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 62 毫秒
1.
2.
3.
分别对我省桔园的现状、"密改稀"的优越性及"密改稀"的技术要点及如何利用抬移树重新建园的有关技术进行了总结.  相似文献   

4.
5.
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   

6.
Mitigation of Habitat "Take": Application to Habitat Conservation Planning   总被引:2,自引:0,他引:2  
One of the most important provisions of the U.S. Endangered Species Act precludes the "taking" of listed species on both public and private land. In past Endangered Species Act litigation, take has been broadly interpreted to include the destruction or modification of habitats as well as the direct killing of animals. This requirement created an extensive burden on private landowners to provide habitats for listed species. This burden was substantially lessened when the ESA was modified in 1982 to allow incidental takings conditioned on preparation of a satisfactory "habitat conservation plan." Because the majority of listed species are imperiled due to habitat modification, most habitat conservation plans must demonstrate defensible methods to mitigate against incidental habitat loss. A review of HCPs for the Northern Spotted Owl ( Strix occidentalis), and other species, indicates that mitigation solutions are often arbitrary, lacking an empirical foundation in the species' life history requirements. Based on data from the Spotted Owl, we illustrate a biologically based method for estimating the areal requirements necessary to mitigate against the take of essential habitats. Toward this goal we adopt the concept of "core area," that portion of an animal's home range that receives disproportionate use. We estimated core areas by means of the adaptive kernel density function and tested against a null distribution of animal use that assumes a bivariate, uniform distribution of locations within the home range. The method we illustrate, which is defensible, repeatable, and empirical, is a clear improvement over the ad hoc methods used in many habitat conservation plans. Further, the methods we propose should be applicable to a large number of terrestrial species for which home range is a meaningful concept.  相似文献   

7.
本文论述了创新教育的概念、内容和知识经济时代高职院校实施创新教育的重要意义.提出了高职院校实施创新教育的方法和途径.  相似文献   

8.
创业教育划分为五个阶段:激发创业热情阶段、专业方向确立阶段、创业教育提升阶段、实习实训升华阶段和创业指导反馈阶段,在不同阶段采取不同的教学方式、传授不同的教学内容,达成不同的教学目标.创业教育应贯穿整个大学教育过程.参5.  相似文献   

9.
10.
This paper describes the catch composition in the rapido trawl fishery and the direct effects on non-target species. All data were collected on commercial fishing vessels so as to reflect commercial rapido-trawling practice. The effects on non-target species were measured using two different damage scales (three- and seven-level scales) depending on the morphology of the taxa. Damage assessment was performed taking into account the whole fishing process by collecting individuals that passed through the cod-end, individuals that were retained in the cod-end and dropped onto the deck and individuals that were collected at the end of the sorting operation just before their return to the sea. Due to differences in the habitat and spatial distribution of target species, discard/commercial ratio was very different among the three different target species fisheries: 1:6 in the queen scallop (Aequipecten opercularis) fishery, 2:1 in the flatfish (Solea spp., Platichthys flesus, Psetta maximus and Scophthalmus rhombus) fishery and 9:1 in the scallop (Pecten jacobaeus) fishery. Damage sustained by non-target species was species-specific and related to the morphology of different organisms. The sorting operation produced similar levels of injury to those of the gear itself: all discarded animals showed higher levels of damage after the sorting than before. Damage to animals that had passed through the cod-end followed the same pattern, and these data could give an estimate of the "unobserved mortality". Our observations indicated a higher impact on non-target species caused by the queen scallop fishery than that caused by the flatfish fishery. This could be due to the total amount of hard-shelled species (in the queen scallop fishery, A. opercularis accounted for 87% of the total catch biomass) in any given haul, since shells macerated the catch during towing. Discarded animals from the queen scallop fishery showed higher levels of damage than those collected in the flatfish fishery. The rapido trawl fishery seemed to exert a strong selective pressure on the macrobenthic community, being able to modify the epibenthic fauna structure which, in heavily exploited fishing grounds, was dominated by bivalves, gastropods, crabs, starfish and brittlestars.  相似文献   

11.
12.
阐述了当代第三条道路理论的形成背景及发展状况,并对第三条道路经济发展观的具体内容作了客观地阐述,然后就第三条道路经济观对当代中国经济发展的借鉴意义进行了有益的探讨.参13.  相似文献   

13.
Gilroy JJ  Virzi T  Boulton RL  Lockwood JL 《Ecology》2012,93(7):1509-1516
Survival estimates generated from live capture-mark-recapture studies may be negatively biased due to the permanent emigration of marked individuals from the study area. In the absence of a robust analytical solution, researchers typically sidestep this problem by simply reporting estimates using the term "apparent survival." Here, we present a hierarchical Bayesian multistate model designed to estimate true survival by accounting for predicted rates of permanent emigration. Initially we use dispersal kernels to generate spatial projections of dispersal probability around each capture location. From these projections, we estimate emigration probability for each marked individual and use the resulting values to generate bias-adjusted survival estimates from individual capture histories. When tested using simulated data sets featuring variable detection probabilities, survival rates, and dispersal patterns, the model consistently eliminated negative biases shown by apparent survival estimates from standard models. When applied to a case study concerning juvenile survival in the endangered Cape Sable Seaside Sparrow (Ammodramus maritimus mirabilis), bias-adjusted survival estimates increased more than twofold above apparent survival estimates. Our approach is applicable to any capture-mark-recapture study design and should be particularly valuable for organisms with dispersive juvenile life stages.  相似文献   

14.
步入21世纪,可持续发展战略实施力度加大.面对环境和国内外市场的严峻挑战,我国能源工业如何可持续发展,需要进行结构的战略调整.从政策思路上,要改变传统观念,把新能源和再生能源作为21世纪中叶我国的持续能源.促其产业化和本地化,改变地区开发的优先顺序,加大油气水电的政策支持力度.把利用国际油气资源列入国家规划.建立能源供应安全保障机制.对传统能源工业改组,改造.提出了"以大代小,同步调整"政策,大力开发煤炭洁净利用技术,建立市场节能机制,健全能源可持续发展的政策法规框架.  相似文献   

15.
16.
17.
18.
19.
三高农业与土壤和肥料有密切的关系。地力是作物产量的重要基础,要取得高产,就必须坚持不懈地培肥地力。综合地力、土壤中营养元素及有害或有毒物质的含量、肥料类型和施肥技术,都对农产品的品质有很大的影响。要提高农产品的产量和质量,就要因土种植,合理施肥。高产优质是经济效益的主要构成因素,因而,培肥地力、因土种植、合理施肥能提高经济效益。忽视土肥工作,将影响三高农业的发展。  相似文献   

20.
通过对原料林基地建设项目内容的分析 ,认为对“生态林”的界定标准 ,不能仅仅依据树木种类 ,还应考虑栽种的目的 ,这一观点在退耕还林的实际工作中具有一定的借鉴意义。  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