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美国国有林经营及对中国的启示 总被引:3,自引:3,他引:0
在介绍美国国有林经营政策的基础上, 针对中国国有林经营现状, 提出应借鉴的经验:减轻税费负担, 加强营造林基础; 提高林业科技水平, 发展高效林业; 构建国有林资源法制化管理体系; 重视跨部门跨学科的交流和合作; 采用生态系统管理方法, 开发和保护并重。 相似文献
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Christopher M. Free Tracey Mangin John Wiedenmann Conner Smith Halley McVeigh Steven D. Gaines 《Fish and Fisheries》2023,24(2):248-262
Climate change is altering the productivity of marine fisheries and challenging the effectiveness of historical fisheries management. Harvest control rules, which describe the process for determining catch limits in fisheries, represent one pathway for promoting climate resilience. In the USA, flexibility in how regional management councils specify harvest control rules has spawned diverse approaches for reducing catch limits to precautionarily buffer against scientific and management uncertainty, some of which may be more or less resilient to climate change. Here, we synthesize the control rules used to manage all 507 US federally managed fish stocks and stock complexes. We classified these rules into seven typologies: (1) catch-based; (2) constant catch; (3) constant escapement; (4) constant F; (5) stepped F; (6) ramped F and (7) both stepped and ramped F. We also recorded whether the control rules included a biomass limit (‘cut-off’) value or were environmentally linked as well as the type and size of the buffers used to protect against scientific and/or management uncertainty. Finally, we review the advantages and disadvantages of each typology for managing fisheries under climate change and provide seven recommendations for updating harvest control rules to improve the resilience of US federally managed fisheries to climate change. 相似文献
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This paper addresses the question, when are threatened or endangered species really recovered? The US Endangered Species Act enables the de-listing of species once demographic criteria are met. In the Greater Yellowstone ecosystem, two protected apex carnivores, grizzly bears (Ursus arctos) and wolves (Canis lupus), face removal from federal government protection due to population increases, a point at which they are expected to be integrated components of this ecosystem. We tested the assumption that these two carnivores are playing normative ecological roles in the Yellowstone ecosystem by comparing the extent to which wolves and bears have re-instilled anti-predator responses in a primary prey species, moose (Alces alces), within wolf and bear recovery zones. As a type of control, we contrasted female moose from two areas in Alaska with different predator regimes to those in Wyoming. Populations from mainland Alaska, a region with a relatively intact carnivore assemblage, responded significantly more to odors of both carnivores. In contrast, a basic anti-predator reaction was lacking in Wyoming; and responses to grizzly bear odor only nominally increased after dependent young experienced heightened mortality. Additionally, the level of response among Alaskan moose living under virtual predator-free conditions for 25+ years closely resembled that of conspecifics in Wyoming. That such striking variation in prey responses exists re-enforces critical ecological differences between predator-intact and -defunct systems. Thus, although grizzly bears and wolves in the Yellowstone area will most likely be de-listed within the next few years, whether such action would be ecologically defensible is arguable. At this point in the recovery process, these predators may currently have limited ecological impacts in large portions of this region, at least as gauged by one potentially important prey species, moose. Although our data suggest ecologically incomplete conditions, other indices of carnivore recovery that include responses of other important prey species such as elk (Cervus elaphus), may be more in tune with carnivore activities. We recommend that different types of ecological data available throughout recovery zones be used in consort with demographic criteria to evaluate when endangered carnivores are more fully integrated into their ecosystems. And, in the event of a disparity between these criteria, we also encourage a dialogue focusing on approaches towards bringing ecological conditions in concordance with demographic criteria, irrespective of whether one considers increasing population levels beyond the current target levels required for de-listing,and/or simply, additional time for the recovery process. 相似文献
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阐述了我国农村地下水污染的严峻态势,分析了声誉罚、财产罚、行为罚、自由罚这4类行政处罚的实施现状,并说明了企业污染农村地下水行为防治中应用行为罚最为合理和有效,指出了行政处罚应用于农村地下水污染防治中的执法瓶颈;结合最新出台的《环境保护法》和目前地下水污染防治地方性立法的先进性,提出了对《水污染防治法》的修改建议。 相似文献
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This paper reports the results of a meta-analytic synthesis of information from a large number of horticultural experiments that evaluated the technical feasibility of methyl bromide alternatives as soil fumigants in strawberry (Fragaria ananassa) cultivation in California, Florida, and Spain, and in tomato (Solanum lycopersicum) cultivation in Florida. A technically feasible alternative is defined as a treatment that provides pest control and crop yields similar to methyl bromide standard fumigation. We selected papers using five criteria, which jointly ensured inclusion of field experiments that contained usable information on at least three treatments—(1) an untreated control, (2) a methyl bromide treatment, and (3) a treatment that is an alternative to methyl bromide treatment. Because of the differences in regional cropping environments, we performed separate meta-analyses for four crop/region combinations. To explore the potential effects of missing information on past fumigation history and pest pressure on the results, we performed two sensitivity analyses, in which the set of usable field experiments included only those experiments in which the improvement of the methyl bromide treatment yield over the control yield was either 15% or 50%. Finally, the definition of several potential alternative chemical treatments took into account differences in formulations and application rates. The results we obtained do not support the technical superiority of methyl bromide over its alternatives. We found several potential alternatives for which we could not reject the hypothesis of technical feasibility, based on the experimental data for strawberries in California and Spain. In particular, the results on strawberry field experiments in California indicate that the estimated effect size of the treatment using 1,3-dichloropropene/chloropicrin 65:35 formulation (applied at the standard rate) was close to the estimated effect size for methyl bromide. The results from strawberry and tomato field experiments in Florida were inconclusive. However, this does not establish that methyl bromide is technically superior to its alternatives. Given the data-related limitations of the analysis, standard protocols are necessary for conducting and reporting the experiments to allow for more meaningful synthesis of the experimental data. 相似文献
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To evaluate the sufficiency of US federal critical habitat designations and a proposed conservation plan in promoting the long-term persistence of the endangered plant Astragalus albens, patterns of genetic diversity and landscape connectivity were examined. A. albens harbors substantial genetic variation and shows no evidence of historic bottlenecks, suggesting little risk of extinction due to genetic homogeneity (A = 2.40; P = 0.50) or inbreeding (f = −0.08) within occurrences. Low genetic differentiation among occurrences (θp = 0.01) indicates relatively high gene flow or little genetic drift. The 91 patches of A. albens were connected into a single network at a distance of 2100 m; 94% of patches were <1000 m from at least one other patch. Managing ecological conditions that maintain large population sizes and connectivity among populations throughout the species’ ecological and geographic ranges will most likely conserve existing diversity. Both reserve networks partially accomplish these goals by including most extant occurrences and >89% of the aerial extent of the species, including the largest populations, and capturing all detected alleles. However, both conservation networks fail to conserve occurrences from one portion of the species’ range, possibly speeding loss of unique local adaptations. In addition, connectivity of the whole network is reduced with the 65 patches designated as critical habitat being connected at a distance of 6200 m and the proposed reserve sites being connected at a distance of 9500 m. Although total network connectivity would be reduced, connectivity at scales most relevant to gene flow (e.g., <1000 m) remains sufficiently in tact to provide a relatively promising outlook for species persistence. 相似文献
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对美国《濒危物种法》及其配套政策措施进行了介绍, 对其特点进行了分析总结; 在此基础上, 通过比较分析, 提出我国在野生物种保护的法律法规和保护实践方面有待加强和改进的方面。文中认为, 美国《濒危物种法》及其政策措施的特点主要体现在其自身的不断丰富和完善, 野生物种保护内容的完整性和科学性, 对政府执法机构、其他组织和个人在权责利关系方面的明确界定和有效协调, 公众的广泛参与, 重视对濒危名录外物种和私有土地上野生物种的保护等方面。我国在野生物种保护的立法和实践中需要在以下方面加强和改善:1)制定综合性的野生物种保护法, 协调政府各部门的执法行动; 2)加强我国野生物种保护法规体系的完整性和科学化; 3)完善公众参与野生物种保护的法规政策, 鼓励公众积极参与野生物种保护; 4)重视对未列入保护名录的野生物种的保护。 相似文献
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