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991.
Abstract: Genetic variation within species—a priority for biodiversity conservation—is influenced by natural selection, demography, and stochastic events such as genetic drift. We evaluated the role of these factors in 14 codistributed species of reptiles and amphibians on the Indonesian island of Halmahera by testing whether their molecular variation was correlated with geographic distance, ecology, riverine barriers, or Halmahera's paleoisland precursors. We found support for isolation by distance effects in four species. Two of these four were also significantly affected either by rivers or by ecology. A fifth species was significantly affected by ecology and a sixth was significantly affected by Halmahera's paleoislands. [Correction added after publication 9 December 2009: the previous sentence was edited for clarity.] These findings—the most comprehensive survey of multispecies genetic variation on Halmahera to date—bode well for the efficacy of the recently established Aketajawe‐Lolobata National Park in conserving a substantial component of vertebrate genetic variation on this island. Future success of conservation efforts will depend crucially, of course, on funding for and enforcement of conservation management of this park.  相似文献   
992.
Abstract: Local ecological knowledge can provide a unique source of data for conservation, especially in efforts to investigate the status of rare or possibly extinct species, but it is unlikely to remain constant over time. Loss of perspective about past ecological conditions caused by lack of communication between generations may create “shifting baseline syndrome,” in which younger generations are less aware of local species diversity or abundance in the recent past. This phenomenon has been widely discussed, but has rarely been examined quantitatively. We present new evidence of shifting baselines in local perception of regional species declines and on the duration of “community memory” of extinct species on the basis of extensive interviews with fishers in communities across the middle‐lower Yangtze basin. Many Yangtze species have experienced major declines in recent decades, and the Yangtze River dolphin or baiji (Lipotes vexillifer) and Yangtze paddlefish (Psephurus gladius) may have become extinct during the 21st century. Although informants across all age classes were strongly aware of the Yangtze ecosystem's escalating resource depletion and environmental degradation, older informants were more likely to recognize declines in two commercially important fish species, Reeves’ shad (Tenualosa reevesii) and Yangtze pufferfish (Takifugu fasciatus), and to have encountered baiji and paddlefish in the past. Age was also a strong predictor of whether informants had even heard of baiji or paddlefish, with younger informants being substantially less likely to recognize either species. A marked decrease in local knowledge about the Yangtze freshwater megafauna matched the time of major population declines of these species from the 1970s onwards, and paddlefish were already unknown to over 70% of all informants below the age of 40 and to those who first started fishing after 1995. This rapid rate of cultural baseline shift suggests that once even megafaunal species cease to be encountered on a fairly regular basis, they are rapidly forgotten by local communities.  相似文献   
993.
Abstract: Indicator species concepts have a long history in conservation biology. Arguments in favor of these approaches generally stress expediency and assume efficacy. We tested the premise that the abundance patterns of one species can be used to infer those of other species. Our data consisted of 72,495 bird observations on 55 species across 1046 plots distributed across 30 sub basins. We analyzed abundance patterns at two spatial scales (plot and sub basin) and for empirical and a priori grouping. There were few significant indicator relationships at either scale or under either grouping rule, and those few we found did not explain a substantial portion of the abundance of other species. Coupled with the lack of proven efficacy for species surrogacy in the literature, our results indicate the utility of indicators and similar types of surrogate approaches must be demonstrated rather than assumed.  相似文献   
994.
Abstract: Even under the most optimistic scenarios, during the next century human‐caused climate change will threaten many wild populations and species. The most useful conservation response is to enlarge and link protected areas to support range shifts by plants and animals. To prioritize land for reserves and linkages, some scientists attempt to chain together four highly uncertain models (emission scenarios, global air–ocean circulation, regional circulation, and biotic response). This approach has high risk of error propagation and compounding and produces outputs at a coarser scale than conservation decisions. Instead, we advocate identifying land facets—recurring landscape units with uniform topographic and soil attributes—and designing reserves and linkages for diversity and interspersion of these units. This coarse‐filter approach would conserve the arenas of biological activity, rather than the temporary occupants of those arenas. Integrative, context‐sensitive variables, such as insolation and topographic wetness, are useful for defining land facets. Classification procedures such as k‐means or fuzzy clustering are a good way to define land facets because they can analyze millions of pixels and are insensitive to case order. In regions lacking useful soil maps, river systems or riparian plants can indicate important facets. Conservation planners should set higher representation targets for rare and distinctive facets. High interspersion of land facets can promote ecological processes, evolutionary interaction, and range shift. Relevant studies suggest land‐facet diversity is a good surrogate for today's biodiversity, but fails to conserve some species. To minimize such failures, a reserve design based on land facets should complement, rather than replace, other approaches. Designs based on land facets are not biased toward data‐rich areas and can be applied where no maps of land cover exist.  相似文献   
995.
Abstract: Species occurrence in a habitat patch depends on local habitat and the amount of that habitat in the wider landscape. We used predictions from empirical landscape studies to set quantitative conservation criteria and targets in a multispecies and multiscale conservation planning effort. We used regression analyses to compare species richness and occurrence of five red‐listed lichens on 50 ancient oaks (Quercus robur; 120–140 cm in diameter) with the density of ancient oaks in circles of varying radius from each individual oak. Species richness and the occurrence of three of the five species were best explained by increasing density of oaks within 0.5 km; one species was best explained by the density of oaks within 2 km, and another was best predicted by the density of oaks within 5 km. The minimum numbers of ancient oaks required for “successful conservation” was defined as the number of oaks required to obtain a predicted local occurrence of 50% for all species included or a predicted local occurrence of 80% for all species included. These numbers of oaks were calculated for two relevant landscape scales (1 km2 and 13 km2) that corresponded to various species responses, in such a way that calculations also accounted for local number of oaks. Ten and seven of the 50 ancient oaks surveyed were situated in landscapes that already fulfilled criteria for successful conservation when the 50% and 80% criteria, respectively, were used to define the level of successful conservation. For cost‐efficient conservation, oak stands in the landscapes most suitable for successful conservation should be prioritized for conservation and management (e.g., grazing and planting of new oaks) at the expense of oak stands situated elsewhere.  相似文献   
996.
Abstract: Quality of the agricultural matrix profoundly affects biodiversity and dispersal in agricultural areas. Vegetatively complex coffee agroecosystems maintain species richness at larger distances from the forest. Epiphytes colonize canopy trees and provide resources for birds and insects and thus effects of agricultural production on epiphytes may affect other species. We compared diversity, composition, and vertical stratification of epiphytes in a forest fragment and in two coffee farms differing in management intensity in southern Mexico. We also examined spatial distribution of epiphytes with respect to the forest fragment to examine quality of the two agricultural matrix types for epiphyte conservation. We sampled vascular epiphytes in a forest fragment, a shade polyculture farm, and a shade monoculture farm at 100 m, 200 m, and 400 m from the forest. Epiphyte and orchid richness was greater in the forest than in the monoculture but richness was similar in the forest and polyculture farm. Epiphyte species composition differed with habitat type, but not with distance from the forest. In the forest, epiphytes were distributed throughout tree canopies, but in the farms, epiphytes were primarily found on trunks and larger branches. Epiphyte richness and species similarity to forest species declined with distance from the forest fragment in the monoculture, but richness and similarity to forest species did not decline with distance from forest in the polyculture. This suggests polyculture coffee has greater conservation value. In contrast, monoculture coffee is likely a sink habitat for epiphytes dispersing from forests into coffee. Coffee farms differ from forests in terms of the habitat they provide and species composition, thus protecting forest fragments is essential for epiphyte conservation. Nonetheless, in agricultural landscapes, vegetatively complex coffee farms may contribute to conservation of epiphytes more than other agricultural land uses.  相似文献   
997.
Abstract: Tradable permits have been applied in many areas of environmental policy and may be a response to increasing calls for flexible conservation instruments that successfully conserve biodiversity while allowing for economic development. The idea behind applying tradable permits to conservation is that developers wishing to turn land to economic purposes, thereby destroying valuable habitat, may only do so if they submit a permit to the conservation agency showing that habitat of at least the equivalent ecological value is restored elsewhere. The developer himself does not need to carry out the restoration, but may buy a permit from a third party, thus allowing a market to emerge. Nevertheless, the application of tradable permits to biodiversity conservation is a complex issue because destroyed and restored habitats are likely to differ. There may be various trade‐offs between the ecological requirements that destroyed and restored habitats be as similar as possible, and the need for a certain level of market activity to have a functioning trading system. The success of tradable permits as an instrument for reconciling the conflicts between economic development and conservation depends on the existence of certain economic, institutional, and ecological preconditions, for example, a functioning institutional framework, sufficient expert knowledge, and adequate monitoring and enforcement mechanisms.  相似文献   
998.
Abstract: Protected areas are a cornerstone of conservation and have been designed largely around terrestrial features. Freshwater species and ecosystems are highly imperiled, but the effectiveness of existing protected areas in representing freshwater features is poorly known. Using the inland waters of Michigan as a test case, we quantified the coverage of four key freshwater features (wetlands, riparian zones, groundwater recharge, rare species) within conservation lands and compared these with representation of terrestrial features. Wetlands were included within protected areas more often than expected by chance, but riparian zones were underrepresented across all (GAP 1–3) protected lands, particularly for headwater streams and large rivers. Nevertheless, within strictly protected lands (GAP 1–2), riparian zones were highly represented because of the contribution of the national Wild and Scenic Rivers Program. Representation of areas of groundwater recharge was generally proportional to area of the reserve network within watersheds, although a recharge hotspot associated with some of Michigan's most valued rivers is almost entirely unprotected. Species representation in protected areas differed significantly among obligate aquatic, wetland, and terrestrial species, with representation generally highest for terrestrial species and lowest for aquatic species. Our results illustrate the need to further evaluate and address the representation of freshwater features within protected areas and the value of broadening gap analysis and other protected‐areas assessments to include key ecosystem processes that are requisite to long‐term conservation of species and ecosystems. We conclude that terrestrially oriented protected‐area networks provide a weak safety net for aquatic features, which means complementary planning and management for both freshwater and terrestrial conservation targets is needed.  相似文献   
999.
Abstract: Statements of extinction will always be uncertain because of imperfect detection of species in the wild. Two errors can be made when declaring a species extinct. Extinction can be declared prematurely, with a resulting loss of protection and management intervention. Alternatively, limited conservation resources can be wasted attempting to protect a species that no longer exists. Rather than setting an arbitrary level of certainty at which to declare extinction, we argue that the decision must trade off the expected costs of both errors. Optimal decisions depend on the cost of continued intervention, the probability the species is extant, and the estimated value of management (the benefit of management times the value of the species). We illustrated our approach with three examples: the Dodo (Raphus cucullatus), the Ivory‐billed Woodpecker (U.S. subspecies Campephilus principalis principalis), and the mountain pygmy‐possum (Burramys parvus). The dodo was extremely unlikely to be extant, so managing and monitoring for it today would not be cost‐effective unless the value of management was extremely high. The probability the Ivory‐billed woodpecker is extant depended on whether recent controversial sightings were accepted. Without the recent controversial sightings, it was optimal to declare extinction of the species in 1965 at the latest. Accepting the recent controversial sightings, it was optimal to continue monitoring and managing until 2032 at the latest. The mountain pygmy‐possum is currently extant, with a rapidly declining sighting rate. It was optimal to conduct as many as 66 surveys without sighting before declaring the species extinct. The probability of persistence remained high even after many surveys without sighting because it was difficult to determine whether the species was extinct or undetected. If the value of management is high enough, continued intervention can be cost‐effective even if the species is likely to be extinct.  相似文献   
1000.
Killing Tigers to Save Them: Fallacies of the Farming Argument   总被引:1,自引:0,他引:1  
Abstract: The lucrative, illegal trade in tigers (Panthera tigris) remains a major conservation problem. Tiger farming has been proposed as a potential solution, with farmed tigers substituting for wild tigers. At first glance, this argument's logic seems simple: farming will increase the supply of tigers, prices will fall, and poaching will no longer be profitable. We contend, however, that this supply‐side argument relies on mistaken assumptions. First, tiger markets are imperfect, meaning they are dominated by a few producers who control price. Second, consumers prefer wild tigers to farmed tigers and therefore the two are not pure substitutes. In economic terms, products from wild tigers are luxury goods, commanding a price premium. Third, there is no evidence that farmed tigers can be produced or sold more cheaply than wild tigers. In sum, it is unlikely that farming will drive down the price of wild‐caught tigers or decrease profitability for tiger poachers. Rather, tiger farming is more likely to increase aggregate demand for tiger products and stimulate higher levels of poaching.  相似文献   
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