首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 734 毫秒
1.
A stratified random sample of kilometre squares in Great Britain was visited and completely mapped using four areal themes (agriculture and semi-natural vegetation, forestry, physiography and buildings and communications). The maps were digitised and the attribute information recorded to produce an electronic database. Information was summarised by square and then bootstrap re-sampling techniques were used to produce national estimates with statistical confidence intervals. The results for 1998 showed the terrestrial Broad Habitats had a range in extent covering two orders of magnitude from Montane (49000ha) to Improved Grassland (5482000ha). Just under half of Britain is covered by agricultural Broad Habitats, about 12% by woodland and just under 10% by Urban Habitats. The remaining quarter of the land area is covered by semi-natural Broad Habitats. By revisiting the same sample of squares previously visited in 1990, changes in the quantity and quality of the Broad Habitats have been determined. Significant increases in area have occurred in the Broadleaved, Mixed and Yew Woodland and Built Up and Gardens. The largest areal reduction was in Acid Grassland although that was in part balanced by a gain in Fen, Marsh and Swamp. The most significant ecological loss was in the area of Calcareous Grassland. The consequences of having different sample sizes for the different years are discussed.  相似文献   

2.
3.
Estimates of terrestrial Broad Habitat cover for Wales from the Countryside Survey 2000 stratified sample field mapping programme in Britain are compared with the findings of a full census field mapping project, the Habitat Survey of Wales. The Countryside Survey sampling regime comprised a stratified random sample of 1 km squares [corrected] covering <0.5% of the land surface. Comparative assessment indicates that although few of the sample-derived estimates for individual Broad Habitats are within 30% of the full census survey results, relative extents accord with data from the complete census survey for all Broad Habitats apart from Arable & Horticultural. The accuracy of this estimate is improved when the national boundary of Wales is taken into account in the sample stratification scheme. It is suggested that cultural land-use differences between countries render cropland habitat extent less predictable from physical environmental parameters than semi-natural habitat extent. It is also shown that the precision of sample-derived cover estimates is influenced by habitat pattern: the error term associated with habitats of broadly equal extent is greater for those with the most clumped distributions.  相似文献   

4.
Local authorities in Great Britain have had the powers to acquire, declare and manage statutory Local Nature Reserves since 1949; these powers were extended to Northern Ireland in 1985. As of March 1997, there are some 564 Local Nature Reserves in England, three in Northern Ireland, 24 in Scotland and 38 in Wales. Local Nature Reserves are important for biodiversity and nature conservation at a local level and can have a special role for local schools. The overall situation in respect of Local Nature Reserves has been recently reviewed by the Urban Forum of the UK Man and the Biosphere Committee. This review will add impetus and purpose to the wide variety of programmesand projects involving Local Nature Reserves. It will add emphasis to their potential not only for nature conservation and environmental education but also for community development.  相似文献   

5.
Biodiversity planners increasingly recognise the need for delivering action on a ‘wider countryside’, rather than on a purely site‐centred, basis. Ecological processes often take place at the ‘landscape scale’ and are not sufficiently accommodated within reserves, and a failure to reflect this in biodiversity planning has been one of the contributors to species and habitat decline. However, there are generally few powers to enforce compliance with spatial rural land‐use strategies, and biodiversity plans at the landscape scale must rely heavily on incentives, advice and goodwill. Not surprisingly, this results in a substantial gap between policy and implementation. One way of analysing the causes of, and potential solutions to, implementation failure is to examine the barriers to plan uptake. This paper addresses barriers to biodiversity action in three case‐study areas in terms of ‘force fields’, depicting the nature and strength of negative and positive influences on land managers and conservation staff. It is concluded that a clearer understanding of the nature of ‘barriers’ can lead to improved targeting on potential ‘bridges’ to a better future.  相似文献   

6.
Rare and threatened habitats in Europe must be restored and enhanced in accordance with the European Union's Habitats and Species Directive. In the United Kingdom, conservation and expansion objectives for species and habitats are outlined in the Species Action Plans and Habitat Action Plans. Site identification for these measures has to date been ad hoc without consideration of either the existing "stock" of the natural resource or the ability of the surrounding land use to deliver the enhancement (enlargement) of a given habitat. Using a Geographical Information System, we outline a targeting system for creating new woodland in association with existing ancient woodland in the Chiltern Hills Area of Outstanding Natural Beauty. The aim was to create woodland blocks of at least 100 ha, as being of the most benefit to biodiversity. We identified existing patches of woodland between 20 and 50 ha as cores for habitat expansion and classified land use in terms of its suitability and proximity to these core areas for tree planting to meet the targets of the statutory body. Our results suggest that the targeting method employed is a useful tool for habitat restoration.  相似文献   

7.
8.
Countryside strategies, particularly for nature conservation, are part of a growth in non‐statutory strategic planning. They are largely integrative, and set the context for, and are able to cover subjects normally beyond the scope of, statutory development plans. Specifically for nature conservation, this paper summarizes the limitations of policies in structure plans and reviews four countryside strategies to assess the extent to which they overcome these limitations. Whilst providing a renewed focus for nature conservation, such strategies lack information and guidance in assisting plan formulation, are not accountable, have problems in their adoptability and lack the resources for implementation.  相似文献   

9.
There have been no published performance evaluations of nongovernmental, voluntary habitat stewardship programs. The Operation Burrowing Owl (OBO) stewardship program, initiated in 1987, was evaluated for its effectiveness in conservation of grassland habitat during 1986–1993. The 108 OBO sites from 1987 to 88 and 98 randomly selected non-OBO sites that were grassland in 1986 in the Regina-Weyburn, Saskatchewan study area were classified by size and agricultural soil suitability. By 1993, 41 (38%) of the 108 OBO sites had been withdrawn from the program. The 1986 area of grassland was compared with grassland area calculated from digitized 1993 LANDSAT imagery. A correction for satellite inaccuracies was determined. Grassland retention in 1993 was significantly higher at OBO sites (66%) than at random sites (49%), demonstrating that the OBO voluntary program effectively conserved habitat. Also, grassland retention was significantly lower on sites with better agricultural soils, and for sites <12 ha in size. Site type (OBO or random), size and their interaction, followed by agricultural soil suitability, had the greatest effects on grassland retention. During an era of accelerated grassland loss, OBO strongly and positively (statistically significant) affected conservation of grassland sites most at risk: sites <12 ha in size and with good to excellent agricultural soils. This suggests that grassland conservation efforts focus on vulnerable sites (small size and/or good agricultural soils) to provide nesting habitat for burrowing owls. Our study demonstrates that a voluntary stewardship program can significantly increase conservation of habitat.  相似文献   

10.
An assessment of the biodiversity of soils was a component of the Countryside Survey 2000 (CS2000). This was the first integrated survey of soil biota and chemical properties at a national scale. A total of 1052 soil samples were collected across Great Britain during CS2000 and analysed for a range of soil microbial and invertebrate characteristics resulting in the production of a series of robust datasets. A principal objective was to use these datasets to investigate relationships between soil biota and environmental factors such as geographical location, vegetation, land use, land cover, soil type and pollutant levels as first stages in characterising the inherent biodiversity of British soils and investigating the potential of soil biodiversity as indicators of soil health at a regional or national scale. Preliminary results for culturable heterotrophic, invertebrate taxa, Acari, Collembola and Oribatid mites are presented here to illustrate the nature of the data collected and the patterns of soil biodiversity in relation to large-scale regional, vegetation and soil characteristics across the British countryside.  相似文献   

11.
This study examined the effects of agricultural runoff on the vegetation structure of Franklin Bog, a priority conservation area located in a rapidly developing region of northwestern Vermont. Forested and agricultural runoff from the mixed land use watershed created differential vegetation patterns in the wetland, including weedy species introductions. Concentrations of nitrogen and phosphorus were measured in the stream runoff from four forested subwatersheds and two agricultural subwatersheds. Nutrient concentrations were significantly higher for agricultural vs. forested runoff for all measured parameters. Nitrate and total phosphorus concentrations in agricultural runoff ranged from 0.62 to 1.35 mg L(-1) and 0.07 to 0.37 mg L(-1), respectively. Forested runoff values were less than 0.37 mg L(-1) nitrate and 0.09 mg L(-1) total phosphorus. Significantly higher proportions of weedy species occurred at impacted vs. reference sites (46 +/- 5% vs. 23 +/- 4%). Furthermore, significantly higher total percent vegetated cover occurred at impacted vs. reference sites (116 +/- 11% vs. 77 +/- 9%) suggesting nutrient induced plant growth. Of the nine frequently occurring species categorized as bog species, only one was found within impacted sites while all nine were found at the reference sites. This suggests that the wetland's distinctive native flora is being replaced by widespread, vigorous species enhanced by agricultural nonpoint pollution in the watershed of Franklin Bog. Protection of wetlands requires attention to conservation measures throughout the entire watershed.  相似文献   

12.
In the U.K., the Countryside Act of 1968 represented the first “updating” of the pioneering National Parks and Access to the Countryside Act of 1949. Through the archival material that survives for the Ministry of Agriculture and Nature Conservancy, the paper commemorates that first quarter-century of post-war adjustment to the needs of farming and wildlife conservation. It does so through a case study of the documented discussion, both inter-agency and within separate counsels, of whether agricultural improvement grants should be paid for land scheduled as Sites of Special Scientific Interest (SSSIs). The post-war assumptions of both parties were shattered by clashes over the SSSIs of Cavenham Heath (Suffolk) and Waddingham Common (Lincolnshire). Characterized as a “cold” war, there was a point beyond which antipathy served no one's interests. Fully aware of the options available to policy-makers, both parties recognized the Countryside Bill as an opportunity to obtain greater protection for SSSIs without prejudicing the larger notions of guardianship of the rural resource and the importance that continued to be given to the countryside as the farmer's “workshop”.  相似文献   

13.
The European Habitats Directive 92/43/EEC has defined the need for the conservation of habitats and species with the adoption of appropriate measures. Within the Natura 2000 ecological network of special areas of conservation, natural habitats will be monitored to ensure the maintenance or restoration of their composition, structure and extent. The European Space Agency's GlobWetland project has provided remotely sensed products for several Ramsar wetlands worldwide, such as detailed land cover-land use, water cycle and inundated vegetation maps. This paper presents the development and testing of an operational methodology for updating a wetland's habitat map using the GlobWetland products, and the evaluation of the extent to which GlobWetland products have contributed to the habitat map updating. The developed methodology incorporated both automated and analyst-supervised techniques to photo-interpret, delineate, refine, and evaluate the updated habitat polygons. The developed methodology was proven successful in its application to the wetland complex of the Axios-Loudias-Aliakmon delta (Greece). The resulting habitat map met the European and Greek national requirements. Results revealed that GlobWetland products were a valuable contribution, but source data (enhanced satellite images) were necessary to discriminate spectrally similar habitats. Finally, the developed methodology can be modified for original habitat mapping.  相似文献   

14.
Biodiversity offsets are increasingly being used for securing biodiversity conservation outcomes as part of sustainable economic development to compensate for the residual unavoidable impacts of projects. Two recent New Zealand examples of biodiversity offsets are reviewed—while both are positive for biodiversity conservation, the process by which they were developed and approved was based more on the precautionary principal than on any formal framework. Based on this review and the broader offset literature, an environmental framework for developing and approving biodiversity offsets, comprising six principles, is outlined: (1) biodiversity offsets should only be used as part of an hierarchy of actions that first seeks to avoid impacts and then minimizes the impacts that do occur; (2) a guarantee is provided that the offset proposed will occur; (3) biodiversity offsets are inappropriate for certain ecosystem (or habitat) types because of their rarity or the presence of threatened species within them; (4) offsets most often involve the creation of new habitat, but can include protection of existing habitat where there is currently no protection; (5) a clear currency is required that allows transparent quantification of values to be lost and gained in order to ensure ecological equivalency between cleared and offset areas; (6) offsets must take into account both the uncertainty involved in obtaining the desired outcome for the offset area and the time-lag that is involved in reaching that point.  相似文献   

15.
Biodiversity planners increasingly recognise the need for delivering action on a 'wider countryside', rather than on a purely site-centred, basis. Ecological processes often take place at the 'landscape scale' and are not sufficiently accommodated within reserves, and a failure to reflect this in biodiversity planning has been one of the contributors to species and habitat decline. However, there are generally few powers to enforce compliance with spatial rural land-use strategies, and biodiversity plans at the landscape scale must rely heavily on incentives, advice and goodwill. Not surprisingly, this results in a substantial gap between policy and implementation. One way of analysing the causes of, and potential solutions to, implementation failure is to examine the barriers to plan uptake. This paper addresses barriers to biodiversity action in three case-study areas in terms of 'force fields', depicting the nature and strength of negative and positive influences on land managers and conservation staff. It is concluded that a clearer understanding of the nature of 'barriers' can lead to improved targeting on potential 'bridges' to a better future.  相似文献   

16.
Three different systems of designating protected areas in a Mediterranean region in southeastern Spain were studied, referring to their effectiveness and efficiency for protecting both the breeding territories and the suitable habitat of a set of ten raptor species. Taking into consideration the varying degrees of endangerment of these species, a map of multispecies conservation values was also drawn up and superimposed on the three protected-area systems studied. In order to compare the levels of protection afforded by the three systems, we considered two indices that measured their relative effectiveness and efficiency. The effectiveness estimated the proportion of territories or optimal habitat protected by the networks while efficiency implicitly considered the area of each system (percentage of breeding territories or optimal habitat protected per 1% of land protected). Overall, our results showed that the most efficient system was that formed by the set of regional parks and reserves (17 protected breeding territories per 100 km2), although, given its small total area, it was by far the least effective (only protecting the 21% of the breeding territories of all species and 17% of the area of high conservation value). The systems formed by the Special Protection Areas (designated under the EU “Birds Directive”) and by the Special Conservation Areas (designated under the EU “Habitats Directive”) notably increased the percentages of protected territories of all species (61%) and area of high conservation value (57%), but their efficiency was not as high as expected in most cases. The overall level of protection was high for all species except for the Lesser Kestrel (Falco naumanni), an endangered falcon that inhabits pseudo-steppe and traditional agricultural habitats, which are clearly underrepresented in the protected-area network of the study region.  相似文献   

17.
Economic growth,biodiversity loss and conservation effort   总被引:6,自引:0,他引:6  
This paper investigates the relationship between economic growth, biodiversity loss and efforts to conserve biodiversity using a combination of panel and cross section data. If economic growth is a cause of biodiversity loss through habitat transformation and other means, then we would expect an inverse relationship. But if higher levels of income are associated with increasing real demand for biodiversity conservation, then investment to protect remaining diversity should grow and the rate of biodiversity loss should slow with growth. Initially, economic growth and biodiversity loss are examined within the framework of the environmental Kuznets hypothesis. Biodiversity is represented by predicted species richness, generated for tropical terrestrial biodiversity using a species-area relationship. The environmental Kuznets hypothesis is investigated with reference to comparison of fixed and random effects models to allow the relationship to vary for each country. It is concluded that an environmental Kuznets curve between income and rates of loss of habitat and species does not exist in this case. The role of conservation effort in addressing environmental problems is examined through state protection of land and the regulation of trade in endangered species, two important means of biodiversity conservation. This analysis shows that the extent of government environmental policy increases with economic development. We argue that, although the data are problematic, the implications of these models is that conservation effort can only ever result in a partial deceleration of biodiversity decline partly because protected areas serve multiple functions and are not necessarily designated to protect biodiversity. Nevertheless institutional and policy response components of the income biodiversity relationship are important but are not well captured through cross-country regression analysis.  相似文献   

18.
The need for enhanced environmental planning and management for highland aquatic resources is described and a rationale for integrated action planning is presented. Past action planning initiatives for biodiversity conservation and wetland management are reviewed. A reflective account is given of integrated action planning from five sites in China, India and Vietnam. Eight planning phases are described encompassing: stakeholder assessment and partner selection; rapport building and agreement on collaboration; integrated biodiversity, ecosystem services, livelihoods and policy assessment; problem analysis and target setting; strategic planning; planning and organisation of activities; coordinated implementation and monitoring; evaluation and revised target setting. The scope and targeting of actions are evaluated using the Driving forces, Pressures, State, Impacts and Responses framework and compatibility with biodiversity conservation and socio-economic development objectives are assessed. Criteria to evaluate the quality of planning processes are proposed. Principles for integrated action planning elaborated here should enable stakeholders to formulate plans to reconcile biodiversity conservation with the wise use of wetlands.  相似文献   

19.
Human-induced global climate change presents a unique and difficult challenge to the conservation of biodiversity. Despite increasing attention on global climate change, few studies have assessed the projected impacts of sea-level rise to threatened and endangered species. Therefore, we estimated the impacts of rising sea levels on the endangered Lower Keys marsh rabbit (Sylvilagus palustris hefneri) across its geographic distribution under scenarios of current conditions, low (0.3-m), medium (0.6-m), and high (0.9-m) sea-level rise. We also investigated the impacts of allowing vegetation to migrate upslope and not allowing migration and of two land-use planning decisions (protection and abandonment of human-dominated areas). Not surprisingly, under all simulations we found a general trend of decreasing total potential LKMR habitat with increasing sea-level rise. Not allowing migration and protecting human-dominated areas both tended to decrease potential LKMR habitat compared with allowing migration and abandoning human-dominated areas. In conclusion, conservation strategies at multiple scales need to be implemented in order to reduce the impact of global climate change on biodiversity and endangered species. At the regional level, managers must consider land-use planning needs that take into account the needs of both humans and biodiversity. Finally, at the local scale those agencies that are in charge of endangered species conservation and ecosystem management need to rethink static approaches to conservation or else stand by and watch ecosystems degrade and species go extinct. This can be accomplished by bioclimatic reserve systems where climatically underrepresented areas are included in conservation planning along with the standard concerns of threat, opportunity, connectivity, and viability.  相似文献   

20.
Field boundaries are man-made features found worldwide and their multiple functions in agricultural landscapes are now widely recognised. These landscape features have declined drastically in many developed countries as a result of agricultural intensification. In Great Britain, field boundaries are regarded as elements of particular significance in the countryside, both in term of extent and value, whether ecological, cultural, or aesthetic. The Countryside Surveys of Great Britain, a national ecological, surveillance programme initiated in the late 1970s, provides information about the change in extent and ecological condition of field boundaries. In this paper, we present the main results on field boundaries derived from the latest survey, Countryside Survey 2000. These include stock and change of boundaries for the 1990-1998 period as well as an update of the previously published 1984-1990 data. Special attention is given to the evolution of the length of hedges. Applicability of the Countryside Survey methodology to other monitoring programmes and further use of the data is discussed together with the potential ecological consequences of the changes described in the paper.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号