first analysis revealed little consistency in the performance of surrogates in the two different study regions. For example, butterflies provided protection for 76% of all other species in the north-western United States but only 56% of all other species in the eastern United States. Our second analysis revealed only weak associations between species characteristics and surrogate performance. Furthermore, these associations proved inadequate for selecting successful surrogates across study regions. Overall, our results suggest that in lieu of searching for optimal surrogate groups, research efforts will be better spent by developing alternative methods for assessing conservation value in areas where data on species distributions are limited.  相似文献   

6.
Agricultural intensification is best considered as the level of human appropriation of terrestrial net primary production. The global value is set to increase from 30%, increasing pressures on biodiversity. The pressures can be classified in terms of spatial scale, i.e. land cover, landscape management and crop management. Different lowland agricultural landscapes in Great Britain show differences among these pressures when habitat diversity and nutrient surplus are used as indicators. Eutrophication of plants was correlated to N surplus, and species richness of plants correlated with broad habitat diversity. Bird species diversity only correlated with habitat diversity when the diversity of different agricultural habitats was taken into account. The pressures of agricultural change may be reduced by minimizing loss of large habitats, minimizing permanent loss of agricultural land, maintaining habitat diversity in agricultural landscapes in order to provide ecosystem services, and minimizing pollution from nutrients and pesticides from the crops themselves. While these pressures could potentially be quantified using an internationally consistent set of indicators, their impacts would need to be assessed using a much larger number of locally applicable biodiversity indicators.  相似文献   

7.
An objective of biodiversity conservation activities is to minimize the exposure of biodiversity features to threatening processes and to ensure, as far as possible, that biodiversity persists in the landscape. We discuss how issues of vulnerability and persistence can and should be addressed at all stages of the conservation planning and implementation process. Procedures for estimating the likelihood of persistence and for measuring degrees of vulnerability at different spatial and temporal scales using subjective assessments, rules of thumb and analytical and simulation models are reviewed. The application of information on vulnerability and persistence to conservation planning and management is discussed under the headings of natural dynamics, replication of protection, levels of representation, source and sink population structures, refuges and critical resources, reserve design, habitat fragmentation and levels of management.  相似文献   

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Deadwood-associated species are increasingly targeted in forest biodiversity conservation. In order to improve structural biodiversity indicators and sustainable management guidelines, we need to elucidate ecological and anthropogenic drivers of saproxylic diversity. Herein we aim to disentangle the effects of local habitat attributes which presumably drive saproxylic beetle communities in temperate lowland deciduous forests. We collected data on saproxylic beetles in 104 oak and 49 beech stands in seven French lowland forests and used deadwood, microhabitat and stand features (large trees, openness) as predictor variables to describe local forest conditions. Deadwood diversity and stand openness were consistent key habitat features for species richness and composition in deciduous forests. Large downed deadwood volume was a significant predictor of beetle species richness in oak forests only. In addition, the density of cavity- and fungus-bearing trees had weak but significant effects. We recommend that forest managers favor the local diversification of deadwood types, especially the number of combinations of deadwood positions and tree species, the retention of large downed deadwood and microhabitat-bearing trees in order to maximize the saproxylic beetle diversity at the stand scale in deciduous forests. To improve our understanding of deadwood-biodiversity relationships, further research should be based on targeted surveys on species-microhabitat relationships and should investigate the role of landscape-scale deadwood resources and of historical gaps in continuity of key features availability at the local scale.  相似文献   

10.
The tentacles of deep-sea holothurians show a wide range of morphological diversity. The present paper examines gross tentacle morphology in surface deposit feeding holothurians from a range of bathymetric depths. Species studied included the elasipods: Oneirophanta mutabilis, Psychropotes longicauda and Benthogone rosea and the aspidochirotids: Paroriza prouhoi, Pseudostichopus sp., Bathyplotes natans and Paroriza pallens. The sympatric abyssal species Oneirophanta mutabilis, Psychropotes longicauda and Pseudostichopus sp. show subtle differences in diet and the structure and filling patterns of the gut that suggest differences in feeding strategies which may represent one mechanism to overcome competition for food resources in an environment where nutrient resources are considered to be, at least periodically, limiting. Interspecific differences in tentacle functional morphology and digestive strategies, which reflects taxonomic diversity could be explained in terms of Sanders'; Stability–Time Hypothesis. Since different tentacle types will turn over sediments to different extents, their impact on sedimentary communities will be enormous so that high diversity in meiofaunal communities may be explained most simply by Dayton and Hessler's Biological Disturbance Hypothesis.  相似文献   

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Summary

The oil-shale bings of West Lothian, Scotland, are a group of post-industrial waste sites, unique in Britain and Western Europe. The industrial exploitation of oil-bearing rocks has created a habitat with its own distinctive flora and fauna. The floral diversity of individual sites has been documented as species lists in several studies. A comprehensive list of more than 350 plant species, with supplementary information on animal species, was compiled from an extensive literature review of these studies. From these data it was possible to determine the extent of species variation within and between bings, identify locally and nationally rare species, and thus to determine the importance of the oil-shale bing habitat at a local and national scale. The results will go some way to allay concerns about the loss of local biodiversity, generally throughout the country side, due to changes in agricultural practices and increased urbanisation. Findings from the bings and evidence from other types of derelict land suggest that species are not lost, they have moved to new habitats.  相似文献   

13.
Identifying local extinctions is integral to estimating species richness and geographic range changes and informing extinction risk assessments. However, the species occurrence records underpinning these estimates are frequently compromised by a lack of recorded species absences making it impossible to distinguish between local extinction and lack of survey effort—for a rigorously compiled database of European and Asian Galliformes, approximately 40% of half-degree cells contain records from before but not after 1980. We investigate the distribution of these cells, finding differences between the Palaearctic (forests, low mean human influence index (HII), outside protected areas (PAs)) and Indo-Malaya (grassland, high mean HII, outside PAs). Such cells also occur more in less peaceful countries. We show that different interpretations of these cells can lead to large over/under-estimations of species richness and extent of occurrences, potentially misleading prioritization and extinction risk assessment schemes. To avoid mistakes, local extinctions inferred from sightings records need to account for the history of survey effort in a locality.  相似文献   

14.
The achievements of initiatives to strengthen biodiversity conservation in developing countries may be difficult to assess, since most countries have no system for monitoring biodiversity. This paper describes a simple and cost-effective, field-based biodiversity monitoring system developed specifically for areas where specialist staff is lacking. We discuss the preliminary lessons learned from protected areas in the Philippines. Whilst the monitoring system aims to identify trends in biodiversity and its uses so as to guide management action, it also promotes the participation of local people in the management, stimulates discussions about conservation amongst stakeholders and builds the capacity of park staff and communities in management skills. In addition, it seeks to provide people with direction regarding the aims of protected areas, and reinforces the consolidation of existing livelihoods through strengthening community-based resource management systems. The field methods are: (1) standardised recording of routine observations, (2) fixed point photographing, (3) line transect survey, and (4) focus group discussion. Both bio-physical and socio-economic data are used and given equal importance. The system can be sustained using locally available resources. The approach is useful in countries embarking on shared management of park resources with local communities, where rural people depend on use of natural ecosystems, and where the economic resources for park management are limited. We hope this paper will encourage other countries to develop their own biodiversity monitoring system, letting its development become a means for capacity building whilst at the same time supporting the creation of ownership.  相似文献   

15.
Although the maintenance of diversity of living systems is critical for ecosystem functioning, the accelerating pace of global change is threatening its preservation. Standardized methods for biodiversity assessment and monitoring are needed. Species diversity is one of the most widely adopted metrics for assessing patterns and processes of biodiversity, at both ecological and biogeographic scales. However, those perspectives differ because of the types of data that can be feasibly collected, resulting in differences in the questions that can be addressed. Despite a theoretical consensus on diversity metrics, standardized methods for its measurement are lacking, especially at the scales needed to monitor biodiversity for conservation and management purposes. We review the conceptual framework for species diversity, examine common metrics, and explore their use for biodiversity conservation and management. Key differences in diversity measures at ecological and biogeographic scales are the completeness of species lists and the ability to include information on species abundances. We analyse the major pitfalls and problems with quantitative measurement of species diversity, look at the use of weighting measures by phylogenetic distance, discuss potential solutions and propose a research agenda to solve the major existing problems.  相似文献   

16.
Kelantan State, claimed to be one of the poorest states in Malaysia, has forest lands, nature reserves and other protected natural areas which are under increasing threat from a variety of human activities. At the same time, the State government lacks financial resources and skilled manpower to manage the protected forest lands adequately. The present strategies to manage protected forest areas are inadequate to overcome these constraints. Alternative strategies are needed to conserve Kelantan's forest biodiversity. Furthermore, conservation efforts will not be effective without the active cooperation and participation of people living in and near the forest areas. To achieve this, it is essential that the people share the benefits and responsibilities of forest resource management with the state government.A proposal to involve the local people in an integrated action plan is discussed in this paper. It aims to find options of protecting forest land encroachment in the State with an ultimate goal of increasing the capacity of the poor to carry out activities on a sustained basis. It is hoped that the proposed project will help the State government to improve economic status as well as environmental awareness and reduced dependence on forest lands.Much of the forest lands in Kelantan are threatened by encroachment from the people who live around the forest areas. This encroachment is not only the result of poverty and shortage of land, but is also due to the unclear forest boundaries. People also do not understand the significance of forest biodiversity. It is important therefore that the local people are encouraged not to encroach into the forest areas. There has to be support from the top in order to sustain integration efforts. Both the State and the central government agencies must be a part of the planning and implementation process. The challenge becomes one of integrating the needs of the local people with development priorities of the government. In practical terms, this paper hopes to arrive at a workable methodology rather than be a purely scientific exercise which can serve as a model to the other states experiencing similar problems.Presented at the Asean Seminar on Management and Conservation of Biodiversity, 29 November–1 December 1993, Kuala Lumpur.  相似文献   

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Biodiversity patterns of the woodland-steppe ecotone in southeastern Inner Mongolia were investigated. Controlled by climatic factors, the plant species diversity of the woodland-steppe ecotone is moderate as compared with the adjacent woodland and steppe communities. From woodland through woodland-grassland and woodland-steppe to steppe, about 2/3 species were replaced at each boundary; only seven herb species were detected to be distributed in all four vegetation zones. Landscape classification based on landform, climate, and vegetation shows that landform condition is most critical to landscape diversity in the studied area. The most fragmented landform in the woodland zone does not necessarily lead to low plant species diversity. However, similar understory species in different woodland types lead to continuous woodland vegetation and, hence, high species richness. High fragmentation in the woodland-steppe zone and discontinuous distribution of woodlands might be a driving factor for lower species richness. Reconstruction of the Holocene climatic changes and vegetation development demonstrates that the highest plant species diversity occurred in the ecotone from 4500 to 2500 14C yr BP at different sites, while the woodland zone extended much farther northwestward. When woodlands retreated from the current ecotone with climatic drying, the fragmentation of woodlands in the current ecotone led to plant species loss.  相似文献   

20.
海南岛生物多样性保护优先区评价与系统保护规划   总被引:4,自引:0,他引:4  
选择海南岛140个濒危物种为指示物种,在物种栖息地评价的基础上,利用系统保护规划工具MARXAN模型进行迭代运算,提出了海南岛生物多样性保护优先区域,并对保护优先区进行评价.结果表明:海南岛保护优先区面积5383.7km2,占海南岛陆地面积的15.6%,集中分布于鹦哥岭、尖峰岭、五指山等林区和北部湿地;在保护优先区中,11个I级指示物种栖息地的保护比例均超过各自栖息地总面积的65%.通过对保护优先区与现有自然保护区的空缺分析,建议扩充尖峰岭保护区群、鹦哥岭-黎母山保护区群、五指山-吊罗山保护区群;新建抱龙林场-林鼻岭-福万岭保护体系;在海南岛北部建立以水源保护为主,同时兼顾珍稀物种保护的水源地保护带.  相似文献   

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