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521.
In 1974, Junge postulated a relationship between variability of concentrations of gases in air at remote locations and their atmospheric residence time, and this Junge relationship has subsequently been observed empirically for a range of trace gases. Here, we analyze two previously-published datasets of concentrations of cyclic volatile methyl siloxanes (cVMS) in air and find Junge relationships in both. The first dataset is a time series of concentrations of decamethylcyclopentasiloxane (D5) measured between January and June, 2009 at a rural site in southern Sweden that shows a Junge relationship in the temporal variability of the measurements. The second dataset consists of measurements of hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4) and D5 made simultaneously at 12 sites in the Global Atmospheric Passive Sampling (GAPS) network that shows a Junge relationship in the spatial variability of the three cVMS congeners. We use the Junge relationship for the GAPS dataset to estimate atmospheric lifetimes of dodecamethylcyclohexasiloxane (D6), 8:2–fluorotelomer alcohol and trichlorinated biphenyls that are within a factor of 3 of estimates based on degradation rate constants for reaction with hydroxyl radical determined in laboratory studies. 相似文献
522.
Schoffer Jorge Tomás Antilén Mónica Neaman Alexander Díaz María Francisca de la Fuente Luz María Urdiales Cristian Ginocchio Rosanna 《Environmental science and pollution research international》2021,28(43):60913-60922
Environmental Science and Pollution Research - This study assessed the capacity of leaf litters to adsorb copper ions applied as a copper-based pesticide. Leaf litters of two fruit tree species... 相似文献
523.
Jonathan Salerno Karen Bailey Andrea E. Gaughan Forrest R. Stevens Tom Hilton Lin Cassidy Michael D. Drake Narcisa G. Pricope Joel Hartter 《Conservation biology》2020,34(4):891-902
Interactions between humans and wildlife resulting in negative impacts are among the most pressing conservation challenges globally. In regions of smallholder livestock and crop production, interactions with wildlife can compromise human well-being and motivate negative sentiment and retaliation toward wildlife, undermining conservation goals. Although impacts may be unavoidable when human and wildlife land use overlap, scant large-scale human data exist quantifying the direct costs of wildlife to livelihoods. In a landscape of global importance for wildlife conservation in southern Africa, we quantified costs for people living with wildlife through a fundamental measure of human well-being, food security, and we tested whether existing livelihood strategies buffer certain households against crop depredation by wildlife, predominantly elephants. To do this, we estimated Bayesian multilevel statistical models based on multicounty household data (n = 711) and interpreted model results in the context of spatial data from participatory land-use mapping. Reported crop depredation by wildlife was widespread. Over half of the sample households were affected and household food security was reduced significantly (odds ratio 0.37 [0.22, 0.63]). The most food insecure households relied on gathered food sources and welfare programs. In the event of crop depredation by wildlife, these 2 livelihood sources buffered or reduced harmful effects of depredation. The presence of buffering strategies suggests a targeted compensation strategy could benefit the region's most vulnerable people. Such strategies should be combined with dynamic and spatially explicit land-use planning that may reduce the frequency of negative human–wildlife impacts. Quantifying and mitigating the human costs from wildlife are necessary steps in working toward human–wildlife coexistence. 相似文献
524.
S. A. Norton I. J. Fernandez J. S. Kahl L. E. Rustad Tomás Navrátil H. Almquist 《Environmental monitoring and assessment》2010,171(1-4):3-21
The Bear Brook Watershed in Maine (BBWM), USA is a paired watershed study with chemical manipulation of one watershed (West Bear = WB) while the other watershed (East Bear = EB) serves as a reference. Characterization of hydrology and chemical fluxes occurred in 1987–1989 and demonstrated the similarity of the ca. 10 ha adjacent forested watersheds. From 1989–2010, we have added 1,800 eq (NH4)2SO4 ha???1 y???1 to WB. EB runoff has slowly acidified even as atmospheric deposition of SO $_{4}^{2-}$ has declined. EB acidification included decreasing pH, base cation concentrations, and alkalinity, and increasing inorganic Al concentration, as SO $_{4}^{2-}$ declined. Organic Al increased. WB has acidified more rapidly, including a 6-year period of increasing leaching of base cations, followed by a long-term decline of base cations, although still elevated over pretreatment values, as base saturation declined in the soils. Sulfate in WB has not increased to a new steady state because of increased anion adsorption accompanying soil acidification. Dissolved Al has increased dramatically in WB; increased export of particulate Al and P has accompanied the acidification in both watersheds, WB more than EB. Nitrogen retention in EB increased after 3 years of study, as did many watersheds in the northeastern USA. Nitrogen retention in WB still remains at over 80%, in spite of 20+ years of N addition. The 20-year chemical treatment with continuous measurements of critical variables in both watersheds has enabled the identification of decadal-scale processes, including ecosystem response to declining SO $_{4}^{-2}$ in ambient precipitation in EB and evolving mechanisms of treatment response in WB. The study has demonstrated soil mechanisms buffering pH, declines in soil base saturation, altered P biogeochemistry, unexpected mechanisms of storage of S, and continuous high retention of treatment N. 相似文献
525.
Fabrizia Ratto Tom D. Breeze Lorna J. Cole Michael P. D. Garratt David Kleijn Bill Kunin Denis Michez Rory O'Connor Jeff Ollerton Robert J. Paxton Guy M. Poppy Simon G. Potts Deepa Senapathi Rosalind Shaw Lynn V. Dicks Kelvin S.-H. Peh 《Conservation biology》2022,36(4):e13886
Pollinator declines have prompted efforts to assess how land-use change affects insect pollinators and pollination services in agricultural landscapes. Yet many tools to measure insect pollination services require substantial landscape-scale data and technical expertise. In expert workshops, 3 straightforward methods (desk-based method, field survey, and empirical manipulation with exclusion experiments) for rapid insect pollination assessment at site scale were developed to provide an adaptable framework that is accessible to nonspecialist with limited resources. These methods were designed for TESSA (Toolkit for Ecosystem Service Site-Based Assessment) and allow comparative assessment of pollination services at a site of conservation interest and in its most plausible alternative state (e.g., converted to agricultural land). We applied the methods at a nature reserve in the United Kingdom to estimate the value of insect pollination services provided by the reserve. The economic value of pollination services provided by the reserve ranged from US$6163 to US$11,546/year. The conversion of the reserve to arable land would provide no insect pollination services and a net annual benefit from insect-pollinated crop production of approximately $1542/year (US$24∙ha–1∙year–1). The methods had wide applicability and were readily adapted to different insect-pollinated crops: rape (Brassica napus) and beans (Vicia faba) crops. All methods were rapidly employed under a low budget. The relatively less robust methods that required fewer resources yielded higher estimates of annual insect pollination benefit. 相似文献
526.
Measuring diversity: the importance of species similarity 总被引:4,自引:0,他引:4
Realistic measures of biodiversity should reflect not only the relative abundances of species, but also the differences between them. We present a natural family of diversity measures taking both factors into account. This is not just another addition to the already long list of diversity indices. Instead, a single formula subsumes many of the most popular indices, including Shannon's, Simpson's, species richness, and Rao's quadratic entropy. These popular indices can then be used and understood in a unified way, and the relationships between them are made plain. The new measures are, moreover, effective numbers, so that percentage changes and ratio comparisons of diversity value are meaningful. We advocate the use of diversity profiles, which provide a faithful graphical representation of the shape of a community; they show how the perceived diversity changes as the emphasis shifts from rare to common species. Communities can usefully be compared by comparing their diversity profiles. We show by example that this is a far more subtle method than any relying on a single statistic. Some ecologists view diversity indices with suspicion, questioning whether they are biologically meaningful. By dropping the naive assumption that distinct species have nothing in common, working with effective numbers, and using diversity profiles, we arrive at a system of diversity measurement that should lay much of this suspicion to rest. 相似文献
527.
Wim Bonckaert Adam Tofilski Fabio S. Nascimento Johan Billen Francis L. W. Ratnieks Tom Wenseleers 《Behavioral ecology and sociobiology》2011,65(4):633-640
In insect societies, workers often try to challenge the reproductive monopoly of the queen by laying their own eggs. Successful worker reproduction, however, is frequently prevented by queen policing or worker policing, whereby either the mother queen or non-reproductive workers selectively kill worker-laid eggs. Recently, a third mechanism—“selfish” worker policing—has also been described in which the workers selectively police worker-laid eggs but also lay eggs themselves. Here, we present results from the monogynous wasp Dolichovespula norwegica, which show that all three kinds of policing—queen policing, worker policing and “selfish” worker policing—co-occur. The net effect of these three kinds of policing collectively favoured the queen’s reproduction, as within 1 day 44% of the worker-laid eggs versus only 8% of the queen-laid eggs were eaten. Of the worker-laid eggs that were killed by workers, approximately two thirds were eaten by the reproductive workers even though these made up only a small proportion, 8%, of the work force. This means that policing workers obtained both direct fitness benefits as well as indirect (inclusive) fitness. In addition, we show that worker policing was carried out by a limited, specialised set of workers that was estimated to constitute approximately one quarter of the whole colony and of which 66% were non-reproductive. 相似文献
528.
Daniel Kozák Marek Svitok Veronika Zemlerová Martin Mikoláš Thibault Lachat Laurent Larrieu Yoan Paillet Arne Buechling Radek Bače William S. Keeton Lucie Vítková Krešimir Begovič Vojtěch Čada Martin Dušátko Matej Ferenčík Michal Frankovič Rhiannon Gloor Jeňýk Hofmeister Pavel Janda Ondrej Kameniar Tomáš Kníř Linda Majdanová Marek Mejstřík Jakob Pavlin Dheeraj Ralhan Ruffy Rodrigo Catalin-Constantin Roibu Michal Synek Ondřej Vostarek Miroslav Svoboda 《Conservation biology》2023,37(3):e14066
Protecting structural features, such as tree-related microhabitats (TreMs), is a cost-effective tool crucial for biodiversity conservation applicable to large forested landscapes. Although the development of TreMs is influenced by tree diameter, species, and vitality, the relationships between tree age and TreM profile remain poorly understood. Using a tree-ring-based approach and a large data set of 8038 trees, we modeled the effects of tree age, diameter, and site characteristics on TreM richness and occurrence across some of the most intact primary temperate forests in Europe, including mixed beech and spruce forests. We observed an overall increase in TreM richness on old and large trees in both forest types. The occurrence of specific TreM groups was variably related to tree age and diameter, but some TreM groups (e.g., epiphytes) had a stronger positive relationship with tree species and elevation. Although many TreM groups were positively associated with tree age and diameter, only two TreM groups in spruce stands reacted exclusively to tree age (insect galleries and exposed sapwood) without responding to diameter. Thus, the retention of trees for conservation purposes based on tree diameter appears to be a generally feasible approach with a rather low risk of underrepresentation of TreMs. Because greater tree age and diameter positively affected TreM development, placing a greater emphasis on conserving large trees and allowing them to reach older ages, for example, through the establishment of conservation reserves, would better maintain the continuity of TreM resource and associated biodiversity. However, this approach may be difficult due to the widespread intensification of forest management and global climate change. 相似文献
529.
The need to look beyond the production and provision of relief seed: experiences from southern Sudan
Free distribution of seeds in selected areas of southern Sudan has been widespread as a way of increasing food security. Field research in areas targeted for seed relief found that farmer seed systems continue to meet the crop and varietal needs of farmers even following the 1998 famine. Donor investments in seed multiplication of improved sorghum have not been sustained due to a lack of effective demand for the improved seed beyond that created by the relief agencies. The article argues that rather than imposing outside solutions, whether through seed provisioning or seed production enterprises, greater attention needs to be given to building on the strengths of existing farmer systems and designing interventions to alleviate the weaknesses. The case is made to support dynamically the process of farmer experimentation through the informed introduction of new crops and varieties that can potentially reinforce the strength and diversity of local cropping systems. 相似文献
530.
Louis V. Verchot Meine Van Noordwijk Serigne Kandji Tom Tomich Chin Ong Alain Albrecht Jens Mackensen Cynthia Bantilan K. V. Anupama Cheryl Palm 《Mitigation and Adaptation Strategies for Global Change》2007,12(5):901-918
Agriculture is the human enterprise that is most vulnerable to climate change. Tropical agriculture, particularly subsistence
agriculture is particularly vulnerable, as smallholder farmers do not have adequate resources to adapt to climate change.
While agroforestry may play a significant role in mitigating the atmospheric accumulation of greenhouse gases (GHG), it also
has a role to play in helping smallholder farmers adapt to climate change. In this paper, we examine data on the mitigation
potential of agroforestry in the humid and sub-humid tropics. We then present the scientific evidence that leads to the expectation
that agroforestry also has an important role in climate change adaptation, particularly for small holder farmers. We conclude
with priority research questions that need to be answered concerning the role of agroforestry in both mitigation and adaptation
to climate change. 相似文献