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261.
上海气象参数与太阳活动和ENSO的关系 总被引:6,自引:0,他引:6
运用2进小波的分解与重构技术分析了太阳活动、厄尔尼诺—南方涛动(ENS0)与上海地区月降水量、月均气压和月均温度序列之间的可能关系。研究结果表明,在不同的时间尺度(频带)上太阳活动和ENS0对上海的月降水量、月均气压和月均温度有不同的影响;在某种程度上ENS0活动对上海月降水量和月均气温的影响强于太阳活动的影响。结果还清楚表明和证实了在不同频带上太阳活动与ENS0活动之间的密切联系。 相似文献
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Revealing life‐history traits by contrasting genetic estimations with predictions of effective population size
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Gili Greenbaum Sharon Renan Alan R. Templeton Amos Bouskila David Saltz Daniel I. Rubenstein Shirli Bar‐David 《Conservation biology》2018,32(4):817-827
Effective population size, a central concept in conservation biology, is now routinely estimated from genetic surveys and can also be theoretically predicted from demographic, life‐history, and mating‐system data. By evaluating the consistency of theoretical predictions with empirically estimated effective size, insights can be gained regarding life‐history characteristics and the relative impact of different life‐history traits on genetic drift. These insights can be used to design and inform management strategies aimed at increasing effective population size. We demonstrated this approach by addressing the conservation of a reintroduced population of Asiatic wild ass (Equus hemionus). We estimated the variance effective size (Nev) from genetic data () and formulated predictions for the impacts on Nev of demography, polygyny, female variance in lifetime reproductive success (RS), and heritability of female RS. By contrasting the genetic estimation with theoretical predictions, we found that polygyny was the strongest factor affecting genetic drift because only when accounting for polygyny were predictions consistent with the genetically measured Nev. The comparison of effective‐size estimation and predictions indicated that 10.6% of the males mated per generation when heritability of female RS was unaccounted for (polygyny responsible for 81% decrease in Nev) and 19.5% mated when female RS was accounted for (polygyny responsible for 67% decrease in Nev). Heritability of female RS also affected Nev; (heritability responsible for 41% decrease in Nev). The low effective size is of concern, and we suggest that management actions focus on factors identified as strongly affecting , namely, increasing the availability of artificial water sources to increase number of dominant males contributing to the gene pool. This approach, evaluating life‐history hypotheses in light of their impact on effective population size, and contrasting predictions with genetic measurements, is a general, applicable strategy that can be used to inform conservation practice. 相似文献
265.
Fengzhi He Simone D. Langhans Christiane Zarfl Roland Wanke Klement Tockner Sonja C. Jähnig 《Conservation biology》2021,35(2):643-653
Megafauna species are intrinsically vulnerable to human impact. Freshwater megafauna (i.e., freshwater animals ≥30 kg, including fishes, mammals, reptiles, and amphibians) are subject to intensive and increasing threats. Thirty-four species are listed as critically endangered on the International Union for Conservation of Nature (IUCN). Red List of Threatened Species, the assessments for which are an important basis for conservation actions but remain incomplete for 49 (24%) freshwater megafauna species. Consequently, the window of opportunity for protecting these species could be missed. Identifying the factors that predispose freshwater megafauna to extinction can help predict their extinction risk and facilitate more effective and proactive conservation actions. Thus, we collated 8 life-history traits for 206 freshwater megafauna species. We used generalized linear mixed models to examine the relationships between extinction risk based on the IUCN Red List categories and the combined effect of multiple traits, as well as the effect of human impact on these relationships for 157 classified species. The most parsimonious model included human impact and traits related to species’ recovery potential including life span, age at maturity, and fecundity. Applying the most parsimonious model to 49 unclassified species predicted that 17 of them are threatened. Accounting for model predictions together with IUCN Red List assessments, 50% of all freshwater megafauna species are considered threatened. The Amazon and Yangtze basins emerged as global diversity hotspots of threatened freshwater megafauna, in addition to existing hotspots, including the Ganges-Brahmaputra and Mekong basins and the Caspian Sea region. Assessment and monitoring of those species predicted to be threatened are needed, especially in the Amazon and Yangtze basins. Investigation of life-history traits and trends in population and distribution, regulation of overexploitation, maintaining river connectivity, implementing protected areas focusing on freshwater ecosystems, and integrated basin management are required to protect threatened freshwater megafauna in diversity hotspots. 相似文献
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Summary. Nickel hyperaccumulator plants contain unusually elevated levels of Ni (>1,000 mg Ni kg−1). The high Ni concentration of hyperaccumulator tissues may affect ecosystem processes such as decomposition, but this has
yet to be studied under field conditions. We used Senecio coronatus Thunb. (Harv.) from two pairs of serpentine sites: one member of each pair contained a hyperaccumulator population and the
other a non-hyperaccumulator population. Our main goal was to determine if leaf Ni status (hyperaccumulator or non-hyperaccumulator)
affected leaf decomposition rate on serpentine sites. We also used a non-serpentine site on which leaves from all four S. coronatus populations were placed to compare decomposition at a single location. Dried leaf fragments were put into fine-mesh (0.1 mm)
nylon decomposition bags and placed on field sites in mid-summer (early February) 2000. Sets of bags were recovered after
1, 3.5, and 8 months, their contents dried and weighed, and the Ni concentration and total Ni content of high-Ni leaves was
measured. For the serpentine sites, there was no significant effect of leaf Ni status or site type on decomposition rates
at 1 and 3.5 months. By 8 months, leaf Ni status and site type significantly influenced decomposition on one pair of sites:
hyperaccumulator leaves decomposed more slowly than non-hyperaccumulator leaves, and leaves of both types decomposed more
slowly on the non-hyperaccumulator site. At the non-serpentine site, the highest-Ni leaves (15,000 mg Ni kg−1) decomposed more slowly than all others, but leaves containing 9,200 mg Ni kg−1 did not decompose more slowly than non-hyperaccumulator leaves. Nickel in decomposing hyperaccumulator leaves was released
rapidly: after 1 month 57–68% of biomass was lost and only 9–28% of original Ni content remained. We conclude that very high
(>10,000 mg Ni kg−1) leaf Ni concentrations may slow decomposition and that Ni is released at high rates that may impact co-occurring litter-
and soil-dwelling organisms. 相似文献
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The environmental degradation of urban rivers and streams in large cities has led to the development of a variety of public policies. In the city of São Paulo, Brazil, a policy for recovering watercourses and valley floors has been developed with the implementation of riverside parks. This represents a new paradigm for the city in terms of its relationship with rivers and streams. This paper presents the results of an exploratory study, which aimed to analyse riverside parks in the city of São Paulo during the last decade. The study analysed the main management difficulties in relation to these types of urban park during their post-implementation stage, assessing their performance in relation to their social and environmental functions. It addressed issues such as the state of the site before and after the implementation of the riverside park, levels of user satisfaction in relation to the state of the watercourse, sports and leisure facilities, green space, security and the way the park is used. The study showed that riverside parks are recognised as elements that improve the quality of public spaces, socially legitimised as public policies. 相似文献
269.
Dilsad Akal Mihriban Yılmaz Civan Gürdal Tuncel Hülya Yavuz Ersan 《Environmental Forensics》2015,16(2):173-185
A total of 34 volatile organic compounds (VOCs) were measured in the indoor of laboratories, offices and classrooms of the Chemical Engineering Department of Hacettepe University in Ankara in 2 week-day passive sampling campaigns. The average concentrations ranged from 0.77 to 265 μg m?3 at the different indoor sites, with the most abundant VOC found to be toluene (119.6 μg m?3), followed by styrene (21.24 μg m?3), 2-ethyltoluene (17.11 μg m?3), n-hexane (10.21 μg m?3) and benzene (9.42 μg m?3). According to the factor analysis, the evaporation of solvents used in the laboratories was found to be the dominant source. 相似文献
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Naomi Millner 《Local Environment》2017,22(6):764-783
In El Salvador a growing permaculture movement attunes small-scale farming activities to principles of ecological observation. The premise is twofold: close-grained appreciation of already-interacting biophysical processes allows for the design of complementary social and agricultural systems requiring minimum energy inputs. Secondly, the insistence on campesino smallholders as actors in the design of sustainable food systems directly addresses decades of “top-down” developmental interventions, from Green Revolution experiments in the 1960s and 1970s to international food security programmes in the 1990s. Permaculture connects food insecurity to the delegitimisation of smallholder innovation and insists that, through sharing simple techniques, campesino farmers can contribute towards future-oriented questions of environmental sustainability. This repositioning is brought about through the mobilisation of pedagogical techniques that legitimise the experiences and expertise of small-scale farmers, while standardising experimental methods for testing, evaluating and sharing agroecological practices. Like food sovereignty and food justice movements, Salvadoran permaculture links hunger with longer histories of (uneven) capital accumulation and dispossession and renders campesino farmers its protagonists. By modelling a form of expertise premised in intimate involvement with specific environments, permaculture goes still further, seeking to dislodge a pervasive knowledge politics that situates some as knowers and innovators, and others as passive recipients. This grounds human rights in an ethos of caring for the “more-than-human” world and places emphasis on a corollary right as part of food justice, increasingly being demanded “from below”: the right to know. 相似文献