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1.
Polar bear (Ursus maritimus) populations are predicted to be negatively affected by climate warming, but the timeframe and manner in which change to polar bear populations will occur remains unclear. Predictions incorporating climate change effects are necessary for proactive population management, the setting of optimal harvest quotas, and conservation status decisions. Such predictions are difficult to obtain from historic data directly because past and predicted environmental conditions differ substantially. Here, we explore how models can be used to predict polar bear population responses under climate change. We suggest the development of mechanistic models aimed at predicting reproduction and survival as a function of the environment. Such models can often be developed, parameterized, and tested under current environmental conditions. Model predictions for reproduction and survival under future conditions could then be input into demographic projection models to improve abundance predictions under climate change. We illustrate the approach using two examples. First, using an individual-based dynamic energy budget model, we estimate that 3-6% of adult males in Western Hudson Bay would die of starvation before the end of a 120 day summer fasting period but 28-48% would die if climate warming increases the fasting period to 180 days. Expected changes in survival are non-linear (sigmoid) as a function of fasting period length. Second, we use an encounter rate model to predict changes in female mating probability under sea ice area declines and declines in mate-searching efficiency due to habitat fragmentation. The model predicts that mating success will decline non-linearly if searching efficiency declines faster than habitat area, and increase non-linearly otherwise. Specifically for the Lancaster Sound population, we predict that female mating success would decline from 99% to 91% if searching efficiency declined twice as fast as sea ice area, and to 72% if searching efficiency declined four times as fast as area. Sea ice is a complex and dynamic habitat that is rapidly changing. Failure to incorporate climate change effects into population projections can result in flawed conservation assessments and management decisions.  相似文献   

2.
Although well-studied vertebrates such as the Northern Spotted Owl (NSO) are often used as focal species in regional conservation plans, range shifts associated with climate change may compromise this role. I used the Maxent (maximum entropy) method to develop NSO distribution models from data on NSO locations, forest age, and an ensemble of climate projections. NSO presence was positively associated with the proportion of old and mature forest at two spatial scales. Winter precipitation was the most important climate variable, consistent with previous studies suggesting negative effects on survival and recruitment. Model results suggest that initial niche expansion may be followed by a contraction as climate change intensifies, but this prediction is uncertain due to variability in predicted changes in precipitation between climate projections. Although new reserves created by the US Northwest Forest Plan prioritized areas with greater biological importance for the NSO than did pre-existing reserves, the latter areas, which lie predominantly at higher elevations, increase in importance under climate change. In contrast with previous analyses of the region’s localized old-forest-associated species, vegetation rather than climate dominated NSO distribution models. Rigorous assessment of the implications of climate change for focal species requires development of dynamic vegetation models that incorporate effects of competitor species and altered disturbance regimes. The results suggest that, lacking such data, models that combine climate data with current data on habitat factors such as vegetation can inform conservation planning by providing less-biased estimates of potential range shifts than do niche models based on climate variables alone.  相似文献   

3.
Conservation planning at broad spatial scales facilitates coherence between local land management and objectives set at the state or provincial level. Habitat suitability models are commonly used to identify key areas for conservation planning. The challenge is that habitat suitability models are data hungry, which limits their applicability to species for which detailed information exists, but managers need to address the needs of all at-risk species. We propose a modeling approach useful for regional-scale conservation planning that accommodates limited species knowledge, and identifies what managers should aim for at the local scale. For twenty at-risk bird species, we built models to identify potential habitat using both literature information and empirical data. Species occupancy within potential habitat depends on the presence of intrinsic elements, which we identified for each species so that managers can enhance these elements as appropriate. For most species, the estimated amount of habitat needed to meet population targets was <10% of the mapped potential habitat, with notable exceptions for Northern Goshawk (Accipiter gentilis; 100%), Brown Thrasher (Toxostoma rufum; 63.7%), and Veery (Catharus fuscescens; 17.9%). Model validation showed that interior forest species models performed best. Our modeling framework allowed us to build potential habitat models to various endpoints for different species, depending on the information available, and revealed a number of species for which basic natural history data are missing. Our potential habitat models provide regional perspective and guide local habitat management, and assist in identifying research priorities.  相似文献   

4.
Climate change is likely to affect the persistence of large, space-requiring species through habitat shifts, loss, and fragmentation. Anthropogenic land and resource use changes related to climate change can also impact the survival of wildlife. Thus, climate change has to be integrated into biodiversity conservation plans. We developed a hybrid approach to climate-adaptive conservation landscape planning for snow leopards in the Himalayan Mountains. We first mapped current snow leopard habitat using a mechanistic approach that incorporated field-based data, and then combined it with a climate impact model using a correlative approach. For the latter, we used statistical methods to test hypotheses about climatic drivers of treeline in the Himalaya and its potential response to climate change under three IPCC greenhouse gas emissions scenarios. We then assessed how change in treeline might affect the distribution of snow leopard habitat. Results indicate that about 30% of snow leopard habitat in the Himalaya may be lost due to a shifting treeline and consequent shrinking of the alpine zone, mostly along the southern edge of the range and in river valleys. But, a considerable amount of snow leopard habitat and linkages are likely to remain resilient to climate change, and these should be secured. This is because, as the area of snow leopard habitat fragments and shrinks, threats such as livestock grazing, retaliatory killing, and medicinal plant collection can intensify. We propose this approach for landscape conservation planning for other species with extensive spatial requirements that can also be umbrella species for overall biodiversity.  相似文献   

5.
Conservation planning is often based on static mapping of species’ ranges or habitat distributions. Succession and disturbance alter, however, habitat quality and quantity through time especially under global climate and land use change scenarios; hence, static protected areas may not ensure habitat persistence and species survival. Here, we examined the relative merits of static and dynamic (floating) protected areas for the conservation of American marten (Martes americana) habitat in a dynamic boreal forest of Québec (Canada). Forest dynamics were modeled using a spatially-explicit landscape disturbance model and protected areas were selected based on the quality and compactness of marten home ranges using MARXAN. Static protected areas were fixed in space during 200 year simulations of boreal forest dynamics, while dynamic protected areas were re-located every 50 years to track dynamic habitat. Dynamic protected areas supported more high quality home ranges through time than static protected areas. The locations of dynamic protected areas were constrained, however, by the highly fragmented forest patterns created through logging and fire in unprotected areas. Our findings emphasize the often-overlooked point that if dynamic conservation planning is to be successful in the long term, the landscape matrix quality surrounding protected areas must be managed in such a way that options remain when it comes to re-planning.  相似文献   

6.
We investigated the brown bear habitat suitability in an 8000 km2 study area encompassing Abruzzo, Latium, and Molise regions in central-southern Italy. Based on long-term field surveys and published records, we classified bear habitat as occupied or unoccupied in 92 out of 320 sample squares (5 × 5 km). For each sample square 36 habitat variables were measured from topographic maps and Corine land-cover III level digital maps. The influence of habitat features on bear presence was investigated by multivariate and one-way analyses of variance and by logistic regression analysis. The logistic model correctly classified 95.5% of sample squares of bear presence and 93.8% of those where bears were absent. Average altitude, deciduous woodlands and ecotone length, showed a positive relationship with bear presence, whereas vineyard-olive groves and shrublands were negatively correlated with bear presence. No specific land management guidelines or strategies exist for bear conservation in central Italy, based on knowledge of habitat-population relationships. The landscape scale habitat model we developed could be useful to predict bear occurrence, to identify critical areas for a brown bear conservation strategy, and to enhance the arrangement of the protected areas network for the conservation of this species.  相似文献   

7.
Broad-scale monitoring in Alaska has become of increasing interest due to uncertainty about the potential impacts of changing climate on high-latitude ecosystems. The Forest Inventory and Analysis (FIA) program is a national monitoring program for all public and private forestlands in the US, but the program is not currently implemented in the boreal region of Alaska. We provide an overview of the strengths and weaknesses of the FIA system for monitoring the potential impact of climate change on Alaska’s species, communities, and ecosystems. The primary strength of the system is a scientifically rigorous design-based statistical estimation method that produces estimates of forest attributes with known sampling error and quantifiable measurement error. The weaknesses of the system include low power for small area estimates, lack of spatial context and contiguity, and difficulty in inferring causality of factors when changes in monitored attributes are detected.Climate change is expected to impact many components of boreal ecosystems, but for most indicators the direction and magnitude of change are difficult to predict because of complex interactions among system components. Status and trend information provided by FIA monitoring that could be helpful to conservation decisions includes abundance and rarity of vascular plants, invasive species, biomass and carbon content of vegetation, shifting vegetation species distribution, disturbance frequency, type, and impact, and wildlife habitat characteristics. Because of unique factors such as the low level of infrastructure, modifications to the FIA monitoring system used in the conterminous US have been proposed for Alaska. Remote sensing data would play a greater role in meeting monitoring objectives, and sampling intensity of field plots would be reduced. Coordination with other national, regional, and local monitoring efforts provides potential for increased understanding of change in boreal ecosystems at multiple scales.  相似文献   

8.
Land ownership in Alaska includes a mosaic of federally managed units. Within its agency’s context, each unit has its own management strategy, authority, and resources of conservation concern, many of which are migratory animals. Though some units are geographically isolated, many are nevertheless linked by paths of abiotic and biotic flows, such as rivers, air masses, flyways, and terrestrial and aquatic migration routes. Furthermore, individual land units exist within the context of a larger landscape pattern of shifting conditions, requiring managers to understand at larger spatial scales the status and trends in the synchrony and spatial concurrence of species and associated suitable habitats. Results of these changes will determine the ability of Alaska lands to continue to: provide habitat for local and migratory species; absorb species whose ranges are shifting northward; and experience mitigation or exacerbation of climate change through positive and negative atmospheric feedbacks. We discuss the geographic and statutory contexts that influence development of ecological monitoring; argue for the inclusion of significant amounts of broad-scale monitoring; discuss the importance of defining clear programmatic and monitoring objectives; and draw from lessons learned from existing long-term, broad-scale monitoring programs to apply to the specific contexts relevant to high-latitude protected areas such as those in Alaska. Such areas are distinguished by their: marked seasonality; relatively large magnitudes of contemporary change in climatic parameters; and relative inaccessibility due to broad spatial extent, very low (or zero) road density, and steep and glaciated areas. For ecological monitoring to effectively support management decisions in high-latitude areas such as Alaska, a monitoring program ideally would be structured to address the actual spatial and temporal scales of relevant processes, rather than the artificial boundaries of individual land-management units. Heuristic models provide a means by which to integrate understanding of ecosystem structure, composition, and function, in the midst of numerous ecosystem drivers.  相似文献   

9.
Estimating historic distributions of species is a critical step in evaluating current levels of habitat loss, evaluating sites for potential restoration and reintroductions, and for conservation planning at a landscape scale. However historic distributions can be difficult to estimate objectively because substantial habitat changes may have occurred prior to comprehensive surveys. As a means to address this question, we evaluated a novel approach by creating spatial niche models for two species of psammophilic lizards. Using a partitioned Mahalanobis D2 analysis and abiotic variables that were independent of anthropogenic change, we created niche models for the federally threatened Coachella Valley fringe-toed lizard (Uma inornata) and for the flat-tailed horned lizard (Phrynosoma mcallii). The niche models estimated that within the Coachella Valley there were originally 32,164 ha of potential habitat for the fringe-toed lizard and 33,502 ha of potential habitat for the horned lizard. After screening these estimates of historic habitat for current conditions that would render that potential habitat unsuitable, we calculated a 91-95% loss of potential habitat for the fringe-toed lizard and an 83-92% loss for the horned lizard. Unlike the fringe-toed lizard, the horned lizard also occurs outside the Coachella Valley. Conducting a similar analysis throughout its range would provide an objective estimate of the total habitat loss experienced by this species. This information could be used to address whether granting it federal or state protection is warranted. For species whose distributions can be modeled with abiotic variables such as soils, elevation, topography, and climate, this approach may have broad applications for resolving questions regarding their current levels of habitat loss and regional conservation planning.  相似文献   

10.
The primary habitat for polar bears is sea ice, yet unlike most of the high Arctic, Hudson Bay undergoes a summer ice-free period that forces all bears ashore until ice forms again in fall. Polar bear populations in the greater Hudson Bay region have been placed in four management units based primarily on data from tag returns from harvested animals, capture-recapture studies, and conventional and satellite telemetry. Our results indicate that there is a high level of gene flow among management units observed using 26 microsatellite loci and analysis of genetic profiles of 377 polar bears. However, individual-based Bayesian analysis identified population genetic structuring into three clusters and significant FST differentiation. Specifically, our data suggest differentiation of polar bears sampled from islands in James Bay. These results were in spite of the extensive dispersal capabilities of polar bears that could homogenize the population. Mapping of high-ancestry individuals suggests that two of the three clusters have foci in southern Hudson Bay and may be a result of predictable annual freeze-thaw patterns that are maintaining breeding ‘groups’. Predicted changes in the distribution and duration of sea ice in Hudson Bay suggest that gene flow among these clusters may be reduced in the future.  相似文献   

11.
How populations from different regions within the distribution of a species contribute to the adaptive potential and survival of that species has important implications for formulating conservation actions. We test assumptions of concepts on geographic population structure (e.g. central-marginal concept and ‘rear edge versus leading edge’ model) that could be used to inform conservation of plant species under climatic changes. We analyze a comprehensive dataset of demographic traits (e.g. population size, flowering, δ13C of plant leaves) of up to 32 sites of Himantoglossum hircinum (L.) Spreng. (Orchidaceae) located within six sub-regions of its European distribution range. Soil and climate parameters are employed as environmental predictors of variation in measured population traits. Climate is the main driver of demographic variability overriding central-marginal gradients that might be present. Warming of the climate at high latitudes paves the way for northward range expansion of species. Populations at the north and north-eastern range peripheries partly show exponential population growth and high genetic diversity and are likely to be the source of immigrants for colonization of newly suitable habitats as the climate continues to change. In recent times, populations at the southern range periphery have suffered from intensification of land use and decreasing rainfall, but in the case of Southern Italy are important because they contain genetically unique traits. Populations at both, ‘leading’ and ‘rear’, edges ought to be at the focus of conservation planning. Different conservation strategies are proposed at opposing species borders taking into account spatial variation in population needs on a geographic scale, projected population response to expected environmental changes and genetic characteristics.  相似文献   

12.
Biodiversity conservation policies focus on securing the survival of species and habitats according to their current distribution. This basic premise may be inappropriate for halting biodiversity decline under the dynamic changes caused by climate change. This study explores a dynamic spatial conservation prioritization problem where climate change gradually changes the future habitat suitability of a site’ current species. This has implications for survival probability, as well as for species that potentially immigrate to the site. The problem is explored using a set of heuristics for both of two policy objectives focusing on (1) the protection on current (native) species, and (2) all species, including immigrating species. The trade-offs between the protection of native species versus all species is illustrated. The study shows that the development of prediction models of future species distributions as the basis of decision rules can be crucial for ensuring the effectiveness of conservation plans. Finally, it is discussed how more adaptive strategies, that allow for the redirection of resources from protected sites to privately-owned sites, may increase the effectiveness of the conservation networks. Climate change induced shifts in the suitability of habitats for species may increase the value of such adaptive strategies, the benefit decreasing with increasing migration probabilities and species distribution dynamics.  相似文献   

13.
Climate change has created the need for new strategies in conservation planning that account for the dynamics of factors threatening endangered species.Here we assessed climate change threat to the European otter, a flagship species for freshwater ecosystems, considering how current conservation areas will perform in preserving the species in a climatically changed future. We used an ensemble forecasting approach considering six modelling techniques applied to eleven subsets of otter occurrences across Europe. We performed a pseudo-independent and an internal evaluation of predictions. Future projections of species distribution were made considering the A2 and B2 scenarios for 2080 across three climate models: CCCMA-CGCM2, CSIRO-MK2 and HCCPR HADCM3. The current and the predicted otter distributions were used to identify priority areas for the conservation of the species, and overlapped to existing network of protected areas.Our projections show that climate change may profoundly reshuffle the otter’s potential distribution in Europe, with important differences between the two scenarios we considered. Overall, the priority areas for conservation of the otter in Europe appear to be unevenly covered by the existing network of protected areas, with the current conservation efforts being insufficient in most cases. For a better conservation, the existing protected areas should be integrated within a more general conservation and management strategy incorporating climate change projections. Due to the important role that the otter plays for freshwater habitats, our study further highlights the potential sensitivity of freshwater habitats in Europe to climate change.  相似文献   

14.
Research has shown that avian malaria plays an important role in limiting the distribution and population sizes of many Hawaiian birds, and that projected climate change is likely to eliminate most disease-free habitat in Hawai’i in the next century. I used a modeling approach, parameterized with demographic data from the literature and the field, to examine alternate management scenarios for the conservation of native Hawaiian birds. I examined the feasibility of using management in the form of rodent control to facilitate the evolution of resistance to malaria by increasing the survival and reproduction of native birds. Analysis of demographic data from seven native species, Akepa (Loxops coccineus), ‘Akohekohe (Palmeria dolei), Elepaio (Chasiempis sandwichensis), Hawai’i’amakihi (Hemignathus virens), Hawai’i creeper (Oreomystis mana), Omao (Myadestes obscurus), and Palila (Loxioides bailleui), suggest that differences in life history cause some species to be more susceptible to local extinctions from the transmission of malaria. Modeling results demonstrated that rodent control at middle, but not high, elevations can facilitate the evolution of resistance to malaria in several species of Hawaiian birds. Advocating a management approach that encourages evolutionary change in endangered species contrasts with the traditional conservation paradigm but it may be the best strategy to reduce the impacts of one of the multiple stressors that have devastated the native bird community of Hawai’i.  相似文献   

15.
Rapid land-use and climate changes are projected to cause broad-scale global land-cover transformation that will increase species extinction rates. We assessed the exposure of globally threatened plant biodiversity to future habitat loss over the first half of this century by testing country-level associations between threatened plant species richness and future habitat loss owing to land-use and climate changes, separately. In countries overlapping Biodiversity Hotspots, plant species endangerment increases with climate change-driven habitat loss. This association suggests that many currently threatened plant species will become extinct owing to anthropogenic climate change in the absence of potentially mitigating factors such as natural and assisted range shift, and physiological and genetic adaptations. Countries rich in threatened species, which are also projected to have relatively high total future habitat loss, are concentrated around the equator. Because poverty and poor governance can compromise conservation, we considered the economic condition and quality of governance with the degree of plant species endangerment and future habitat loss to prioritize countries based on conservation need. We identified Angola, Cuba, Democratic Republic of Congo, Ethiopia, Kenya, Laos, Madagascar, Myanmar, Nepal, Tajikistan, and Tanzania as the countries in greatest need of conservation assistance. For conservation endeavors to be effective, the conservation capacity of these high-need countries needs to be improved by assisting political stability and economic sustainability. We make policy recommendations that aim to mitigate climate change, promote plant species conservation, and improve the economic conditions and quality of governance in countries with high conservation need.  相似文献   

16.
Urban habitats, particularly wastelands and brownfields, maintain rich biodiversity and offer habitat for many species, even rare and endangered taxa. However, such habitats are also under socio-economic pressures due to redevelopment for housing and industrial uses. In order to maintain urban biodiversity, it is currently unknown how much open area must be preserved and whether conservation is possible without complete exclusion from economic development. In this study, we applied a simulation model based on species distribution models for plants, grasshoppers, and leafhoppers to investigate planning options for urban conservation with special focus on business areas. Altogether, we modelled the occurrence of 81 species of the urban species pool and analysed settings of different proportions of open sites, different habitat turnover times, and different lot sizes. Our simulations demonstrated that dynamic land use supports urban biodiversity in terms of species richness and rarity. Setting aside brownfields before redevelopment for a period of on average 15 years supported the highest conservation value. Consequently, we recommend integrating the concept of ‘temporary conservation’ into urban planning for industrial and business areas. This concept requires habitat to be destroyed by redeveloping brownfield sites to built-up sites, but simultaneously creating new open spaces due to abandonment of urban land uses at other locations. This maintains a spatio-temporal mosaic of different successional stages ranging from pioneer to pre-forest communities.  相似文献   

17.
Areas of high conservation value were identified in the Western Ghats using a systematic conservation planning approach. Surrogates were chosen and assessed for effectiveness on the basis of spatial congruence using Pearson’s correlations and Mantel’s tests. The surrogates were, threatened and endemic plant and vertebrate species, unfragmented forest areas, dry forests, sub-regionally rare vegetation types, and a remotely sensed surrogate for unique evergreen ecosystems. At the scale of this analysis, amphibian richness was most highly correlated with overall threatened and endemic species richness, whereas mammals, especially wide-ranging species, were better at capturing overall animal and habitat diversity. There was a significant relationship between a remote sensing based habitat surrogate and endemic tree diversity and composition. None of the taxa or habitats served as a complete surrogate for the others. Sites were prioritised on the basis of their irreplaceability value using all five surrogates. Two alternative reserve networks are presented, one with minimal representation of surrogates, and the second with 3 occurrences of each species and 25% of each habitat type. These networks cover 8% and 29% of the region respectively. Seventy percent of the completely irreplaceable sites are outside the current protected area network. While the existing protected area network meets the minimal representation target for 88% of the species chosen in this study and all of the habitat surrogates, it is not representative with regard to amphibians, endemic tree species and small mammals. Much of the prioritised unprotected area is under reserve forests and can thus be incorporated into a wider network of conservation areas.  相似文献   

18.
Human development often favors species adapted to human conditions with subsequent negative effects on sensitive species. This is occurring throughout the urbanizing world as increases by generalist omnivores, like some crows and ravens (corvids) threaten other birds with increased rates of nest predation. The process of corvid responses and their actual effects on other species is only vaguely understood, so we quantified the population response of radio-tagged American crows (Corvus brachyrhynchos), common ravens (Corvus corax), and Steller’s jays (Cyanocitta stelleri) to human settlements and campgrounds and examined their influence as nest predators on simulated marbled murrelet (Brachyramphus marmoratus) nests on Washington’s Olympic Peninsula from 1995 to 2000. The behavior and demography of crows, ravens, and jays was correlated to varying degrees with proximity to human development. Crows and ravens had smaller home ranges and higher reproduction near human settlements and recreation. Annual survival of crows was positively associated with proximity to human development. Home range and reproduction of Steller’s jays was independent of proximity to human settlements and campgrounds. Local density of crows increased because home ranges of neighboring breeding pairs overlapped extensively (6× more than ravens and 3× more than Steller’s jays) and breeders far from anthropogenic foods traveled 10s of kilometers to access them. Corvids accounted for 32.5% of the predation events (n = 837) we documented on artificial murrelet nests. Small corvids (jays) were common nest predators across our study area but their contribution as predators did not vary with proximity to settlements and campgrounds. In contrast, large corvids (crows and ravens) were rare nest predators across our study area but their contribution varied greatly with proximity to settlements and campgrounds. Managers seeking to reduce the risk of nest predation need to consider the varied impacts and variable behavioral and population responses of potential nest predators. In our situation, removing large corvids may do little to reduce overall rates of nest predation because of the diverse predator assemblage, but reducing anthropogenic food in the landscape may be effective.  相似文献   

19.
Scenario planning should be an effective tool for developing responses to climate change but will depend on ecological assessments of broad enough scope to support decision-making. Using climate projections from an ensemble of 16 models, we conducted an assessment of a midcontinental area of North America (Minnesota) based on a resistance, resilience, and facilitation framework. We assessed likely impacts and proposed options for eight landscape regions within the planning area. Climate change projections suggest that by 2069, average annual temperatures will increase 3 °C with a slight increase in precipitation (6%). Analogous climate locales currently prevail 400–500 km SSW. Although the effects of climate change may be resisted through intensive management of invasive species, herbivores, and disturbance regimes, conservation practices need to shift to facilitation and resilience. Key resilience actions include providing buffers for small reserves, expanding reserves that lack adequate environmental heterogeneity, prioritizing protection of likely climate refuges, and managing forests for multi-species and multi-aged stands. Modifying restoration practices to rely on seeding (not plants), enlarge seed zones, and include common species from nearby southerly or drier locales is a logical low-risk facilitation strategy. Monitoring “trailing edge” populations of rare species should be a high conservation priority to support decision-making related to assisted colonization. Ecological assessments that consider resistance, resilience, and facilitation actions during scenario planning is a productive first step towards effective climate change planning for biodiversity with broad applicability to many regions of the world.  相似文献   

20.
Climate and land-use changes are expected to cause many species to shift into or beyond the boundaries of protected areas, leading to large turnover in species composition. Here, we tested whether long-established protected areas in Canada were more robust to such climate change impacts than areas with no formal protection by measuring changes in modeled butterfly species distributions (n = 139) within them. We used a recently established distribution modeling technique, Maxent, to model butterfly species’ distributions in two epochs (1900-1930 and 1960-1990). We compared rates of butterfly species richness and composition change within protected areas against distributions of randomly selected, ecologically similar, but non-protected, areas. Change in species richness and composition within protected areas were, for the most part, the same as changes observed among random areas outside protected area boundaries. These results suggest that existing protected area networks in Canada have provided little buffer against the impacts of climate change on butterfly species richness, possibly because land-use change surrounding long-standing protected areas has not been substantial enough to elevate the habitat protection afforded by these protected areas relative to other areas. Although protected areas are unarguably beneficial in conserving biological diversity, their capacity to maintain habitat appears insufficient to prevent broader-scale climate changes from sweeping species beyond their boundaries.  相似文献   

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