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991.
The diet of great apes consists of several hundred plant species. The factors determining diet differences have been examined between populations but not within a population, probably due to the confounding effect of seasonal fluctuations on fruit availability. In Sumatran orangutans (Pongo abelii), fruit availability appears to be sufficiently high year round to have little influence on diet composition, which in turn allows for addressing this question. We examined the diet of eight adult female orangutans at Ketambe, Sumatra, and investigated whether fig and non-fig fruit availability, association time, and/or home range measures influenced dietary overlap between female dyads. Between most pairs, females’ diets were different: 16 out of 23 pairs had a significantly low diet species overlap. Only fig diet overlap was influenced (negatively) by the availability of non-fig fruit. Association time only influenced (positively) fig diet overlap. Hence, orangutans gathered in fig trees when non-fig fruit availability was low. Home range measures did not influence overall diet overlap. To our knowledge, this is the first study showing that, while controlling for confounding factors, individuals with similar energetic requirements, from the same population and sharing the same area, make different dietary choices relatively to their preferred (non-fig) fruit constituting the majority of their diet. Social transmission, with putative matrilineal diet traditions, suitably explains these results. We discuss the implications of the findings for orangutan conservation, namely on reintroduction and the felling of fig trees.  相似文献   
992.
For the protection of early and summer cauliflower and brussels sprouts crops against root fly, the insecticide chlorpyrifos was applied at planting onto soil around the stem of the plant, or in the planting line. In the soil, chlorpyrifos (1) was transformed into the insecticide metabolites oxon, 0,0‐diethyl‐0‐(3,5,6‐tri‐chloro‐2‐pyridinyl) phosphate (2), and 3,5,6‐trichloro‐2‐pyridinol (3). The soil half life time of chlorpyrifos could be 2.8 times greater (42 days relative to 15 days) when the field history as to cauliflower monoculture and insecticide treatments was short (1 year), than when it was long (8 years). Rains and season also had cumulative effects on the chlorpyrifos soil half life times. In the leaves of cabbage, chlorpyrifos and compound 3 were observed at concentrations which were higher, especially when their soil concentrations were high. Chlorpyrifos and compounds 2 and 3 however were not detected in the “flower” of cauliflower, nor in the brussels sprouts itself, the limit of sensitivity being 0.02 ppm of fresh weight.  相似文献   
993.
Assessing sediment quality requires sampling designs which address variability. Often however, only one sample or composited sample is collected at a sample site. Existing studies on sediment variability or sampling strategies primarily concern lake or marine sediments. Two rivers and one canal were sampled to assess sediment variability. Further, it was determined if sediment contamination in running water could be predicted by using visual criteria and/or knowledge of the presence of depositional and erosion areas. Metal concentrations and sediment characteristics were measured in different visually distinct areas of the river. At all sample sites the coefficient of variance was relatively high for most sediment characteristics (1.4‐ > 100%) and metal levels (15.3–63.6%). In one river the majority of sediment characteristics variation was between two sediment types and detected by visually distinct differences. Significant differences in cadmium and zinc concentrations were also detected. Contrary to what was expected, cadmium, and zinc levels were highest in the coarse fraction. No differences were found in the second river. In the canal a greater concentration of fine grained sediments and metals were found in the deep areas. It was not possible to predict sediment areas with the highest levels of metal contamination using visual criteria or knowledge of the erosion and sedimentation pattern of the river.  相似文献   
994.
SUMMARY

A scheme in which psychological factors are considered in effective forest management planning is proposed. A central role is played by human carrying capacity, the resilience of people to deal with the consequences of environmental degradation. Stress and marginalization are taken as indicators of human carrying capacity. A study in Côte d'Ivoire is described in which psychological stress and marginalization were studied in individuals from environments which show different degrees of degradation. Three related hypotheses are proposed: first that individuals living in or near a degrading forest are more stressed and marginalized than individuals in a reference group living in Abidjan; second that people living near the forest with the most sustained and severe degradation would be more stressed and marginalized; finally, that members of autochthonous cultural groups show higher stress and marginalization levels than members of migrant groups. The results of our study showed that people living near the degraded forest were more stressed but not marginalized unless the degradation was severe and sustained. Females were more stressed than males and members of both sexes from autochthonous cultural groups were more prone to stress and marginalization than members of migrant groups.  相似文献   
995.
In order to examine the role of position in the tidal range on biomass production and nutrient pools in Spartina alterniflora in an Argentinian estuary, we estimated productivity, the concentration of C, N and P in tissues and pools (concentration×biomass) of these elements in low (LM) and high (HM) zones. Aboveground biomass of S. alterniflora was higher in HM than in LM. Aboveground primary productivity was 106 and 439 g dry wt m?2 year?1 in LM and HM, respectively. Belowground biomass was similar in LM and HM. Belowground primary productivity was 526 and 744 g dry wt m?2 year?1 for LM and HM, respectively. Nutrient pools were higher in HM than in LM. Biomass and productivity values were low, which makes nutrient pools low. The lower values of the parameters analysed in LM than in HM indicate that position in the tidal range is an important factor in this system, possibly due to the effect of flooding. Moreover, this pattern is opposite to the general one observed in the northern hemisphere, meaning that studying marshes from different environments is worth doing. Because pools were higher in HM, this zone would be more important for nutrient input to the estuary.  相似文献   
996.
IntroductionInsomespecialgeomorphic,geological,lithogeochemicalandhydrogeochemicalenvironment,thegroundwaterandsoilinsomeareas?..  相似文献   
997.
纳米颗粒的种间毒性关系尚无明确结论,因此很难判断纳米颗粒对未进行毒性测试的物种的风险如何。本文作者将5种水蚤(Daphnia magna, Daphnia pulex, Daphnia galeata, Ceriodaphnia dubia, Chydorus sphaericus)暴露于4种不同粒径的纳米铜颗粒(CuNPs)和1种亚微米铜颗粒的悬浊液中,考察物种的形态特征与CuNPs急性毒性的关系。结果显示,杆状的CuNPs比球状的CuNPs毒性更低。纳米铜颗粒与溶出铜离子均对CuNPs的毒性有贡献,其中,当新生蚤的体长、体表面积和身体体积更小时,5种悬浊液中颗粒的毒性更大。5种蚤的身体体积与5种CuNPs的毒性显著相关(radj2>0.51, p < 0.001),78-nm CuNPs与蚤身体体积的相关性最好 (radj2?=?0.95, p < 0.001)。这个研究可以为纳米颗粒对有相似外形特征的物种进行毒性种间外推提供线索。
精选自Lan Song, Martina G. Vijver, Geert R. de Snoo and Willie J.G.M. Peijnenburg. Assessing toxicity of copper nanoparticles across five cladoceran species. Environmental Toxicology and Chemistry: Volume 34, Issue 8, pages 1744–1750, August 2015. DOI: 10.1002/etc.3000
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3000/full  相似文献   
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1000.
Water allocation systems are challenged by hydrologic droughts, which reduce available water supplies and can adversely affect human and environmental systems. To address this problem, drought management mechanisms have been instituted in jurisdictions around the world. Historically, these mechanisms have involved a crisis management or reactive approach. An important trend during the past decade in places such as the United States has been a shift to a more proactive approach, emphasizing drought preparedness and local involvement. Unfortunately, local capacity for drought planning is highly variable, with some local governments and organizations proving to be more capable than others of taking on new responsibilities. This paper reports on a study of drought planning and water allocation in the State of Minnesota. Factors facilitating and constraining local capacity for drought planning were identified using in-depth key informant interviews with state officials and members of two small Minnesota cities, combined with an analysis of pertinent documentation. A key factor contributing to the effectiveness of Minnesota's system is a water allocation system with explicit priorities during shortages, and provisions for restrictions. At the same time, the requirement that water suppliers create Public Water Supply Emergency Conservation Plans (PWSECP) clarifies the roles and responsibilities of key local actors. Unfortunately, the research revealed that mandated PWSECP are not always implemented, and that awareness of drought and drought planning measures in general may be poor at the local level. From the perspective of the two cities evaluated, factors that contributed to local capacity included sound financial and human resources, and (in some cases) effective vertical and horizontal linkages. This analysis of experiences in Minnesota highlights problems that can occur when senior governments establish policy frameworks that increase responsibilities at the local level without also addressing local capacity.  相似文献   
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