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41.
    
ABSTRACT: Subterranean ecosystems harbor globally rare fauna and important water resources, but ecological processes are poorly understood and are threatened by anthropogenic stresses. Ecosystem analyses were conducted from 1997 to 2000 in Cave Springs Cave, Arkansas, situated in a region of intensive land use, to determine the degree of habitat degradation and viability of endangered fauna. Organic matter budgeting quantified energy flux and documented the dominant input as dissolved organic matter and not gray bat guano (Myotis grisescens). Carbon/nitrogen stable isotope analyses described a trophic web of Ozark cavefish (Amblyopsis rosae) that primarily consumed cave isopods (Caecidotea stiladactyla), which in turn appeared to consume benthic matter originating from a complex mixture of soil, leaf litter, and anthropogenic wastes. Septic leachate, sewage sludge, and cow manure were suspected to augment the food web and were implicated in environmental degradation. Water, sediment, and animal tissue analyses detected excess nutrients, fecal bacteria, and toxic concentrations of metals. Community assemblage may have been altered: sensitive species‐grotto salamanders (Typhlotriton spelaeus) and stygobro‐mid amphipods—were not detected, while more resilient isopods flourished. Reduction of septic and agricultural waste inputs may be necessary to restore ecosystem dynamics in this cave ecosystem to its former undisturbed condition.  相似文献   
42.
This research investigates whether species are perceived differently based on aesthetic and negativistic attitudes, and whether these and other attitudes, naturalistic activities, and gender predict support for the protection of threatened species. 228 undergraduate students completed a survey in which they rated pictures of 10 endangered species on aesthetic and negativistic attitudes, and support for protection. Findings showed that the two-striped garter snake, Ozark big-eared bat, and dolloff cave spider were conceptualized differently than other species, which may be the result of “irrational” fears linked to animal phobias, culture, and emotional reactions to pictures. The regression results support the common belief that aesthetics is an important determinant in perceptions of endangered species and that the importance of negativistic attitudes may be waning. Moralistic worldviews and attitudes toward landowner rights and the Endangered Species Act were significantly related to support for governmental protection of species. Surprisingly, naturalistic activities and gender were not significantly associated with support for governmental protection of species. In general, the results were consistent across both models. However, the amount of variance explained by aesthetic and negativistic attitudes was 23 percent higher in the other species models than in the bat, snake, and spider models.  相似文献   
43.
外来赤潮生物入侵现状及对赤潮灾害的影响研究   总被引:1,自引:0,他引:1  
外来赤潮生物入侵加剧了我国近海海域的赤潮灾害。根据2004—2013年的数据统计,分别从赤潮生物优势种、频率、海域分布和赤潮面积4个方面分析了外来赤潮生物对我国近海赤潮灾害的影响,并着重从外来赤潮生物入侵早期预警系统建设、压舱水排放管理和赤潮灾害防治技术3个方面提出应对措施。  相似文献   
44.
对北戴河滨海区域森林景观植物资源种类及群落结构进行了实地调查和分析。结果表明:(1)所选样地植物种类共121种,其中园林观赏植物72种,滨海野生植物49种;(2)群落结构的模式主要以\"乔+灌+草\"为主。针对树种单一、乡土植物应用比例偏低、季相景观营造等问题,提出了丰富和补充植物种类,提高乡土植物应用比例,并协调搭配常绿植物与落叶植物,适当应用色叶树种等建议,营造北方滨海区域特色森林景观。  相似文献   
45.
    
Cordylanthus palmatus is a hemiparasitic annual of the family Scrophulareacae. It is on both the federal and state lists of endangered species. Only four widely separated populations remain, all of them in alkali sinks, where the plant thrives in saline-sodic soils. The largest population is at Springtown, Alameda County, California. This article reports on efforts to develop a management plan for both the plant and the alkali sink ecosystem. The plan is based on: (1) characterization of hydrology, soils and geomorphology of the site; (2) characterization of the land use impacts to the site; (3) analysis of plant distribution in relation to gradients of elevation and soil chemistry; (4) studies on water potential and water stress inCordylanthus palmatus and associated species. On the basis of this plan, both the State of California and private groups are cooperating to create, restore, and manage a preserve in the Springtown Alkali Sink.  相似文献   
46.
    
Most of Earth's biodiversity is found in 36 biodiversity hotspots, yet less than 10% natural intact vegetation remains. We calculated models projecting the future state of most of these hotspots for the year 2050, based on future climatic and agroeconomic pressure. Our models project an increasing demand for agricultural land resulting in the conversion of >50% of remaining natural intact vegetation in about one third of all hotspots, and in 2–6 hotspots resulting from climatic pressure. This confirms that, in the short term, habitat loss is of greater concern than climate change for hotspots and their biodiversity. Hotspots are most severely threatened in tropical Africa and parts of Asia, where demographic pressure and the demand for agricultural land is highest. The speed and magnitude of pristine habitat loss is, according to our models, much greater than previously shown when combining both scenarios on future climatic and agroeconomic pressure.  相似文献   
47.
    
Park design principles are proposed on the basis of consideration and analysis of rare plant species in Great Smoky Mountains National Park, USA. Rare species richness can be used as a simple measure of preservation success. A semilogartihmic species-area model for the Smokies was used in this analysis. Species richness would increase logarathmically with expansion of the national park area. An analysis of the relationship between species richness and the distribution of geologic and topographic features in the national park was also reported. An asymptotic relation was documented for the accumulation of newly recorded rare and endangered vascular plant species in the Smokies region up to 1978. Several multiple regression linear models predicted rare vascular plant species richness in Great Smoky Mountains National Park from area and topographic variates.Preserve design criteria can be based upon species-area, environmental gradient, and natural features distribution patterns for the specific taxa and biogeographic region under consideration. In addition, natural history characteristics for particular vulnerable species must be assessed. Rather than concentrating on the preservation of undocumented immigration and extinction processes, preserve design should be directed towards protecting geographic components and gradient patterns characteristic of a region.  相似文献   
48.
We followed selection guidelines commonly used by management agencies to select mountain quail (Oreortyx pictus) as an indicator species for an ecological guild of birds. We then evaluated the ability of mountain quail to indicate the presence of other species from the guild and to index the quality of the habitat for other species. The ability of quail to indicate the presence of species from the ecological guild varied widely within and among vegetation types. Species compositions of the ecological guild were more consistent in comparisons of sites within vegetation types than they were in comparisons of sites between vegetation types. Mountain quail habitat was significantly different from the habitats of sympatric species from the guild for 14 of 15 multivariate contrasts. We suggest that managers use indicator species with caution. If indicators are used, they should be applied to guilds composed of species that closely share ecological affinities. The habitat of the indicator species should overlap extensively with those of all other guild members. The use of indicators should be restricted to very similar sites within the same general vegetation type.  相似文献   
49.
This study conducts a choice experiment to determine the willingness to pay for Palouse Prairie conservation. The giant Palouse earthworm (Driloleirus americanus), a rare species endemic to the Palouse region, is included as an attribute of conservation and serves as a method for determining the willingness to pay for protecting the species. This method evaluates the value of the earthworm as an attribute of an overall willingness to pay for threatened ecosystem preservation rather than a direct willingness to pay for protecting the species. This method is expected to yield a more accurate measure of willingness to pay for rare species. The annual willingness to pay per household for the giant Palouse earthworm is $20.45 based on the conditional logit model and $19.30 based on the mixed logit model. Ranking and relative importance are included as methods for representing a non-monetary value and importance of the giant Palouse earthworm.  相似文献   
50.
简要叙述了中美两国新化学物质管理的基本情况,分别从管理原则、管理范围、管理具体要求、申报种类、评审程序、监督管理等方面重点论述了中美新化学物质管理制度的特点。通过借鉴美国新化学物质管理的优点及经验,提出了强化和完善中国新化学物质管理制度的对策。  相似文献   
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