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971.
The Melting Himalayas: Cascading Effects of Climate Change on Water, Biodiversity, and Livelihoods 总被引:4,自引:0,他引:4
Xu J Grumbine RE Shrestha A Eriksson M Yang X Wang Y Wilkes A 《Conservation biology》2009,23(3):520-530
Abstract: The Greater Himalayas hold the largest mass of ice outside polar regions and are the source of the 10 largest rivers in Asia. Rapid reduction in the volume of Himalayan glaciers due to climate change is occurring. The cascading effects of rising temperatures and loss of ice and snow in the region are affecting, for example, water availability (amounts, seasonality), biodiversity (endemic species, predator–prey relations), ecosystem boundary shifts (tree-line movements, high-elevation ecosystem changes), and global feedbacks (monsoonal shifts, loss of soil carbon). Climate change will also have environmental and social impacts that will likely increase uncertainty in water supplies and agricultural production for human populations across Asia. A common understanding of climate change needs to be developed through regional and local-scale research so that mitigation and adaptation strategies can be identified and implemented. The challenges brought about by climate change in the Greater Himalayas can only be addressed through increased regional collaboration in scientific research and policy making. 相似文献
972.
Species interactions such as predation or competition can have notable implications for fish population dynamics. Stock status and associated biological reference points can be misrepresented if these interactions are not considered. Here we present a multispecies, biomass production model (MS-PROD) developed by incorporating modifications to the Schaefer production model. The modifications explicitly emphasize a functional group approach, highlighting the effects of species interactions that include competition between species within a group, competition between groups, and predation. The mathematical formulation also includes constraints on carrying capacity for both the entire system and for individual groups. We applied the model as initialized to the Northeast U.S. Large Marine Ecosystem finfish community. We then executed simulations designed to explore the behavior of the model with respect to fishery exploitation and ecological interactions. Collectively, the results demonstrated the utility, and the need, for incorporating ecological effects into fisheries models. 相似文献
973.
Walter D. Koenig Eric L. Walters Joseph Haydock 《Behavioral ecology and sociobiology》2009,63(11):1659-1665
In cooperatively breeding acorn woodpeckers (Melanerpes formicivorus), helper males have a large positive effect on fledging success in good acorn crop years but only a small positive effect
in poor acorn crop years, while helper females exhibit the opposite pattern. Based on these findings, we tested the “concealed
helper effects” hypothesis, which proposes that laying females reduce investment in eggs (with respect to their size, number,
or quality) in a way that confounds helper effects and results in an absence of a relationship between helpers and breeding
success. Results generally failed to support the hypothesis. Mean egg size was positively related to temperatures during the
10 days prior to egg-laying and negatively related to the food supply as indexed by the prior fall’s acorn crop, but there
were no significant differences vis-à-vis helpers except for interactions with the acorn crop that only partly corresponded
to those predicted. With respect to clutch size, females laid larger clutches when assisted by female helpers, opposite the
pattern predicted. Although our results suggest that egg size is adjusted to particular ecological circumstances, we conclude
that neither egg nor clutch size is adjusted in a way that confounds the apparent effects of helpers, as proposed by the concealed
helper effects hypothesis. 相似文献
974.
S. P. Henzi D. Lusseau T. Weingrill C. P. van Schaik L. Barrett 《Behavioral ecology and sociobiology》2009,63(7):1015-1021
There is an established and very influential view that primate societies have identifiable, persistent social organizations.
It assumes that association patterns reflect long-term strategic interests that are not qualitatively perturbed by short-term
environmental variability. We used data from two baboon troops in markedly different habitats over three consecutive seasons
to test this assumption. Our results demonstrate pronounced cyclicity in the extent to which females maintained differentiated
relationships. When food was plentiful, the companionships identified by social network analysis in the food-scarce season
disappeared and were replaced by casual acquaintanceships more representative of mere gregariousness. Data from the fourth,
food-scarce, season at one site indicated that few companions were re-united. It is likely that this reflected stochastic
variation in individual circumstances. These results suggest that attention could profitably be paid to the effects of short-term
local contingencies on social dynamics, and has implications for current theories of primate cognitive evolution.
This contribution is part of the special issue “Social Networks: new perspectives” (Guest Editors: J. Krause, D. Lusseau and
R. James). 相似文献
975.
水库水源水生物陶粒滤池预处理中试研究 总被引:11,自引:0,他引:11
针对受污染的某水库水源水进行中试规模的生物陶粒滤池试验研究。试验结果表明,生物陶粒滤池预处理能全面净化水源水的水质。在气水比为0.75~1∶1,水力负荷为4~6 m3/(m2·h)条件下,对NH+4-N,NO-2-N和CODMn的去除率分别为89%~97.5%,97.5%~99%,20%~35%;对藻类的去除率为60.1%~84.3%。 相似文献
976.
DAVID G. STREETS LEYLA HEDAYAT GREGORY R. CARMICHAEL RICHARD L. ARNDT L. DOUGLAS CARTER 《Environmental management》1999,23(3):279-295
/ Air quality in most Asian cities is poor and getting worse. It will soon become impossible to sustain population, economic, and industrial growth without severe deterioration of the atmospheric environment. This paper addresses the city of Shanghai, the air-quality problems it faces over the next 30 years, and the potential of advanced technology to alleviate these problems. Population, energy consumption, and emission profiles are developed for the city at 0.1 degrees x 0.1 degrees resolution and extrapolated from 1990 to 2020 using sector-specific economic growth factors. Within the context of the RAINS-Asia model, eight technology scenarios are examined for their effects on ambient concentrations of sulfur dioxide and sulfate and their emission control costs. Without new control measures, it is projected that the number of people exposed to sulfur dioxide concentrations in excess of guidelines established by the World Health Organization will rise from 650,000 in 1990 to more than 14 million in 2020. It is apparent that efforts to reduce emissions are likely to have significant health benefits, measured in terms of the cost of reducing the number of people exposed to concentrations in excess of the guidelines ($10-50 annually per person protected). Focusing efforts on the control of new coal-fired power plants and industrial facilities has the greatest benefit. However, none of the scenarios examined is alone capable of arresting the increases in emissions, concentrations, and population exposure. It is concluded that combinations of stringent scenarios in several sectors will be necessary to stabilize the situation, at a potential cost of $500 million annually by the year 2020. KEY WORDS: Coal; China; Shanghai; Sulfur dioxide; Air quality; Health effects 相似文献
977.
Natasha B. Kotliar Bruce W. Baker April D. Whicker Glenn Plumb 《Environmental management》1999,24(2):177-192
Cynomys spp.) have been labeled as keystone species because of their influence on biological diversity and ecosystem function. However,
the validity of several assumptions used to support keystone status is questionable. We review the strength of the evidence
and the magnitude of the prairie dog's effects on ecosystem structure and function. We use this review to reevaluate the keystone
role for prairie dogs. Our goal is to encourage sound management of the prairie dog ecosystem by improving the ecological
foundation of their keystone status. Our review confirms that prairie dogs affect a number of ecosystem-level functions but
that their influence on prairie vertebrates may be less than previously suggested. Species richness and abundance patterns
were variable among plants, mammals, and birds and were not consistently higher on prairie dog colonies compared to uncolonized
areas. In addition, only nine of the 208 species listed in the literature as observed on or near prairie dogs colonies had
quantitative evidence of dependence on prairie dogs. Abundance data indicated opportunistic use of colonies for an additional
20 species. A total of 117 species may have some relationship with prairie dogs, but we lacked sufficient data to evaluate
the strength of this relationship. The remaining 62 species may be accidental or alien to the system. Despite our conclusion
that some prairie dog functions may be smaller than previously assumed, collectively these functions are quite large compared
to other herbivores in the system. We suggest that prairie dogs also provide some unique functions not duplicated by any other
species and that continued decline of prairie dogs may lead to a substantial erosion of biological diversity and landscape
heterogeneity across prairie and shrub-steppe landscapes. Thus, we concur that keystone status for prairie dogs is appropriate
and may aid conservation efforts that help protect species dependent on prairie dogs and support other important ecosystem
functions. 相似文献
978.
A review of personal care products in the aquatic environment: environmental concentrations and toxicity 总被引:6,自引:0,他引:6
Considerable research has been conducted examining occurrence and effects of human use pharmaceuticals in the aquatic environment; however, relatively little research has been conducted examining personal care products although they are found more often and in higher concentrations than pharmaceuticals. Personal care products are continually released into the aquatic environment and are biologically active and persistent. This article examines the acute and chronic toxicity data available for personal care products and highlights areas of concern. Toxicity and environmental data were synergized to develop a preliminary hazard assessment in which only triclosan and triclocarban presented any hazard. However, numerous PCPs including triclosan, paraben preservatives, and UV filters have evidence suggesting endocrine effects in aquatic organisms and thus need to be investigated and incorporated in definitive risk assessments. Additional data pertaining to environmental concentrations of UV filters and parabens, in vivo toxicity data for parabens, and potential for bioaccumulation of PCPs needs to obtained to develop definitive aquatic risk assessments. 相似文献
979.
Ammonium nitrate is one of the most widespread contaminants related with the viability of natural amphibian populations. In this study we have evaluated in terms of mortality and total length the effects that a previous sublethal pulse to ammonium nitrate generates in Epidalea calamita. Experiments were divided in two phases. In the first one, tadpoles were exposed to two different treatments, with and without a low ammonium nitrate concentration (22 mg NH4NO3 L−1). The second phase consisted in static toxicity experiments from both origin treatments with five different nominal concentrations (0, 22, 45, 90 and 180 mg NH4NO3 L−1). Results showed that tadpoles that had experienced a previous sublethal exposure showed a negative effect on survival (57% of reduction in the LC50 value) and total length, throughout an increase in their sensitivity. These results could help us to understand the situation of amphibian populations inhabiting aquatic ecosystems exposed to discontinuous and variable pulses of pollutants. 相似文献
980.
土地督察的耕地保护效果评价 总被引:1,自引:0,他引:1
为分析土地督察的耕地保护效果,论文把这目标分解为两个问题,即土地督察制度的实施是否对减少建设占用耕地面积产生了影响;如果有显著影响,效果有多大.论文收集了1999-2007年的省级面版数据,分别采用了固定效应模型、随机效应和混合OLS模型加以估计,通过相关检验,采用了固定效应模型的估计结果.在模型估计结果的基础上,对土地督察的耕地效果进行了评价.分析表明:①土地督察的确对减少建设占用耕地面积有显著影响,土地例行督察的耕地保护效果要好于土地专项督察的耕地保护效果,土地专项督察比例(每提高1%,约能减少建设占用耕地面积为261 hm<'2>,例行督察比例每提高1%,约能减少建设占用耕地面积为929 hm<'2>;②由于实施专项督察,2007年和2008年分别减少建设占用耕地面积32 160.52 hm<'2>和6 442.90 hm<'2>,分别占当年建设占用耕地面积的17.08%和3.36%;2008年由于实行了土地例行督察,减少建设占用耕地面积41 127.79 hm<'2>,约占当年建设占用耕地面积的21.5%;③由于实行了土地例行督察和专项督察,2007年和2008年分别减少建设占用耕地面积32 160.52 hm<'2>和47 570.70 hm<'2>,分别占当年建设占用耕地面积的17.08%和24.83%. 相似文献