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 31 毫秒
1.
Factors shaping overall species richness and representation of endangered species of vascular flora and butterflies were determined in 48 nature reserves in Prague, Czech Republic. Total species richness of both groups, and the presence of endangered butterflies, reflect the present status of habitats, while that of endangered plants reflects habitat composition at the time of reserve establishment. Reserve area has a much stronger effect on the species richness of sessile plants than mobile butterflies which, especially endangered species, respond more positively to heterogeneity than to area. Both species richness and endangered species peak in reserves half covered with forest, likely because they harbor species of both woodland and non-woodland habitats, and edge specialists. Solely relying on area and disregarding habitat quality, or a failure to conserve small but high quality sites, may be counterproductive for conserving endangered plant and butterfly species. To conserve diversity of plants and butterflies current management practices, often aimed at maintaining large blocks of pre-selected plant communities, should change to include maintenance of fallows, edges and transient zones.  相似文献   

2.
The diversity patterns, the ecological structure and the typical species of the orthopteran assemblage in the Dadia reserve are investigated. The reserve was designed to protect the black vulture (Aegypius monachus) and other raptors. A total of 39 orthopteran species were found, including Paranocarodes chopardi, a pamphagid species with very restricted distribution. All species can be represented in a network of six complementary habitats, including open oak woodlands, agricultural fields separated with hedges, humid grasslands, as well as serpentine grasslands. The buffer zone of the reserve is far more important for Orthoptera conservation than the core areas, which host most of the black vulture nests. Management focusing on raptors is in general compatible with conservation of Orthoptera. We suggest the maintenance of forest openings in the buffer zone, the maintenance of forest heterogeneity, the enhancement of periodical livestock grazing, and the use of nine indicator species and Paranocarodes chopardi in the reserve monitoring program.  相似文献   

3.
In terms of managing biodiversity, a third of the land area of New Zealand is included in a conservation estate of national parks, reserves and sanctuaries. Administration of this large natural heritage asset is by 13 separate Department of Conservation (DOC) conservancies. A survey was conducted, across all conservancies, of DOC staff directly involved with the management and recovery of threatened New Zealand species. The aim of the survey was to gain an insight into how DOC staff regard the management tools available to them for the recovery of threatened species. The survey also assessed the perceived relevance of the threatened species recovery plans (TSRPs) currently in use by these staff. The results of the survey show that in general, the DOC staff consider that a lack of adequate funding, poor communication between conservancies and staff shortages have resulted in failure to achieve comprehensive management and recovery of threatened species. There was an expectation for TSRPs to comprehensively guide management and recovery actions but most staff concluded that TSRPs failed to meet this objective. It was identified that TSRPs need to be kept up-to-date and preferably in an electronic format accessible to all DOC staff throughout New Zealand. There was strong support for the establishment of a national approach for the recovery of threatened species. Concern was expressed that current resourcing only allowed recovery of a very small number of New Zealand’s threatened species with staff calling for secure funding for the duration of threatened species recovery programmes.  相似文献   

4.
Species specific levels of genetic diversity are necessary for the viability of populations. Erebia epiphron (Lepidoptera: Satyrinae) is a relic species in the Sudetan Mountains, Czech Republic. These populations represent a suitable study object to test the population genetic effects of large, small and introduced populations by means of allozyme electrophoresis. A large continuous and viable population (>100,000 individuals) shows a significantly higher genetic diversity than a small isolated and declining population (ca. 5000 individuals), which most probably was founded during the Little Ice Age in the 17th and 18th centuries and became isolated afterwards. In 1932 and 1933, 50 females were transferred from the large population to the Krkonose Mountains, where they established a viable and quickly expanding population. The number of transferred individuals was sufficient to transfer most of the allozyme diversity of the large natural population. Due to the higher elevation of the Krkonose in comparison to the native range, this allocation might safeguard the survival of the Czech race of E. epiphron even under conditions of global warming.  相似文献   

5.
We use data from the French national butterfly atlas to compare the potential of direct geographical and neighbourhood models to account for numbers of species and incidence of species in French départements. Direct geographical models use data on latitude, longitude and altitude, whereas neighbourhood models use information from adjacent areas. Both geographical models and neighbourhood models account for a large proportion of the variance in species richness (68-78%). However, neighbourhood models are more successful than models based solely on simple geographical variables. A large number of individual species distributions are accounted for by logistic and autologistic regression models (222 of 246 species, 90.2%). The autologistic models incorporate information on neighbouring areas. The exceptions are rare species, five of six of which occur in a single administrative unit only (2.4%), or virtually ubiquitous species found in >90% of units (7.3%). Autologistic models dominate logistic models in accounting for species incidences using stepwise logit regressions, neighbourhood variables appearing in 64.5% of successful species models (absent in 22.8%) and then always entering first. A simple neighbourhood (distance-unweighted) measure (C2) dominates more models (89 of 246 species, 36.2%) than a distance-weighted neighbourhood measure (C1; 77 of 246 species, 31.3%). The models are here demonstrated to be potentially valuable for identifying under-recording and losses from regional extinction and for filling gaps in recording. The findings reveal substantial, apparent, losses of species in western and northern France as well as substantial discrepancies (differences) in numbers of species, for some administrative units (départements) and for both post-1970 and total records, compared with numbers predicted to occur. We use two distinct approaches on total species and individual species to provide comparative estimates of the numbers of species expected within spatial units and we present the number of additional units in which species are expected to occur. The probabilities for these species in French départements are available on Web site: http://www.brookes.ac.uk/schools/bms/research/data/ecology/butterfly.html.  相似文献   

6.
The use of monitoring, by means of transect counts, to assess the effect of management on the butterflies of a nature reserve is described. Trends in numbers at Monks Wood National Nature Reserve over a seven-year period are compared with the trends calculated from the combined data from a number of other sites in eastern England. Departures in the Monks Wood data from wider trends are shown. These departures are shown to be related to management of the rides and fields of the reserve.  相似文献   

7.
This paper describes successes and complications in eutrophication abatement in the Naardermeer nature reserve, The Netherlands. Restoration of this lake started in 1985. The main measure was the reduction of external nutrient load by the supply of phosphate-free water. Water quality and aquatic vegetation were monitored and the usefulness of a modelling approach in designation of management programs was investigated. The monitoring showed that for the first 4 years, recovery was retarded, possibly because of phosphorus release from the lake-bed sediments. After 10 years, turbidity was reduced and characteristic vegetation with Najas marina and Characeae species had re-established in large parts of the lake. Due to spatial heterogeneity it appeared necessary to dredge the lake-bed sediments locally. The model predicted most changes in aquatic vegetation correctly, indicating its predictive value. However, to predict restoration perspectives for rare species, expert judgement still remains necessary. Suggestions are made for selection of successful management measures depending on the conditions of lake ecosystems.  相似文献   

8.
Initiatives that establish species rarity as an indicator of conservation priority might be biased if they disregard important evolutionary and adaptive processes taking place in lower diversity communities and ecotones. Conservation policies regarding the Atlantic forest strongly emphasize the core formation (i.e. the rainforest stricto sensu) rather than the marginal habitats (e.g. restingas, swamps, and high altitude campos) and species that are rare/endemic. To discuss this issue I revisit a hypothesis I have forwarded in 2002 that postulates that plant colonization of habitats marginal to the Atlantic rain forests of the State of Rio de Janeiro was largely related to terrestrial nurse plants that originally, in the rainforest habitat, were canopy plants such as epiphytes or hemi-epiphytes. Adaptations to water and nutrient restrictions, typical of life in the canopy, granted success to such plants upon migration to sandy, swampy or rocky substrates in neighbouring areas. Many such species, then, behaved as nurse plants and favoured colonization of these more extreme habitats by a number of other rainforest species. I now review recent evidence that corroborate this hypothesis, while examining the nature of such nurse plants. In all marginal habitats, nurse plants are often highly abundant locally and have high ecophysiological vigour, while both widespread and endemic species are found among them. Thus, nursing effect, local abundance, and ecophysiological performance are not related to species geographic distribution or to their spectrum of habitat preference. Paradoxically, several abundant nurse plant species have low Darwinian fitness. These studies provoke two reflections. First, the Atlantic forest sensu lato, i.e. the core formation plus the peripheral ones, should be treated collectively as a biodiversity hotspot, rather than the core rainforest formation alone. Second, widespread or common species play important functional roles in such marginal habitats and, despite their ubiquity, ecologically they might be less fit than rare/endemic ones at the local level due, for instance, to current constraints to sexual reproduction. Thus, they should also be targeted as conservation priorities.  相似文献   

9.
The patterns of plant species diversity in herbaceous vegetation subjected to various human activities were studied in most of the landscape elements in a rural area of Chiba, central Japan. Twenty-eight transects were sampled in four types of human management-regime (cultivation, trampling, mowing, and abandonment) and were grouped into seven vegetation types using TWINSPAN and DCA analyses. The DCA axis 1 arranged all the transects into a successional order along which biomass and the degree of succession increased. Accumulated number of species increased in a stepwise pattern along the DCA axis 1, in which the dominant plant life-forms were replaced from annuals, to perennials and perennials/tree-saplings depending on different management regimes. The unique species which were confined to a certain management regime, were identified in each site. It is suggested that the coexistence of various successional communities under different human management regimes enhance regional species diversity through maintaining these unique species. Among four types of management regime, mowing sites (especially traditional verge meadows) had most abundant unique, rare species specially adapted to regular cutting. It is suggested that maintaining such traditional mown sites is important to conserve the unique biodiversity of the studied area.  相似文献   

10.
The conservation of biological diversity requires an integrated approach covering the ecological demands of a multitude of species. Integration may be achieved by focusing on a careful selection of target species, which is rare in practice. Calcareous grasslands offer a case in point. Although they harbour a high diversity of both plant and insect species, in management the emphasis is placed on the flora. This results in an underestimation of, notably, the importance of structural heterogeneity in the vegetation. As an apparent consequence, conservation management in the Netherlands has been much more successful for the flora than for butterflies. In contrast, Germany shows promising efforts to integrate both plant and animal species in conservation management and landscape planning. The main constraints for a successfully integrated conservation management presently consist of a limited availability and exchange of information, and an insufficient organisation of research and management at an international level.  相似文献   

11.
Effective biodiversity conservation requires an analysis of the existing reserve system. In temperate and boreal regions, plant diversity has a strong positive association with soil pH. Consequently, in order to protect plant diversity effectively, a relatively large proportion of protected areas should be on high pH soils. Since biodiversity data are never complete for all taxa, biodiversity indicators, e.g., threatened species, should be used. We studied soil pH distributions in protected areas in Northern Europe and tested whether soil pH requirement differs between threatened and non-threatened bryophyte and vascular plant species. As result, the proportion of high pH soils in protected areas was significantly greater than the proportion of these soils in general. This ensures that a large regional pool of plant species preferring high pH soils is relatively well protected. Threatened and non-threatened species in Northern Europe did not differ in their soil pH requirements, but threatened species required a narrower soil pH range than non-threatened species. Consequently, threatened species diversity can be used for indicating overall plant diversity.  相似文献   

12.
Although data quality and weighting decisions impact the outputs of reserve selection algorithms, these factors have not been closely studied. We examine these methodological issues in the use of reserve selection algorithms by comparing: (1) quality of input data and (2) use of different weighting methods for prioritizing among species. In 2003, the government of Madagascar, a global biodiversity hotspot, committed to tripling the size of its protected area network to protect 10% of the country’s total land area. We apply the Zonation reserve selection algorithm to distribution data for 52 lemur species to identify priority areas for the expansion of Madagascar’s reserve network. We assess the similarity of the areas selected, as well as the proportions of lemur ranges protected in the resulting areas when different forms of input data were used: extent of occurrence versus refined extent of occurrence. Low overlap between the areas selected suggests that refined extent of occurrence data are highly desirable, and to best protect lemur species, we recommend refining extent of occurrence ranges using habitat and altitude limitations. Reserve areas were also selected for protection based on three different species weighting schemes, resulting in marked variation in proportional representation of species among the IUCN Red List of Threatened Species extinction risk categories. This result demonstrates that assignment of species weights influences whether a reserve network prioritizes maximizing overall species protection or maximizing protection of the most threatened species.  相似文献   

13.
Systems for ranking species can aid governmental agencies and other groups in determining conservation priorities. However, current systems rarely account for the effects that uncertainty, i.e. incomplete knowledge of a species or biological variability within a species, may have on determining a species' rank. We tested whether three methods of incorporating uncertainty into a ranking system produced changes in conservation priorities. Our analysis focused on 55 species of mammals native to Indiana, USA. Uncertainty was incorporated into a ranking system by permitting survey respondents to assign probabilities to each category of a question. The ranks between species priority scores for methods with and without uncertainty were highly correlated. All methods gave results comparable to the qualitative ranking system currently in use. However, some species of conservation concern received substantially different ranks across methods. We recommend using a variety of scoring methods to produce a robust assessment of a species' conservation status.  相似文献   

14.
The potential as indicators of species richness were investigated for 178 species belonging to six ecologically defined species groups (epiphytic bryophytes on nutrient-rich bark, epiphytic macrolichens on nutrient rich bark, pendant lichens on conifer trees, bryophytes on siliceous rocks, bryophytes on dead conifer wood, and polypore fungi on dead conifer wood), using species data from 0.25 ha plots from three different coniferous forest areas (ca. 200 ha each). A species was defined as a potential indicator species for a species group within a study area if its distribution was statistically significantly nested within the species-plot matrix ranked according to species richness, and if the plot frequency of the species was less than 25%.Only two species were identified as potential indicators within all three areas and on average ≈80% of the potential indicator species were lost from one area to another. The results indicate that inconsistency between areas in the species’ frequency distributions and their position in nested hierarchies may strongly reduce the general predictive power of indicator species of species richness, even if significantly nested patterns are found at the community level. We suggest that indicators related to amount and quality of habitats may be an alternative to lists of indicator species of species richness.  相似文献   

15.
16.
17.
The problems existing in design of buffer zones are analyzed, and a procedure for designing the buffer zone of reserves is proposed. The Analytic Hierarchy Process (AHP) is applied to design the width of buffer zone. The different importance of influences in different sections around the reserve leads to different widths of buffer zone being designated around the reserve. The method is illustrated by a case study, designing the buffer zone for the Yancheng Biosphere Reserve, China.  相似文献   

18.
Butterflies and burnet moths are a suitable model species group with which to analyse the general decline of invertebrate biodiversity over the last few decades. In this study, we analysed which ecological groups of butterflies and burnet moths are most affected and how the recent modifications of the landscape have influenced them. Therefore, we studied the species composition of seven calcareous grassland remnants in south-western Germany in 1972 and 2001. We observed a strong change in the community composition and a severe decline in species richness. In general, the incidence of the autochthonous non-ubiquitous species declined by more than 50%, whereas ubiquitous species showed no significant difference in numbers during this period. Especially affected by the decline were those species which need structured habitats, those which are poor dispersers, species which need habitat sizes of 16 ha and more, monophagous species, K strategists and Red Data Book species. Most probably, either habitat outside the reserves is affecting dynamics within the reserves or loss of habitat outside the protected areas has reduced the overall area and connectivity of habitat for some species, increasing extinction rates and reducing colonisation rates in metapopulations. We conclude that these negative trends can only be stopped or even reversed if the landscape structure is made less hostile for species with conservation interest.  相似文献   

19.
A great number of wheat genetic resources are distributed in China, and more than 40,000 accessions have been conserved in the National Crop Gene Bank. The diversity of these wheat genetic resources was evaluated for the following fields: distribution areas and growth environments; collection status; genetic diversity in agronomic characters, grain quality, resistance to diseases, pests and environmental stresses, and crossability. According to the results of diversity evaluation, some collections with desirable characters have been obtained.  相似文献   

20.
The kakapo (Strigops habroptilus) is a large, flightless, nocturnal parrot, endemic to New Zealand. It is critically endangered, with a world population of ca. 62 individuals and a male-biased adult sex ratio. The species has a polygynous “lek” mating system and adult males typically weigh 30-40% more than females. The kakapo is subject to intensive conservation efforts, including the provision of supplementary food to wild birds to encourage successful nesting. There is mounting evidence that, in polygynous species with large variance of male reproductive success, females in better condition may maximise their fitness by producing more offspring of the larger, more costly sex to be reared. We used data on the sex ratio of progeny of female kakapo that had or had not received supplementary food, to test the hypothesis that supplementary feeding might cause a male-biased offspring sex ratio. There was a significant excess of males in the clutches of females provided with supplementary food, suggesting that changes need to be made to the feeding regime to increase recruitment of females. This is an example of applying evolutionary theory to a practical conservation problem.  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