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951.
The purpose of this paper is to identify trends in natural resource economics as reflected in publications in JEEM over the period since its inception in 1974. A secondary purpose is to suggest an explanation for any patterns we observe in the data. The data base consists of all articles published during this period, classified by topic and method. We apply statistical techniques of increasing sophistication to determine the existence of trends, and interpret the results by appealing to what we characterize as forces of demand and supply. 相似文献
952.
Environmental and Ecological Statistics - 相似文献
953.
954.
Maximum Plant-Community Endemism at Intermediate Intensities of Anthropogenic Disturbance in Bolivian Montane Forests 总被引:1,自引:0,他引:1
Michael Kessler 《Conservation biology》2001,15(3):634-641
Abstract: I compared the endemism of four plant groups (Araceae, Bromeliaceae, Palmae, Pteridophyta) along gradients of increasing anthropogenic forest disturbance, from undisturbed mature forest to disturbed forest (logged, grazed, or burned), secondary forest, secondary scrub, and finally pasture, at 16 sites in the Bolivian Andes. I measured endemism as the mean inverse range size (number of 1° cells) of all species per study group encountered in each habitat and site. Overall, endemism was significantly higher in disturbed forest than in mature forest, but it declined in more strongly disturbed habitats. To explain the relationship of range size to habitat disturbance, I propose that endemic species are somewhat competitively inferior to other co-occurring taxa, limited in their ability to establish and maintain new populations following dispersal and thus to expand their ranges. Within their established ranges, endemic species depend on natural habitat disturbances to prevent their competitive exclusion by other species, so they profit from a certain level of anthropogenic disturbance. This pattern and the explanatory hypotheses should be subjected to critical evaluation. Although the pattern does not apply to every endemic tropical plant species, it indicates that conservation of part of the endemic tropical forest flora may be achieved in forest areas subject to sustainable forest use without the need to completely exclude human activities. 相似文献
955.
956.
Water management in Uzbekistan (Central Asia) is facing tremendous challenges. They are rooted in past and present environmental degradation, the socio-economic transition after the breakup of the Soviet Union, and the impacts of climate change. The Uzbek government has initiated reforms in the agricultural and water sectors to steer the socio-economic transition and address the threats of increasing water scarcity and decreasing agricultural productivity. However, despite the urgency of the problems and massive international assistance changes to the water management regime have only been minimal so far. In this paper we identify major structural barriers for adaptation of the water management regime through an analysis of two recent policy processes. Both processes address pressing water management issues such as “coping with extreme events” and “providing water for ecosystems”. They were analyzed using the Management and Transition Framework as well as a group model building exercises with stakeholders on the national, regional and local levels. The analyses reveal a lack of vertical integration across administrative levels of the formal system and a still prevailing strong centralization of water management. Moreover the water management regime is strongly influenced by informal institutions that shape the outcomes of policy processes. The interactions guided by informal institutions provide an informal link between different administrative levels of the regime. However, those informal networks and the social capital embedded in them rather prevent needed changes. The resulting combination of top down institutional change initiated by socio-economic transition and bottom-up consolidation of the existing status quo via informal processes and networks prevents social learning. It also slows down an adaptation process that potentially could lead to a transition towards a more adaptive regime. 相似文献
957.
Subjective realities of climate change: how mental maps of impacts deliver socially sensible adaptation options 总被引:2,自引:0,他引:2
This paper discusses the perceived impacts of weather-related extreme events on different social groups in New Delhi, India. Using network statistics and scenario analysis with the Fuzzy Cognitive Mapping as part of a vulnerability analysis, the investigation provides quantitative and qualitative measures to compare impacts and adaptation strategies for different social groups. Impacts of rain events and heat waves are considered and differ across groups. Rain events affect the lower income classes more, while heat waves are the bigger burden for higher income classes. Overall, the strength of perceived impacts is larger for lower income classes, directly threatening their daily incomes. Urban managers have no immediate feedback on their livelihood, but often refer to health issues. The strongest effect on ameliorating burdens is investments in schemes to ease traffic, e.g., by improving the sewage and drainage infrastructure paired with other supply side measures to enable transport of goods for lower income classes during rain. During heat events, improving the water supply situation would reduce burden for all, while constant electricity supply is an effective means in reducing burden for the higher income classes in particular. Our analysis suggests that improvements in the water supply and sewage infrastructure would be the most suitable first step to initiate a well-planned adaptation strategy for all social groups. 相似文献
958.
Dale F. Rucker David A. Myers Brian Cubbage Marc T. Levitt Gillian E. Noonan Michael McNeill Colin Henderson Robert W. Lober 《Environmental monitoring and assessment》2013,185(1):995-1010
A characterization program has been developed at Hanford to image past leaks in and around the underground storage tank facilities. The program is based on electrical resistivity, a geophysical technique that maps the distribution of electrical properties of the subsurface. The method was shown to be immediately successful in open areas devoid of underground metallic infrastructure, due to the large contrast in material properties between the highly saline waste and the dry sandy host environment. The results in these areas, confirmed by a limited number of boreholes, demonstrate a tendency for the lateral extent of the underground waste plume to remain within the approximate footprint of the disposal facility. In infrastructure-rich areas, such as tank farms, the conventional application of electrical resistivity using small point-source surface electrodes initially presented a challenge for the resistivity method. The method was then adapted to directly use the buried infrastructure, specifically the steel-cased wells that surround the tanks, as “long” electrodes for both transmission of electrical current and measurements of voltage. Overcoming the drawbacks of the long electrode method has been the focus of our work over the past 7 years. The drawbacks include low vertical resolution and limited lateral coverage. The lateral coverage issue has been improved by supplementing the long electrodes with surface electrodes in areas devoid of infrastructure. The vertical resolution has been increased by developing borehole electrode arrays that can fit within the small-diameter drive casing of a direct push rig. The evolution of the program has led to some exceptional advances in the application of geophysical methods, including logistical deployment of the technology in hazardous areas, development of parallel processing resistivity inversion algorithms, and adapting the processing tools to accommodate electrodes of all shapes and locations. The program is accompanied by a full set of quality assurance procedures that cover the layout of sensors, measurement strategies, and software enhancements while insuring the integrity of stored data. The data have been shown to be useful in identifying previously unknown contaminant sources and defining the footprint of precipitation recharge barriers to retard the movement of existing contamination. 相似文献
959.
Sam M. Jones Jelle S. van Zweden Christoph Grüter Cristiano Menezes Denise A. Alves Patrícia Nunes-Silva Tomer Czaczkes Vera L. Imperatriz-Fonseca Francis L. W. Ratnieks 《Behavioral ecology and sociobiology》2012,66(1):1-12
Recent research has shown that entrance guards of the stingless bee Tetragonisca angustula make less errors in distinguishing nestmates from non-nestmates than all other bee species studied to date, but how they
achieve this is unknown. We performed four experiments to investigate nestmate recognition by entrance guards in T. angustula. We first investigated the effect of colony odours on acceptance. Nestmates that acquired odour from non-nestmate workers
were 63% more likely to be rejected while the acceptance rate of non-nestmates treated with nestmate odour increased by only
7%. We further hypothesised that guards standing on the wax entrance tube might use the tube as an odour referent. However,
our findings showed that there was no difference in the acceptance of non-nestmates by guards standing on their own colony’s
entrance tube versus the non-nestmate’s entrance tube. Moreover, treatment of bees with nestmate and non-nestmate resin or
wax had a negative effect on acceptance rates of up to 65%, regardless of the origin of the wax or resin. The role of resin
as a source of recognition cues was further investigated by unidirectionally transferring resin stores between colonies. Acceptance
rates of nestmates declined by 37% for hives that donated resin, contrasting with resin donor hives where acceptance of non-nestmates
increased by 21%. Overall, our results confirm the accuracy of nestmate recognition in T. angustula and reject the hypothesis that this high level of accuracy is due to the use of the wax entrance tubes as a referent for
colony odour. Our findings also suggest that odours directly acquired from resin serve no primary function as nestmate recognition
cues. The lack of consistency among colonies plus the complex results of the third and fourth experiments highlight the need
for further research on the role of nest materials and cuticular profiles in understanding nestmate recognition in T. angustula. 相似文献
960.
Cell-free DNA testing is increasingly being used to screen pregnant women for fetal aneuploidy. This technology may also identify microdeletion syndromes, including 22q11.2 deletion syndrome, the most common microdeletion syndrome, and the 22q11.2 duplication syndrome. The purpose of this paper is to provide an overview of the 22q11.2 deletion syndrome, to review the early experience with cell-free DNA screening for this deletion and to consider the potential benefits that may be associated with prenatal detection of the deletion. © 2016 John Wiley & Sons, Ltd. 相似文献