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 0 毫秒
1.
Fir forests (Abies, Pinaceae) are dominant in temperate regions of North America; however, they have experienced high degradation rates that can threaten their long-term continuity. This study aimed to identify the priority areas for the conservation of the genus Abies in North America. First, we modeled the species distribution of the 17 native species through ecological niche modeling, considering 21 environmental variables. Then, we defined the priority areas through multi-criteria analysis, considering the species richness, geographic rareness, irreplaceability, habitat degradation, and risk extinction. We also built six scenarios, giving more priority to each criterion. Finally, we identified the proportion of the extent of the priority areas covered by protected areas. Elevation, precipitation seasonality, and winter precipitation influenced the distribution of most of the Abies species. When considering equal weights to each criterion, the priority areas summed up 6% of the total extent covered by the Abies species in North America. Most priority areas were located on the West Coast of the United States, the Eastern Sierra Madre, Southern Sierra Madre, Sierras of Chiapas and Central America, and the Trans-Mexican Volcanic Belt ecoregions. In these ecoregions, the Abies species are restricted to small areas facing high degradation levels. Only 16% of the area covered by the Abies species in North America is protected, mainly under restrictive schemes such as National Parks and Wilderness Areas. The priority areas identified could be the basis for establishing or enlarging protected areas. The preservation of the genus Abies could also maintain other ecological features and processes such as biodiversity, forest resources, and environmental services.  相似文献   

2.
In order to emphasize the importance of vegetation mapping for nature conservation purposes a case study in Terceira island (Azores) is presented, in which the importance of the natural vegetation of the eastern slope of Santa Bárbara volcano (which is part of the Site of Community Importance of Santa Bárbara–Pico Alto) is evaluated through the elaboration of its vegetation map. Fourteen (14) different natural vegetation types were identified: grasslands (1 type), peat bogs (2 types), scrubs (2), forests (5), successional vegetation (3) and vegetation of rocky slopes (1). All communities are protected under the Habitat and Species Directive (EC/92/43) and most of them are endemic to the Azores Islands. This fact, together with the significant number of Azorean endemic taxa (18), Macaronesian endemic taxa (5) and species protected under the Habitat and Species Directive (7), gives this area an important conservation value that justifies future protection actions. Vegetation mapping is an important tool for the characterization, evaluation and implementation of managing plans of natural areas of the Azores islands. The use of a floristic-based classification, supported by multivariate analysis and structural data, is an efficient methodology for the construction of these maps. The data collected comprise an important set of information about the distribution and abundance of natural vegetation types and endemic and rare species. This information was not available until now and is indispensable for the elaboration of management plans of Special Zones for Conservation that will be part of the NATURA 2000 network.  相似文献   

3.
We tested the surrogate value of butterflies, red-listed butterflies and grasshoppers for each other in terms of diversity patterns congruence and complementarity at a site in the NATURA 2000 network. Grammos Mountain is proposed as a new Prime Butterfly Area for Greece: it supports a total of 56 grasshopper species and 112 butterfly species, 24 of which are of European conservation concern (SPEC) and two of Prime Butterflies Area Project. We found a strong congruence in the species richness patterns of SPEC butterflies, butterflies and grasshoppers, because three common ecological factors influenced them: number of flower heads, altitude, and cover of low trees or bushes (Redundancy Analysis, CANOCO). Each complementarity network maintained quite well the species richness of the other two target groups (<18% average species loss). SPEC butterflies were the best surrogate group overall and therefore we propose that they should be monitored on a permanent basis.  相似文献   

4.
We analyse and report a synthesis of a long-term project leading to the creation of a database of habitats of conservation interest in Tuscany (Italy). All available floristic and vegetation literature from 1960 to date and relating to the Tuscan territory, and all terrestrial and inland water (non-marine) Habitats of European Community Interest as listed in Annex I of the EU Habitats Directive present in Tuscany have been identified and taken into account. A total of 2,691 sites were attributed to 82 different conservation interest habitat types and were geo-localised and uploaded to the database. For each habitat site, threat and pressure factors are indicated and a quick expert-based assessment made on the basis of three parameters: rarity, vulnerability and a quality estimate. For the analysis, all database information was referred to a vectorial 10 × 10 km grid. The territorial distribution of habitats is discussed with respect to: the level of information available, the numbers of reports and the habitat-type concentration. The major threats and pressures affecting these Tuscan habitats are highlighted and discussed. Vegetation dynamics proved to be the most important natural/seminatural threat. Another important threat is invasion by/competition with other organisms, mainly invasive alien species. Among anthropic threats, the management of riparian and aquatic vegetation together with water management all strongly affect many habitat types with links to wetlands. Infrastructures, particularly those connected with tourism and recreation, are an important threat factor especially in coastal areas. Some positive effects of certain anthropic pressures are also illustrated. Lastly, some actions to improve habitat knowledge, evaluation and conservation are suggested.  相似文献   

5.
Freshwater biodiversity is globally threatened and while most conservation efforts are focussed on natural and larger freshwater systems such as rivers and lakes, in many lowland agricultural landscapes artificial water bodies including ditches may be equally important as habitats for freshwater species. Ditches occur across the agricultural landscape but in particular, those associated with coastal and floodplain grazing marsh, have high conservation value. The importance of this habitat for rare and threatened species afforded priority status under the UK Biodiversity Action Plan is explored. The characteristics of ditches that have high conservation value are described and a set of targets against which such ditches can be assessed are presented. An analysis of the current condition of Sites of Special Scientific Interest (SSSI) for the wider coastal and floodplain grazing marsh habitat demonstrates the range of pressures affecting these sites and highlights that alongside generic freshwater issues such as eutrophication and non-native species, these sites have a unique set of pressures associated with their ongoing management and the vulnerable location of many sites at the coast. Wider conservation strategies for freshwater biodiversity in lowland landscapes across Europe need to factor in the different management requirements of artificial habitats such as ditches alongside more ambitious restoration projects for natural waterbodies. In low lying coastal areas the threat of coastal squeeze for many important grazing marshes will require a strategic approach to allow upstream migration of important biodiversity.  相似文献   

6.
The authors propose a statistical model for evaluating the Beginning of the Main Pollen Season (BMPS) of Urticaceae (cf. Parietaria) in Genoa (Italy). For eight consecutive years (1981–1988) the mean daily concentrations of this pollen grain were studied in relation to the two meteorological factors which are most significant in triggering the beginning of maximal pollination, namely, mean daily air temperature and rainfall. From a multiple-regression statistical analysis, a formula has been extrapolated, which, one the basis of these meteorological data for the month of January, can be used to predict the onset of the BMPS to within nine days.  相似文献   

7.
South East Asia is widely regarded as a centre of threatened biodiversity owing to extensive logging and forest conversion to agriculture. In particular, forests degraded by repeated rounds of intensive logging are viewed as having little conservation value and are afforded meagre protection from conversion to oil palm. Here, we determine the biological value of such heavily degraded forests by comparing leaf-litter ant communities in unlogged (natural) and twice-logged forests in Sabah, Borneo. We accounted for impacts of logging on habitat heterogeneity by comparing species richness and composition at four nested spatial scales, and examining how species richness was partitioned across the landscape in each habitat. We found that twice-logged forest had fewer species occurrences, lower species richness at small spatial scales and altered species composition compared with natural forests. However, over 80 per cent of species found in unlogged forest were detected within twice-logged forest. Moreover, greater species turnover among sites in twice-logged forest resulted in identical species richness between habitats at the largest spatial scale. While two intensive logging cycles have negative impacts on ant communities, these degraded forests clearly provide important habitat for numerous species and preventing their conversion to oil palm and other crops should be a conservation priority.  相似文献   

8.
Methods of identifying high conservation value forests (HCVFs) have been proposed in correspondence with the Russian national certification standard accredited by the Forest Stewardship Council (FCS). A landscape-typological approach has been assumed as a basis for HCVF identification. In fact, the HCVF concept is a modified interpretation of protective forest organization scheme. The methods can be applied in other Siberian regions.  相似文献   

9.
The long-term conservation of biodiversity and related ecosystems goods and services of the Autonomous Region of Madrid is jeopardized by the intensive resource-consuming development model followed by the region in the past few decades. This paper presents the aggregated results of the first integrated assessment of the protected areas of the Autonomous Region of Madrid (Spain) with the System for the Integrated Assessment of Protected Areas (SIAPA). Detailed results are also provided for individual protected areas as supplementary data. The assessment was done during 2009–2010, on ten protected areas differing in their sizes (from 2.5 to 52,796 ha), protection categories (seven categories) and types of ecosystems present. Comparison of results from both assessment models of the SIAPA (the Complete Model and the Simplified Model) is also presented. The results from the Complete Model show that eight out of the ten protected areas of the Autonomous Region of Madrid are currently ineffective. The poorest partial indexes overall were: “State of Conservation” and “Social and Economic Context”. The only indexes significantly correlated with the effectiveness of a protected area were: the “State of Conservation” (r = 0.851**) and the “Social Perception and Valuation” (r = 0.786**). Although not as relevant as was thought, “Management” and the other non-significant factors are likely to influence the effectiveness of protected areas as well. The results for the Simplified Model are slightly better than those for the Complete Model, although this is probably a specific result of this assessment. The two models of the SIAPA were very significantly correlated, although their aggregated results should not be compared directly.  相似文献   

10.
Salt marshes are wet environments at the transition between land and sea, which are inhabited by species that are adapted to stressing environmental factors, such as frequent tidal inundations and highly variable salinity. The rapid and global disappearance of these ecosystems results in the loss of those species that here have their typical habitat. In the lagoon of Venice, a programme for the protection of the surviving salt marshes was initiated by building dredge islands in the framework of more comprehensive restoration work. The ecological characterisation of these man-made habitats was studied through analysing the beetle fauna established on six dredge islands with different topographical traits. Beetle assemblages were evaluated by analysing species richness and abundance. The observed species were arranged in ecological groups and within sub-habitats, delimited according to the zonation of halophytes and ruderal vegetation. Both the composition and distribution of the beetle assemblages were strongly affected by the soil elevation, which determines the salinity gradient and the flooding rate. Hygrophilous and halobious taxa were dominant; however, many generalist taxa were present on some higher islands characterised by areas with a height greater than 60 cm above the mean sea level. Notably, these rarely submerged soils hosted some uncommon halophilous species, as well as thermophilous taxa typical of Mediterranean habitats that were not present on the surrounding mainland. Overall, although the dredge islands possessed some topographical traits that differed significantly from those of the natural salt marsh, they proved to host the biotic communities typical of these latter habitats, as well as other saline soil specialists.  相似文献   

11.
Tropical dry forests are more threatened, less protected and especially susceptible to deforestation. However, most deforestation research focuses on tropical rain forests. We analyzed spatial and temporal changes in land cover from 1972 through 2005 at Chatthin Wildlife Sanctuary (CWS), a tropical dry forest in Myanmar (Burma). CWS is one of the largest protected patches of tropical dry forest in Southeast Asia and supports over half the remaining wild population of the endangered Eld’s deer. Between 1973 and 2005, 62% of forest was lost at an annual rate of 1.86% in the area, while forest loss inside CWS was only 16% (0.45% annually). Based on trends found during our study period, dry forests outside CWS would not persist beyond 2019, while forests inside CWS would persist for at least another 100 years. Analysis of temporal deforestation patterns indicates the highest rate of loss occurred between 1992 and 2001. Conversion to agriculture, shifting agriculture, and flooding from a hydro-electric development were the main deforestation drivers. Fragmentation was also severe, halving the area of suitable Eld’s deer habitat between 1973 and 2001, and increasing its isolation. CWS protection efforts were effective in reducing deforestation rates, although deforestation effects extended up to 2 km into the sanctuary. Establishing new protected areas for dry forests and finding ways to mitigate human impacts on existing forests are both needed to protect remaining dry forests and the species they support.  相似文献   

12.
如何充分利用有限的资源更好地保护生物多样性一直都是保护地管理所追求的目标。整合保护对象、优化保护地的空间布局、有效识别国家公园优先保护区域是当前中国国家公园体制建设的主要任务。本研究以浙江丽水为例,采用生态模型评估了该区域关键生态系统服务(固碳释氧、水文调节、水资源、土壤保持)的空间分布格局,同时运用MaxEnt模型模拟了37种濒危物种适宜栖息地分布的空间格局。在此基础上,将关键生态系统服务和濒危物种作为保护对象,通过系统保护规划模型MARXAN,在0.4 km×0.4 km规划网格上计算丽水各规划单元的生态保护不可替代性指数,并结合当地管理需求,综合识别了国家公园优先保护区域。结果表明:2005—2015年间,研究区生态系统固碳量为0.05 kg C·m-2·a-1,释氧量为0.13 kg O2·m-2·a-1,水文调节量为83.25亿m3·a-1,水资源量为803 mm·a-1,土壤保持量为95.53 t·h...  相似文献   

13.
ABSTRACT

The aim of this paper is to present a joint vegetation data base and GIS application to produce a model to map the potential natural vegetation (PNV) of the Friuli-Venezia Giulia region (NE Italy) and to show how the map can be used to draw a biogeographic classification of the region. All the natural arboreal coenoses growing below the timber line, as well as the dwarf shrubs and prairies developing above this limit, were considered. Some cross sections, extracted from the potential vegetation map, were tested against transects of real vegetation distribution.  相似文献   

14.
In a context of scarce financial and human resources, the allocation of conservation efforts needs to be optimized. Our analysis attempts to draw conclusions on the integration of regional and local conservation assessments, specifically, with regard to the acquisition of fine‐scale data to complement the regional assessment. This study undertaken in Réunion Island (Indian Ocean) assessed how biodiversity surrogates targeted at a regional scale represented other biodiversity surrogates at a local scale. Biodiversity surrogates at both scales consisted of species, habitats and processes. Habitats and processes at regional scale were defined using a coarser scale of thematic resolution than at local scale. The surrogacy was tested in terms of incidental representation of local‐scale features in the regional assessments, and correlation of irreplaceability values between scales. Near‐minimum sets and irreplaceability values were generated using MARXAN software. Our results revealed that conservation targets for processes at local scale were never met incidentally, while threatened species and fragmented habitats were also usually under‐represented. More specifically, requiring only 12% of the local planning domain, the application of species as surrogates at regional scale was the least effective option at representing biodiversity features at local scale. In contrast, habitats at a coarse scale of thematic resolution achieved a significant proportion of conservation targets incidentally (67%) and their irreplaceability values were well correlated with the irreplaceability values of surrogates at local scale. The results highlighted that all three types of biodiversity surrogates are complementary for assessing overall biodiversity. Because of the cost of data acquisition, we recommended that the most efficient strategy to develop nested regional/local conservation plans is to apply habitats and processes at a coarse scale of thematic resolution at regional scale, and threatened species and degraded habitats at local scale, with their fine‐scale mapping limited to highly transformed areas.  相似文献   

15.
Global climate and land-use changes are the most significant causes of the current habitat loss and biodiversity crisis. Although there is information measuring these global changes, we lack a full understanding of how they impact community assemblies and species interactions across ecosystems. Herein, we assessed the potential distribution of eight key woody plant species associated with the habitat of the endangered Lilac-crowned Amazon (Amazon finschi) under global changes scenarios (2050′s and 2070′s), to answer the following questions: (1) how do predicted climate and land-use changes impact these species’ individual distributions and co-distribution patterns?; and (2) how effective is the existing Protected Area network for safeguarding the parrot species, the plant species, and their biological interactions? Our projections were consistent identifying the species that are most vulnerable to climate change. The distribution ranges of most of the species tended to decrease under future climates. These effects were strongly exacerbated when incorporating land-use changes into models. Even within existing protected areas, >50 % of the species’ remaining distribution and sites with the highest plant richness were predicted to be lost in the future under these combined scenarios. Currently, both individual species ranges and sites of highest richness of plants, shelter a high proportion (ca. 40 %) of the Lilac-crowned Amazon distribution. However, this spatial congruence could be reduced in the future, potentially disrupting the ecological associations among these taxa. We provide novel evidence for decision-makers to enhance conservation efforts to attain the long-term protection of this endangered Mexican endemic parrot and its habitat.  相似文献   

16.
Land use cover and the current ecological condition of the natural resources of a 71,300 ha area were assessed quantitatively and qualitatively. The Systematic Reconnaissance Flight (SRF) was used to achieve the above within severe time constraints set by the terms of reference for the project. North–south grid lines, spaced 1 and 2 km apart, were flown using a helicopter. Changes in land use classes along flight transects were documented using a Global Positioning System. The co-ordinates were transformed within a Geographic Information System into land cover values. The SRF with sampling intensities ranging from 5.13 to 9.89% yielded a difference of only 0.2% between the estimated cover of sugar cane compared to the known area under sugar cane. The other land cover classes were considered adequately quantified. The qualitative assessment shows the natural resources to be under severe strain, in particular within the riparian zone. Recommendations as to future agricultural expansion are made. The SRF was highly cost-effective in achieving the stated objectives of the project.  相似文献   

17.
The ecological and economic relevance of sweet chestnut (Castanea sativa Mill.) has long been related to its widespread geographical distribution and multipurpose product potential. In Central Italy, chestnut management represents a paradigmatic example of the potential conflict between landowner targets and biodiversity conservation: options for preserving stand-scale biodiversity are not fully considered as current management is based on monospecific, even-aged coppice stands and clearcutting on wide areas. Relationships between silvicultural treatment and floristic diversity of chestnut coppices are here investigated focusing the attention on rotation length and on the role of thinning. Seven coppice stands were selected in such a way to be of similar size (about 10 ha) and to cover a wide range of ages and a different number of thinnings. Plot sampling was performed across the stands and their floristic diversity was compared and analyzed by means of indicators in order to assess statistical relationships between floristic data and stand structural attributes. The achieved results suggest alternative suitable options for managing chestnut coppice stands in order to enhance biodiversity while maintaining wood production.  相似文献   

18.
It is generally assumed that the Neogene crocodylian fauna of Europe has been represented only by brevirostrine alligatoroid Diplocynodon and longirostrine false gharials ( Gavialosuchus and/or Tomistoma ), which became extinct prior to 6 Mya. Although several lines of evidence suggest that Crocodylus originated in Africa during the Miocene and then promptly dispersed to other continents, the occurrence of this genus in Europe has never been rigorously proven and the traditional palaeontological approach failed to identify a monophyletic group of fossil Crocodylus (simply leading to a proliferation of extinct taxa). The new remains reported here, from an endemic insular fauna from southern Italy, Late Messinian to earliest Pliocene in age (5–6 million years old), represent the youngest European crocodylian, and allow, for the first time in a phylogenetic context, an unambiguous demonstration that Crocodylus dispersed into Europe, possibly during the Tortonian. If the peculiar morphology of the medial maxillary edge is interpreted as evidence for a medial dorsal boss, the southern Italian Crocodylus could be related to C. checchiai from the late Neogene of Libya. The presence of this African immigrant in Europe confirms the role of climate change for faunal dispersal and island colonization.  © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 149 , 293–307.  相似文献   

19.
The optimal size of nature reserves has been debated for some time. Although edge and core habitats are often recognized, it is commonly assumed in theory and in studies of a particular habitat type that reserves or patches of different sizes have similar habitat structure. However, for older, highly fragmented landscapes it has been suggested that small areas are of conservation interest as high-quality remnants, whereas large areas are more degraded. We studied 49 randomly selected forest reserves in the size range 5–230 ha (typical for many highly fragmented landscapes) and 3653 sites of key habitat (unprotected deciduous broadleaf forest). Structures in forest that are generally correlated with value for biodiversity were measured, and reserve objectives were examined from declaration texts. Both the density of large trees and the density of dead wood (snags, logs) decreased with increasing reserve size. The mean size of identified key habitats was very small (1.6 ha). A botanical objective for establishment of reserves was more frequently used for smaller reserves. In contrast, cultural and especially recreational objectives were more commonly used when larger reserves were established, suggesting higher values for recreation in these reserves. For vascular plants, birds and beetles, a literature review indicated that small forest patches do not contain impoverished communities, but are often rich (per unit of area). Small reserves and key habitats have several disadvantages, but they are probably important components of reserve networks for biodiversity in highly fragmented landscapes.  相似文献   

20.
《Mycological Research》2006,110(6):705-712
Armillaria species are plant pathogens that cause Armillaria root rot and are known to cause mortality of mountain pines (Pinus mugo) in the Swiss National Park in the Central Alps. The identity of isolates and the spatially explicit population structure of the Armillaria species were investigated in a 3.3 km2 study area in the Swiss National Park. In total, 242 Armillaria isolates, 205 from wood samples and 37 from epiphytic rhizomorphs, were collected. Species were identified using haploid–diploid pairings and genets were determined using intraspecific somatic incompatibility tests. The population structure differed markedly among the Armillaria species. A. cepistipes and A. borealis mainly occurred as genets of small spatial extent (mean 0.2 ha, and 0.6 ha), whereas A. ostoyae formed significantly larger genets (mean 6.8 ha). The largest A. ostoyae genet extended over approx. 37 ha. Several disease centres associated with Heterobasidion annosum were found to be embedded within large Armillaria genets. The extension of large A. ostoyae genets suggests that forests that occupy the study area have developed in the presence of these Armillaria genets. The finding of large Armillaria genets supports the assumption that large genets occur in areas with cold climate and little precipitation.  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