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1.
Poverty and corruption compromise tropical forest reserves.   总被引:1,自引:0,他引:1  
We used the global fire detection record provided by the satellite-based Moderate Resolution Imaging Spectroradiometer (MODIS) to determine the number of fires detected inside 823 tropical and subtropical moist forest reserves and for contiguous buffer areas 5, 10, and 15 km wide. The ratio of fire detection densities (detections per square kilometer) inside reserves to their contiguous buffer areas provided an index of reserve effectiveness. Fire detection density was significantly lower inside reserves than in paired, contiguous buffer areas but varied by five orders of magnitude among reserves. The buffer: reserve detection ratio varied by up to four orders of magnitude among reserves within a single country, and median values varied by three orders of magnitude among countries. Reserves tended to be least effective at reducing fire frequency in many poorer countries and in countries beset by corruption. Countries with the most successful reserves include Costa Rica, Jamaica, Malaysia, and Taiwan and the Indonesian island of Java. Countries with the most problematic reserves include Cambodia, Guatemala, Paraguay, and Sierra Leone and the Indonesian portion of Borneo. We provide fire detection density for 3964 tropical and subtropical reserves and their buffer areas in the hope that these data will expedite further analyses that might lead to improved management of tropical reserves.  相似文献   

2.
Abstract: In many areas of the developing world, the establishment of permanent marine reserves is inhibited by cultural norms or socioeconomic pressures. Community conserved areas that are periodically harvested are increasingly being implemented as fisheries management tools, but few researchers have empirically compared them with permanently closed reserves. We used a hierarchal control‐impact experimental design to compare the abundance and biomass of reef fishes, invertebrates, and substrate composition in periodically harvested and permanent reserves and in openly fished (control sites) of the South Pacific island country of Vanuatu. Fished species had significantly higher biomass in periodically harvested reserves than in adjacent openly fished areas. We did not detect differences in substratum composition between permanent reserves and openly fished areas or between permanent reserves and periodically harvested reserves. Giant clams (tridacnids) and top shells (Trochus niloticus) were vulnerable to periodic harvest, and we suggest that for adequate management of these species, periodically harvested community conservation areas be used in conjunction with other management strategies. Periodic harvest within reserves is an example of adaptive and flexible management that may meet conservation goals and that is suited to the social, economic, and cultural contexts of many coastal communities in the developing world.  相似文献   

3.
ABSTRACT

International food trade plays an important role in food security, but little research has been devoted to studying crop dynamics in importing countries caused by trade. We studied the spatiotemporal patterns of soybean planting area in China (the largest soybean importing country) in response to soybean imports. The results show how the soybean planting area from 1980 to 2012 in China is dominated by two temporal patterns, both of which first increased, then decreased, with an 8-year time lag. The first increasing-decreasing pattern is affected by increasing soybean imports, and the second increasing-decreasing pattern is driven by decreasing domestic soybean profits. The results also show spatially distinct spatial patterns: soybean planting area decreased in southeastern China while it increased in northwestern China. Our analysis of soybean planting area helps China and other food-importing countries understand spatiotemporal responses of domestic agricultural cultivations caused by international food trade and agricultural pollution management.  相似文献   

4.
Abstract. Many developing countries with high primate diversity are still forming wildlife reserves. However, financial resources for conservation in these countries are often limited. In this paper we show that the biology of reserve design in terms of island biogeography and minimum viable populations can be compatible with measures that minimize maintenance costs, namely perimeter surveillance. Large protected areas have substantially less perimeter to patrol than many small reserves of the same total area. Likewise, circular reserves have less perimeter than square or rectangular ones. Generally, countries with high primate diversity are using desirable strategies in design of nature reserves in terms of both finances and conservation; they have relatively large reserves and large amounts of area protected in relation to country size. However, some key primate-containing countries, such as Madagascar, Indonesia, and southeastern Brazil, require many small reserves to insure preservation of endemic taxa.  相似文献   

5.
I develop a state-based dynamic model of behavior to demonstrate that size-dependent differences in temperature tolerances are not necessary to account for the activity of small male digger wasps late in the day. In the model, males defend or patrol the nesting area, wait near nests, or feed away from the nesting area depending on time of day, energy reserves and size rank. I assume a large male competitive advantage, so mating opportunities decrease with size rank for territorial or patrolling males and are rare for all waiting males; the costs of patrolling or defense are higher than the costs of waiting. If energy reserves of all males are initially small, all males alternate feeding and territorial or patrolling behavior. If energy reserves are initially large, large males patrol or maintain territories until they risk starvation and leave the area to feed. At this time, smaller males that have conserved their resources by waiting and feeding may defend territories or patrol. I simulate the behavior of three populations representing two species of Microbembex by assuming large initial energy reserves for populations in which males were territorial and small initial reserves for populations in which males patrolled, and then convert the predicted time of activity to temperature using local regressions from field studies. Temporal patterns in the activity of large and small males were similar to those actually observed, and relationships between size and temperature predicted by the model corresponded to most observations and were sometimes positive. Thus, the delayed activity of smaller males does not correspond to activity at higher temperatures and is probably not attributable to size-dependent thermal tolerances, but may represent a temporal displacement of mating activity due to intra-sexual competition and mediated by energetics. The model makes testable predictions on the timing of feeding and depletion of energy reserves in relation to size and initial energy state, and suggests how differences among species may influence the temporal and spatial organization of male mating behavior. Received: 27 February 1997 / Accepted after revision: 26 July 1997  相似文献   

6.
Abstract: To understand how a highly contentious policy process influenced a major conservation effort, I examined the origins, compromises, and outcomes of the Alaska National Interest Lands Conservation Act of 1980 (ANILCA) for the Tongass National Forest. Tongass wilderness designation was among the most controversial issues in the ANILCA debate, and it faced strong opposition from influential lawmakers, land managers, and Alaska residents. To investigate the influence of this opposition on Tongass conservation outcomes, I conducted a gap analysis of Tongass reserves and a policy analysis of the ANILCA debate and traced the influence of specific interests through the amendments, negotiations, and resulting compromises needed to enact ANILCA. Overall, I found that Tongass reserves comprise a broadly representative cross‐section of ecosystems and species habitats in southeastern Alaska. Redrawn reserve boundaries, industry subsidies, and special access regulations reflected compromises to minimize the impact of wilderness conservation on mining, timber, and local stakeholder interests, respectively. Fragmentation of the Admiralty Island National Monument—the most ecologically valuable and politically controversial reserve—resulted from compromises with Alaskan Native (indigenous peoples of Alaska) corporations and timber interests. Despite language to accommodate “reasonable access” to wilderness reserves, ongoing access limitations highlight the concerns of Alaska residents that opposed ANILCA several decades ago. More broadly, the Tongass case suggests that early and ambitious conservation action may offset strong political opposition; compromises needed to establish key reserves often exacerbate development impacts in unprotected areas; and efforts to minimize social conflicts are needed to safeguard the long‐term viability of conservation measures.  相似文献   

7.
Protected Areas and Prospects for Endangered Species Conservation in Canada   总被引:3,自引:0,他引:3  
Abstract:  Reserve networks figure prominently in conservation strategies that aim to reduce extinction rates. We tested the effectiveness of the current reserve network at protecting species at risk in Canada, where relatively extensive wilderness areas remain. We compared numbers of terrestrial species at risk included in existing reserves to randomly generated networks with the same total area and number of reserves. Existing reserve networks rarely performed better than randomly selected areas and several included fewer endangered species than expected by chance, particularly in the most biologically imperiled regions. The extent of protected area and density of species at risk were unrelated at either broad (countrywide) or finer spatial scales (50 × 50 km grids), although there was a tendency for the most threatened regions of the country to have few or no protected areas (1.5% of areas with >30 endangered species were in reserves). Although reserves will play a useful role in conserving endangered species that occur within them, reducing extinction rates in a region with much of the world's remaining wilderness will require integrating conservation strategies with agricultural and urban land-use plans outside formally protected areas.  相似文献   

8.
Nature conservation in densely populated areas, as in western Europe, faces the continuous loss and fragmentation of suitable habitats for wild species. Current conservation measures have not been successful in countering this threat to biological diversity, so a new concept for nature conservation is required. I propose using the habitat requirements of large herbivores as a key to the design of large-scale nature reserves. Large herbivores can have a significant influence on vegetation composition and thus act as keystone species. Moreover, they require large tracts of land and can be considered an umbrella species group for the preservation of other plants and animals. I review the present status of nature reserves in the European Union concerning size distribution and the occurrence of large herbivores and their predators. I argue that habitat fragmentation and the increased management costs of maintaining seminatural areas necessitate an enlargement of existing reserves, a process-oriented management approach, and a minimization of human influence for the long-term preservation of biological diversity.  相似文献   

9.
Snow carb Chionoecetes opilio zoea I and zoea II larvae, hatched from females in a controlled mating experiment, were reared in the laboratory at 10.1 °C and 28.0 salinity, to resolve the patterns of growth (dry weight [DW]) and change in energy reserves (triacylglycerols [TAG]) within a given moult cycle. The patterns of growth and change in TAG reserves were similar in each zoeal stage. Following hatching or a moult, the zoeae entered a phase of rapid size increase, i.e. high daily growth rates (5.5 to 12.8% DWd-1), for 1/3 to 2/5 of the duration of the moult cycle. During the same period, the zoeae accumulated TAG reserves until a maximum (TAG DW-1) was reached at the end of the phase of rapid growth. The period of high growth rates and of TAG accumulation is interpreted as the required time for the zoeae to reach a point in development [i.e. point of reserves saturation (PRS); Anger and Dawirs (1981)] where sufficient growth and energy reserves allow moulting to the next stage. Following the phase of rapid growth and TAG accumulation, the zoeae entered a phase of low daily growth rates (0 to 1% DWd-1) during which the TAG reserves decreased to a minimum at the end of the phase. Prior to, and during the moult to zoea II, a phase of negative growth was observed in the zoea I larvae. We conclude that measurement of zoeal size and TAG content, along with morphometric criteria (e.g. epidermal retraction), can be used to assess growth and nutritional condition of C. opilio zoeal stages from the sea.  相似文献   

10.
A major goal of conservation biologists is to identify critical areas for the conservation of biological diversity and then strategically include them in an efficient system of reserves. In general, however, reserve networks have been selected for different objectives, and most countries lack an evaluation of their reserves' ability to represent a percentage of the national diversity. This paper evaluates the effectiveness of a network of reserves to represent the species of mammals in Mexico. The focus of the analyses is on species and site level, evaluating the representation of all terrestrial mammals in the 30 most important reserves. The representation of all species, endemic species, endangered species, and species with restricted distributions in the reserves was assessed and compared. Endemic or endangered species with restricted distributions were expected to be less represented in reserves than were widespread species. The most important reserves for the conservation of mammals were determined with the use of complementarity analyses. Priority sites for the representation of all the species currently absent from the reserve network were then selected. The results have broad applications for conservation. First, 82% of the mammal species from Mexico were represented in the reserve network, which covers a small portion (3.8%) of the country. Second, this percentage is certainly larger as several reserves were not evaluated due to a lack of data. A priority for a national conservation strategy could be to conduct biological surveys in those reserves lacking inventories to evaluate their contribution to conservation. Third, in spite of its demonstrated value, Mexico's reserve network can be improved by designating complementary areas. Additional priority sites, where reserves are required to represent most gap species in the network, were identified. Finally, it is clear that this reserve network has limitations for maintaining biodiversity and ecosystem services at regional scales. A comprehensive conservation strategy has, therefore, to incorporate mechanisms that enhance the value of human-dominated landscapes for the maintenance of biodiversity.  相似文献   

11.
分析了中国部分自然保护区面积与生物物种(动物和植物)之间的关系;其次讨论了动物与植物以及动物与动物物种数量间的关系.结果表明,我国部分自然保护区的面积多数偏小,鸟类、哺乳类、种子植物、爬行类、昆虫和两栖类等与其面积的相关关系依次减弱;其植物种数与鸟类种数的作用影响最大、关系最密切;两栖类与各类动物之间以及鸟类与各类动物之间的物种数目呈显著的相关关系;两栖类与昆虫类为负作用影响;鸟类与两栖类和爬行类以及哺乳类与两栖类为最大的正作用影响.  相似文献   

12.
The risk of predation may influence the acquisition of energy and the feeding activity of animals. Feeding activity and body reserves of wintering great tits Parus major in response to the priority to food access were studied in two areas differing in incidence of predators. The one-predator area contained sparrowhawks Accipiter nisus only, whereas the two-predator area contained both sparrowhawks and pygmy owls Glaucidium passerinum, whose hunting periods overlap at dawn and dusk. In the two-predator area dominant great tits arrived at feeders significantly later in the morning, and left earlier in the evening, than their subordinate flock-mates. Hence, feeding day length of dominants was found to be significantly shorter. The reverse was true for the one-predator area. In addition, dominants carried significantly greater reserves than subordinates in the area inhabited by two predators. Factors constraining subcutaneous energy reserves were also studied in removal experiments. After the removal of dominant individuals, subordinate great tits did not reduce their body reserves in the two predator area. In contrast, subordinate great tits significantly reduced evening body reserves in the single-predator area. I concluded that the presence of the two predators increases unpredictability in feeding conditions for great tits. Dominant individuals responded to this by shortening their feeding day and increasing body reserves at dusk. Received: 8 December 1999 / Received in revised form: 15 March 2000 / Accepted: 31 March 2000  相似文献   

13.
Abstract: Marine reserves have been suggested as tools for assisting the management of fisheries by protecting vulnerable marine species from overexploitation. Although there is a theoretical basis for believing that marine reserves may serve as management tools, there are few marine reserves in the world in which to test their effectiveness. My research evaluated three forms of marine reserve on the south coast of Vancouver Island, British Columbia, Canada. I used northern abalone ( Haliotis kamtschatkana ), a severely depleted shellfish in this region, as an indicator of the effectiveness of the reserves. Abalone populations in eight sites receiving different degrees of spatial protection were counted and measured in situ during the spring of 1996 and 1997. In all sites with enforced harvest closures, populations of abalone were greater, and one site with nearly 40 years of protection had on average much larger (older) abalone. Reproductive output, as a function of abundance and size, was also greater in the enforced reserve areas. Larval dispersal from reserves, and hence the benefit to exploited areas, was not formally surveyed. Nevertheless, the results of my study, combined with knowledge of present abalone populations, life history, and regional hydrodynamics, suggest that establishment of reserves is justified in the absence of perfect knowledge of larval dispersal.  相似文献   

14.
This study tested experimentally whether clutch size and the cost of care affect filial cannibalism in the sand goby, Pomatoschistus minutus. Evolutionary models of filial cannibalism suggest that egg eating has evolved as a way for the male parent to prolong his breeding season. These models assume that eggs function as an alternative energy source for the constrained parent. I manipulated clutch size by allowing males to mate with either one or two females, representing a small and a large clutch, respectively. The addition of a small male shore crab, a common egg predator, increased the cost of care. I quantified fat reserves as a measure of the condition of guarding males. Males who did not build nests had lower fat reserves than males who built nests, suggesting that males with low energy reserves do not start breeding. Males with small clutches lost their nest to the crab more often than males with large clutches. Neither filial cannibalism nor the amount of eggs eaten were affected by the treatments. Males who consumed eggs had a higher fat percentage than males who did not eat eggs. The result that males with small clutches lost their nests to the crabs supports the idea that eggs are defended only if the benefit from continued care will outweigh the cost and that males therefore are sensitive to the trade-off between present and future reproductive success. Received: 15 May 1997 / Accepted after revision: 15 November 1997  相似文献   

15.
Rafting on floating objects is a common dispersal mechanism for many marine invertebrates. In order to identify adaptations to the rafting life style, we compared behavioural and metabolic characteristics of two isopods, the obligate rafter Idotea metallica and the facultative rafter Idotea baltica. In laboratory experiments, I. metallica showed low locomotive activity and a tight association to the substratum. Idotea baltica, in contrast, was more active with more frequent excursions in the surrounding water column. Oxygen consumption rates were similar in both species. Idotea metallica fed on zooplankton making this species widely independent of autochthonous food resources of the raft. Feeding rates and digestive enzyme activities were low in I. metallica. Reduced egestion rates may indicate slow gut passage and, thus, efficient resorption of nutrients. Efficient food utilization and the ability to accumulate high amounts of storage products, i.e. lipids, indicate a possible adaptation of I. metallica to low food availability or starvation. The feeding behaviour of I. baltica, in contrast, was more herbivorous and appeared wasteful and inefficient. Low lipid contents in I. baltica also indicate poor storage reserves. Thus, I. baltica requires a permanent access to food.  相似文献   

16.
我国丹顶鹤自然保护区网络设计   总被引:5,自引:0,他引:5  
针对原有丹顶鹤保护区规划缺乏系统设计思想,保护区面临严重的生境安全这一问题,根据维持生态系统地域完整性和生态过程完整性的原则,采用迭代法和整数规划2种方法,以高、中适宜性湿地面积占各自湿地类型总面积70%和60%为保护目标,研究了丹顶鹤自然保护区的网络设计,提出了丹顶鹤自然保护区网络的设计方案。  相似文献   

17.
Abstract:  Fishing and other human activities can alter the abundances, size structure, and behavior of species playing key roles in shaping marine communities (e.g., keystone predators), which may in turn cause ecosystem shifts. Despite extensive evidence that cascading trophic interactions can underlie community-wide recovery inside no-take marine reserves by protecting high-level predators, the spatial extent of these effects into adjacent fished areas is unknown. I examined the potential for community-wide changes (i.e., the transition from overgrazed coralline barrens to macroalgal beds) in temperate rocky reefs within and around a no-take marine reserve. For this purpose I assessed distribution patterns of predatory fishes, sea urchins, and barrens across the reserve boundaries. Predatory fishes were significantly more abundant within the reserve than in adjacent locations, with moderate spillover across the reserve edges. In contrast, community-wide changes of benthic assemblages were apparent well beyond the reserve boundaries, which is consistent with temporary movements of predatory fishes (e.g., foraging migration) from the reserve to surrounding areas. My results suggest that no-take marine reserves can promote community-wide changes beyond their boundaries.  相似文献   

18.
In this paper, I show the existence and the characteristics of equilibrium in a non-renewable resource market where extraction costs are non-convex and market price is subject to stochastic shocks, an empirically relevant setting. In my model firms may be motivated to hold inventories to facilitate production smoothing, which allows them to continue producing at a smooth pace at any instant when extraction ceases, e.g. when reserves are exhausted. This aspect of the model then supports a competitive equilibrium in the presence of non-convex costs. Casual empirical evidence is provided that supports the central features of my model for a variety of non-renewable resources, lending credence to the explanation for equilibrium I propose.  相似文献   

19.
We present a conservation index based upon the interaction of the size of terrestrial protected areas, remaining forest habitat, deforestation rates, and biological richness to identify conservation potentials, threats, and strategies for 23 Indo-Pacific countries. This conservation potential/threat index shows that four of the largest and most species-rich countries—China, Indonesia, India, and Thailand—contain 82% of the region's large reserves (more than 1000 km2) and 86% of the region's area designated for protection. The skewed regional distribution and small number of large reserves per country call for the expansion of existing protected areas and, where possible the establishment of new parks and transfrontier reserves. The index indicates high potential for conservation efforts in Papua New Guinea, Laos, Myanmar, New Caledonia, Vanuatu, and the Solomon Islands, which have a high percentage of remaining forested habitats. high species richness, or endemism, but which lack comprehensive protected area systems. The index also predicts that if current rates of deforestation continue, only Brunei, Bhutan, Indonesia, Taiwan, and Malaysia will have adequate proportions of their respective land areas under some form of protection while still maintaining a minimal percentage (20% or more) of forested habitat outside reserves. Based on the regional analysis, we identify priority countries for investment in biodiversity conservation, and we evaluate funding responses earmarked for those countries. We then show how the index can be adapted to different geographical scales using examples from Indonesia, Malaysia, and the Philippines.  相似文献   

20.
In this paper, I show the existence and the characteristics of equilibrium in a non-renewable resource market where extraction costs are non-convex and market price is subject to stochastic shocks, an empirically relevant setting. In my model firms may be motivated to hold inventories to facilitate production smoothing, which allows them to continue producing at a smooth pace at any instant when extraction ceases, e.g. when reserves are exhausted. This aspect of the model then supports a competitive equilibrium in the presence of non-convex costs. Casual empirical evidence is provided that supports the central features of my model for a variety of non-renewable resources, lending credence to the explanation for equilibrium I propose.  相似文献   

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