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1.
Variation in the reproduction of Varroa jacobsoni mite was studied in relation to the expansion of the range of its parasitism on the honeybee. Geographic differences in the seasonal dynamics of mite reproduction in the nests of bee families were revealed. Variation in the sex ratio of mites and the factors inhibiting their reproduction at the northern boundary of the honeybee range are considered. The forms of parthenogenetic reproduction in V. jacobsoni are discussed.  相似文献   

2.
湖南鼎城农业旱灾脆弱性的变化及原因分析   总被引:14,自引:3,他引:11  
农业旱灾的形成是降水不足或不均与农业生产系统脆弱性共同作用的结果,承灾体脆弱性的高低会起到“放大”或“缩小”灾情的作用,降低承灾体的脆弱性是抗灾减灾的主要和有效途径。选择湖南省鼎城区为研究区,发现在降水量及其季节分配相似,即致灾强度相似的两个年份(1988年和2001年),粮食因灾损失量前高后低。通过建立包括作物需水亏缺指数、耕地的灌溉便捷指数、耕地平坦指数、耕地生产投入指数等7个指标的评价指标体系,分别对1988年和2001年该区的农业旱灾承灾体脆弱性进行评价。结果显示该区的承灾体脆弱性明显降低,分析其原因,发现作物结构调整(中稻播种面积比例的适当增加)、耕地条件和生产力的改善、利用灌溉条件能力的提高有效地降低了该区农业旱灾承灾体脆弱性,减小了粮食生产的因灾损失。为致灾因子相似、承灾体脆弱性不同会“放大”或“缩小”灾情提供了实证案例。  相似文献   

3.
Productivity of the moss cover and necromass accumulation in the litter of a sphagnum larch forest have been estimated on the basis of tree age. It has been shown that the total carbon stock in the litter of a 100-year-old stand, including organic matter not destroyed by fire, exceeds the corresponding value for the tree stand itself by more than an order of magnitude. The accumulation of organic matter on the soil surface inhibits the growth of larch. In particular, this factor impairs hydrothermal conditions in the soil and causes a rise of the permafrost table; as a consequence, lower layers of the root system die off.  相似文献   

4.
Effects of toxic emissions (heavy metals and sulfur dioxide) on reproductive parameters of adult pied flycatchers (Ficedula hypoleuca Pall.) and morphophysiological characteristics of their progeny have been studied in the vicinity of the Middle Ural Copper-Smelting Plant. In polluted areas, the fecundity of adult birds is lower, mortality among the progeny is higher, and changes in the physiological parameters of birds are observed. The effects of toxic load are better manifested in nestlings than in adult birds. They include an increase in the liver index, the reduction of hemoglobin concentration, and an increase in the proportion of immature erythrocytes in the peripheral blood. The proportion of anemic birds also increases. The weakening of nestlings facilitates their infestation by the larvae of parasitic flies. Changes in the differential blood count of nestlings reflect the combined impact of toxic pollutants and parasites.  相似文献   

5.
Concentrations of radionuclides were measured in soils from a grid of locations surrounding the US Department of Energy Waste Isolation Pilot Plant (WIPP) in southeastern New Mexico and from a grid on a reference site approximately 20 km southeast of the WIPP site. Each of the two grids has 16 sampling locations (grid nodes) systematically distributed within an area of 16.580 ha. Sampling was conducted prior to the arrival of the first waste shipment at WIPP. Thus, the 137Cs and 23,240Pu in the soil are expected to have been deposited as global fallout, although the Gnome Site, 8.8 km southwest of the WIPP, is also a potential source of 239,240Pu and fission products. The reference grid has significantly higher concentrations of fallout and natural radionuclides than the WIPP grid. Up to 80% of the total variability in radionuclide concentrations across the two grids is attributable to differences between grid nodes. Differences between replicates within a location account for 44-50% of the variability in concentrations of the uranium isotopes, but only 11-17% of the variability in the concentrations of the other radionuclides. Samples having similar abundance of radionuclides were spatially aggregated across the terrain. The activity concentrations of the radionuclides were strongly correlated with the concentrations of Al and Pb, and with the percentages of sand, silt and clay in the soil. Normalizing radionuclide concentrations to the concentration of Al or percent fine particles can help adjust for differences in soil textures among samples and facilitate the detection of gradients or temporal changes in soil concentrations.  相似文献   

6.
This article presents results pertaining to a risk assessment of the potential consequences of a hypothetical accident occurring during the transportation by ship of spent nuclear fuel (SNF) along an Arctic coastline. The findings are based on modelling of potential releases of radionuclides, radionuclide transport and uptake in the marine environment. Modelling work has been done using a revised box model developed at the Norwegian Radiation Protection Authority. Evaluation of the radioecological consequences of a potential accident in the southern part of the Norwegian Current has been made on the basis of calculated collective dose to man, individual doses for the critical group, concentrations of radionuclides in seafood and doses to marine organisms. The results of the calculations indicate a large variability in the investigated parameters above mentioned. On the basis of the calculated parameters the maximum total activity (“accepted accident activity”) in the ship, when the parameters that describe the consequences after the examined potential accident are still in agreement with the recommendations and criterions for protection of the human population and the environment, has been evaluated.  相似文献   

7.
三峡工程移民与社会心理   总被引:1,自引:0,他引:1  
三峡工程移民是关系到三峡工程成败的重要课题。本文从社会心理角度分析探讨了三峡工程对移民心理的作用以及移民的社会心理因素对三峡工程的影响,进而在开发性移民的基础上,提出开发协同式移民的设想,主张不仅应从经济角度考虑,而且还应从社会、心理等多方面研究,以协调人与自然的关系、人与人的关系,达到“天人合一”的境界。  相似文献   

8.
A dynamic model of radionuclide accumulation in fish is developed. In the model, the fish population is represented by a set of discrete age classes. Each age class is characterized by a specific growth rate, diet and activity of metabolic processes. The model describes all known types of size effect in the contamination of fish with radiocaesium. The detailed dynamics of 137Cs accumulation by fish are demonstrated using the results of the model's application to ichtiofauna in a water body which has a high level of contamination with radiocaesium — namely, the cooling pond of the Chernobyl NPP.  相似文献   

9.
The use of experimental settings to observe human behaviour in a controlled environment of incentives, rules and institutions, has been widely used by the behavioural sciences for sometime now, particularly by psychology and economics. In most cases the subjects are college students recruited for one to two hour decision making exercises in which, depending on their choices, they earn cash averaging US$ 20. In such exercises players face a set of feasible actions, rules and incentives (payoffs) involving different forms of social exchange with other people, and that in most cases involve some kind of externalities with incomplete contracts, such as in the case of common-pool resources situations. Depending on the ecological and institutional settings, the resource users face a set of feasible levels of extraction, a set of rules regarding the control or monitoring of individual use, and sometimes ways of imposing material or non-material costs or rewards to those breaking or following the rules. We brought the experimental lab to the field and invited about two hundred users of natural resources in three Colombian rural villages to participate in such decision making exercises and through these and other research instruments we learned about the ways they solve - or fail to - tragedies of the commons with different social institutions. Further, bringing the lab to the field allowed us to explore some of the limitations of existing models about human behaviour and its consequences for designing policies for conserving ecosystems and improving social welfare.  相似文献   

10.
Only two river basins in which the European pearl mussel has survived to date are known in Arkhangelsk oblast. These are the Solza and Kozha basins. The northeastern boundary of the European range of this species passes along the watershed between the basins of the Solza and the Shirshema (the Onega Peninsula) and then along the Onega-Northern Dvina watershed. The population density and the proportion of juveniles widely vary in different parts of the Solza Basin, and, therefore, the previously conclusion concerning the ageing of the population in the Kazanka River (Bolotov and Semushin, 2003) applies only to certain parts of this river. The highest density of the pearl mussel in the Solza Basin is 68 ind./m2. Fish cultivation contributes to the conservation of this pearl mussel population, as the release of Atlantic salmon juveniles ensures reproduction of the mollusk under conditions of regulated river flow.  相似文献   

11.
Nei's genetic distances (Nei, 1972, 1978) between 12 Scotch pine (Pinus sylvestris L.) populations were determined using isozyme analysis. The gradients of these distances along the 1500-km meridional transect in the Transural Region and Northern Turgai from the pre-forest-tundra subzone (the Synya River basin) to the southern steppe (the Naurzumskii forest) were calculated. We discovered that the genetic distance gradients (GDGs) progressively increase in the direction from the northern boundary of the range to the southern boundary of the forest-steppe zone and sharply increase in the insular forests growing in the steppe zone. The results of cluster analysis and Mahalanobis distance gradients with respect to a set of morphological characters of the cones provide evidence that Scotch pine populations of the forest zone share somewhat the same gene pool, whereas the group of Scotch pine populations in the insular forests of Northern Turgai is obviously differentiated phenogenetically from the insular forests of the Tobol region, which grow farther to the north.  相似文献   

12.
During the last decade, the Department of Applied and Medical Physics has been involved in the development of a radiation protection programme. In the framework of this programme, measurements of indoor radon, principally, have been carried out nationwide. Geometric mean radon concentrations of 45 Bq m(-3) in the whole country and 130 Bq m(-3) in the high natural radiation area have been estimated. On the other hand, the so-called MARNA Project is developed into the framework of an agreement subscribed between the Spanish Nuclear Safety Council (CSN) and the National Uranium (ENUSA), the first phase of which has been the elaboration of the Natural Gamma Radiation Map of Spain on the scale of 1:1,000,000 using radiometric data generated in the 30 years of the lifetime of the ancient National Uranium Exploration and Investigation Plan mainly through airborne, carborne, and by foot surveys, within the MARNA Project itself. The lowest averaged dose rate from external gamma radiation (19.3 nGyh(-1)) was found in carbonate bedrock and the highest (87.7 nGyh(-1)) was found in granite and clay bedrock. This paper summarizes the main results obtained from the measurements performed in both projects, with special interest in those concerning the correlation between the data reported in order to conclude about the potential benefit of the MARNA maps in the definition of affected areas in the country.  相似文献   

13.
14.
制定有空间差异的生态补偿标准是构建生态补偿机制的关键和难点。补偿标准的空间差异体现在提供的生态系统服务和付出的成本两个方面。其中,生态补偿保护成本因能准确反映某地关于生态系统保护的工作量和贡献程度而得到广泛关注。本研究针对山区自然因素和人文因素高度空间异质性的特点,以四川省雅安市宝兴县为例,利用GIS技术结合统计资料和实地调研,核算了研究区的保护成本。同时使用面积内插法并从距离、道路、坡度和方向4个方面评价斑块可达性难易程度,进行保护成本空间化研究。旨在为生态补偿标准的制定、生态补偿空间选择以及生态补偿效果评价提供参考和依据。结果显示:1通过考虑距离、道路、坡度和方向,计算得到宝兴县被管护林地的可达性系数,其范围在0—1之间,平均值为0.18,标准差为0.16。22010年,研究区流域生态补偿相关的保护成本为4 590.46万元,其中不同保护对象的投入大小顺序为林地自然保护区水土保持地草地水源保护地。3研究区不同海拔带保护成本及其构成不同,林地保护成本在1 000—4 000 m范围内均较高,这与研究区林地的广泛分布有关;草地保护成本集中在高海拔地区(3 000—4 500 m);而水源保护地保护成本集中在低海拔地区(1 000—2 500 m)。保护成本的核算准确性及空间化精度取决于对当地生态建设与保护措施的掌握程度和资料的收集、获取情况。本研究使用的可达性难易程度来调整保护成本的空间差异,是一种基于地理环境要素空间化思路和尝试。主要考虑距离、道路、坡度和方向4个方面,暂未考虑管护人员的交通工具、视域范围、办事效率等个体因素以及土地利用的限制。  相似文献   

15.
It is shown that the response of rodent populations to acute and chronic irradiation depends on its functional structure, i.e., on specific features of animals with two alternative types of ontogenetic development. Upon acute irradiation, sexually immature young of the year (animals with the second type of ontogeny) are most radioresistant. Exposure to chronic irradiation, as in the zone of the Eastern Ural Radioactive Trace (EURT), leads to an increase in the proportion of mature young of the year (animals with the first type of ontogeny), which are the most radiosensitive part of the population. The abundance and fecundity of mice in the impact zone are consistently higher than in the background zone, which improves the adaptive potential of the population. The role of species ecological specialization and configuration of the contaminated zone in the formation of migrant rodent population is emphasized. It is concluded that a high migration activity allows the pigmy wood mouse (a radiosensitive species) to avoid long-term radiation exposure.  相似文献   

16.
The use of quantitative data for constructing prognostic maps of the dynamics of ecosystem degradation and restoration by nonlinear simulation methods is a topical field of landscape ecology. This method of dynamic cartography is based on fiberwise comparison of data on the state of Chernye Zemli (the Kalmyk Republic, Russia) in different years and the detailed analysis of the period on which the prognosis was based. For this purpose, materials of repeated aerial and satellite photography obtained during a long period (1954–1993) were used. Comparison of maps characterizing the dynamics of Chernye Zemli between 1958 and 1993 allows prognostic electronic maps for the next 10–15 years (with a five-year interval) to be drawn and land prognosis for the next 20–30 years (1998–2023) to be obtained. Deceased  相似文献   

17.
The purpose of this paper is to add to the body of knowledge and understanding of the impact of development and privatization on international environmental protection with the focus on balancing social and economic performance for the affected organizations and communities. More specifically, supported by a database of worldwide, regional, and country studies from 1991 to 2000, it is proposed that the role of development and privatization in environmental administration in the international context has negative as well as positive consequences. Moreover, the negative consequences are often masked or go undetected because the effectiveness of development and privatization is based primarily on economic performance. Thus, to obtain a more accurate and realistic determination of the effectiveness of development and privatization, measures of social as well as economic performance and the overall effect on the natural environment should be considered.  相似文献   

18.
Depth profiles of the specific activities of (14)C and carbon isotopic compositions (Delta(14)C, delta(13)C) in soil organic matter and soil CO(2) in a Japanese larch forest were determined. For investigating the transport of CO(2) in soil, specific activities of (14)C, Delta(14)C and delta(13)C in the organic layer, and atmospheric CO(2) in the same forest area were also determined. The specific activity of (14)C and Delta(14)C in the soil organic matter decreased with the increase in depth of 0-60cm, while that of soil CO(2) did not vary greatly at a soil depth of 13-73cm and was more prevalent than that of atmospheric CO(2). Peaks of specific activities of (14)C appeared at the depth of 0-4cm and Delta(14)C values were positive in the depth range from 0 to 15cm. These results suggest that the present soil at a depth of 0-4cm had been produced from the mid-1950s up until 1963, and the bomb C had reached the depth of 15cm in the objective soil area. The delta(13)C in the soil organic matter increased at the depth of 0-55cm, while that of soil CO(2) collected on 8 November 2004 decreased rapidly at the depth of 0-13cm and only slightly at the depth of 53-73cm. By combining the Delta(14)C and delta(13)C of the respective components and using the Keeling plot approach it was made clear that the entering of atmospheric CO(2) showed a large contribution to soil CO(2) at the depth of 0-13cm and a negligible contribution at the depth of 53-73cm for soil air collected on 8 November 2004. Respiration of live roots was presumed to be the main source of soil CO(2) at the depth of 53-73cm on 8 November 2004.  相似文献   

19.
通过对中国经济发展、资源环境利用以及软实力的分析,对“中国发展”产生的影响作出了基本判断:“中国发展”在国际社会中的整体影响力被误认,我们看到的依然是“中国因素”在不同领域发挥的作用.在经济全球化过程中,资本主义市场经济体系看到的是“中国低廉的劳动力”、“中国宽松的经济制度环境”、“早期没有限制的资源环境滥用”以及“中国广阔的消费市场与人口红利”;在全球或亚洲金融危机中,其他国家看重的是中国多年积累的“外汇”;在全球治理或危机处理中,国际社会期望的是没有话语权的“中国义务和责任”,等等.这些都是“单一因素”在特定领域中产生的“被”作用.中国对国际社会发挥积极和主动性影响作用还需要时间,需要几代人的继续努力.中国曾经是世界上极有影响的大国,中国的崛起是事物发展的正常过程,过多地谈论其影响反映的也许是其影响力的缺乏.  相似文献   

20.
China passed its Plant Variety Protection Act (PVPA) in 1997 which allowed us to do some initial testing of this proposition. We used a unique dataset on the applications of the new Plant Variety Protection (PVP), morphological characteristics, and institutional sources of all the important varieties of rice in three provinces of China to estimate the determinants of plant variety protection applications in China. The evidence suggests that both the government and private research programs are responding to economic and policy incentives and investing in plant variety protection as economists would expect profit maximizing firms to invest. The discussion of the evolution of the seed industry suggested that the combination of the new seed law in 2000 and the new plant variety protection regulation had changed the structure of the seed industry and provided an important incentive to invest in PVPs both by public research institutes and commercial firms. Finally, there is some preliminary evidence that private firms have smaller incentives to develop new varieties than to purchase the new varieties.  相似文献   

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