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131.
In this paper we synthesise the findings from the papers in this special issue on Organising productive science-policy interactions for sustainable coastal management. Lessons from the Wadden Sea. We first briefly discuss some relevant theoretical debates, and then present our main insights and lessons from the empirical evidence reported in the papers. We conclude the paper with suggestions for further research.  相似文献   
132.
Watson, Tara K., Dorothy Q. Kellogg, Kelly Addy, Arthur J. Gold, Mark H. Stolt, Sean W. Donohue, and Peter M. Groffman, 2010. Groundwater Denitrification Capacity of Riparian Zones in Suburban and Agricultural Watersheds. Journal of the American Water Resources Association (JAWRA) 46(2):237-245. DOI: 10.1111/j.1752-1688.2010.00418.x Abstract: We evaluated the relationship of dominant watershed land use to the structure and nitrogen (N) sink function of riparian zones. We focused on groundwater denitrification capacity, water table dynamics, and the presence and pattern of organically enriched deposits. We used the push-pull method (measurement of 15N-enriched denitrification gases derived from an introduced groundwater plume of 15N-enriched nitrate) to evaluate groundwater denitrification capacity on nine forested wetland riparian sites developed in alluvial or outwash parent materials in southern New England. Three replicate sites were located in each of the three watershed types, those with substantial (1) irrigated agriculture, (2) suburban development, and (3) forest. Soil morphology and water table dynamics were assessed at each site. We found significantly lower mean annual water tables at sites within watersheds with substantial irrigated agriculture or suburban development than forested watersheds. Water table dynamics were more variable at sites within suburban watersheds, especially during the summer. Groundwater denitrification capacity was significantly greater at sites within forested watersheds than in watersheds with substantial irrigated agriculture. Because of the high degree of variability observed in riparian sites within suburban watersheds, groundwater denitrification capacity was not significantly different from either forested or agricultural watersheds. The highly variable patterns of organically enriched deposits and water tables at sites within suburban watersheds suggests that depositional events are irregular, limiting the predictability of groundwater N dynamics in these riparian zones. The variability of riparian N removal in watersheds with extensive suburbia or irrigated agriculture argues for N management strategies emphasizing effective N source controls in these settings.  相似文献   
133.
Least flycatchers (Empidonax minimus) and American redstarts (Setophaga ruticilla) overlap in the use of food resources on their breeding grounds, promoting high levels of interspecific aggression by the socially dominant flycatcher. We examined the role of song in this interspecific aggression by using repeated-measures-designed playback experiments and observational data on induced aggressive interactions. Flycatchers were more likely to approach the speaker during presentation of redstart song than during intervals of no song or presentation of control song. Approach was close enough to enable visual contact with a singing redstart. In contrast, redstarts made significantly fewer flights following presentation of flycatcher song, when risk of flycatcher attack may be greatest. Reducing the number of flights likely reduces the risk of flycatcher attack on the redstart, as flycatchers do not attack stationary redstart models and are apparently dependent on cues from redstart flight for visual heterospecific recognition. Flycatcher-specific responses of redstarts and marked differences in song morphology rule out misdirected intraspecific aggression as a proximate or ultimate cause of interspecific response to song. Results indicate that song is an important component in aggressive interactions between these two species, and reflect the dominant role of the flycatcher in such interactions. Our results also illustrate the capacity for interspecific interference competition to influence behavior and heterospecific song recognition in two distant avian taxa. Received: 10 January 1995/Accepted after revision: 8 June 1996  相似文献   
134.
肠道微生物群落在与其宿主长期协同进化过程中会形成大量的宿主-肠道微生物互作基因,这些互作基因具有一定的宿主肠道微生物特异性,利用其设计分子标记能有效识别粪便污染源.本研究首次利用竞争性杂交的方法富集猪粪便特异性基因,从中筛选出具有猪粪便特异性的基因片段,以此设计引物并建立相应的PCR检测方法,并对采集样进行应用调查.竞争性杂交富集的猪粪便特异性基因文库以拟杆菌群(Bacteroidetes)(43.2%)和梭状杆菌群(Clostridia)(19.5%)相似序列为主,其蛋白功能主要分为3大类:与信息贮存与加工有关(7.6%),与细胞加工及信息传导有关(12.8%)以及与代谢有关(22.0%).进一步针对功能蛋白序列筛选宿主粪便特异性分子标记.分析表明序列3-53-2对应引物可作为猪粪便污染的特异性分子标记,针对其建立的常规PCR方法对粪便DNA的检出限可低至0.01 ng·μL-1,且对实际样品具有较高的应用灵敏性(97%)和特异性.进一步对可能受污染水样进行猪粪便污染特异性检测,结果显示不同地区的阳性检出率高达75%~100%,证明了此方法的有效性,可为研究微生物示踪技术在非点源污染方面的应用提供一定的基础数据.  相似文献   
135.
This research studied possible benefits of indoor plants on attention capacity in a controlled laboratory experiment. Participants were 34 students randomly assigned to one of two conditions: an office setting with four indoor plants, both flowering and foliage, or the same setting without plants. Attention capacity was assessed three times, i.e. immediately after entering the laboratory, after performing a demanding cognitive task, and after a five-minute break. Attention capacity was measured using a reading span test, a dual processing task known to tap the central executive function of attention. Participants in the plant condition improved their performance from time one to two, whereas this was not the case in the no-plant condition. Neither group improved performance from time two to three. The results are discussed in the context of Attention Restoration Theory and alternative explanations.  相似文献   
136.
Cyclic population dynamics of forest insects with periods of more than two generations have been discussed in relation to a variety of extrinsic and intrinsic forces. In the present study, we employed the selection pressure of density dependent competitive interactions according to Witting's equations (Witting, 2000) as driver for a discrete spatiotemporal model of the green oak leaf roller (Tortrix viridana). The model was successfully parameterised to rebuild the cyclic population dynamics of an empirical data set of a 30-year leaf roller monitoring in Russia. Our analysis focussed on the role of herbivore mortality and host plant food quality, which have a significant effect on T. viridana population dynamics. An additional egg or larvae mortality lowers population density and can lead to selection pressures that favour individuals with higher growth rate. This increased population growth rate can not only compensate the additional mortality, but also can lead to higher average moth abundances in subsequent generations. Furthermore, we analysed the effect of inter- and intraspecific variation in host plant quality on herbivore population dynamics and the spatial distribution of abundance and defoliation patterns. We found significant effects of the qualitative composition of a trees neighbourhood on the herbivore population of the respective tree. Also, the patchy damage patterns observable in reality have been reproduced by the present model. The applicability of the model approach and the putative genetic processes underlying Witting's model are discussed.  相似文献   
137.
The analysis of palaeoenvironmental archives—sediments, archaeological remains, tree-rings, documents and instrumental records—is presented as a key element in the global scientific endeavour aimed at understanding human–environment interactions at the present day and in the future. The paper explains the need for the focus on palaeoenvironmental studies as a means of ‘learning from the past’, and presents the rationale and structure of the IGBP-PAGES Focus 5 programme ‘Past Ecosystem Processes and Human–Environment Interactions’. The past, as described through palaeoenvironmental studies, can yield information about pre-impact states, trajectories of recent change, causation, complex system behaviour, and provide the basis for developing and testing simulation models. Learning from the past in each of these epistemological categories is exemplified with published case-studies.  相似文献   
138.
Abstract:  Road disturbances can influence wildlife health by spreading disease agents and hosts or by generating environmental conditions that sustain these agent and host populations. I evaluated field patterns of trematode infections in snails inhabiting ponds at varying distances from the Dalton Highway, a wilderness road that intersects northern Alaska. I also assessed the relationships between trematode infections and snail densities and six environmental variables: calcium concentration, aquatic vegetative cover, canopy cover, temperature, pond size, and community structure. Presence of trematode infections and snail density were negatively correlated with distance from the highway. Of the pond characteristics measured, only calcium concentration and vegetation density declined with distance from road. However, neither variable was positively associated with snail density or trematode presence. One potential explanation for observed patterns is that vehicles, road maintenance, or vertebrate vectors attracted to the highway facilitate colonization of snails or trematodes. Emerging disease threats to biological diversity in northern ecosystems highlight the importance of understanding how roads affect disease transmission.  相似文献   
139.
In the Piedmont of North Carolina, a traditionally water‐rich region, reservoirs that serve over 1 million people are under increasing pressure due to naturally occurring droughts and increasing land development. Innovative development approaches aim to maintain hydrologic conditions of the undisturbed landscape, but are based on insufficient target information. This study uses the hydrologic landscape concept to evaluate reference hydrology in small headwater catchments surrounding Falls Lake, a reservoir serving Raleigh and the greater Triangle area. Researchers collected one year of detailed data on water balance components, including precipitation, evapotranspiration, streamflow, and shallow subsurface storage from two headwater catchments representative of two hydrologic landscapes defined by differences in soils and topographic characteristics. The two catchments are similar in size and lie within the same physiographic region, and during the study period they showed similar water balances of 26‐30% Q, ?4 to 5% ΔS, 59‐65% evapotranspiration, and 9‐10% G. However, the steeper, more elevated catchment exhibited perennial streamflow and nongrowing season runoff ratios (Q/P) of 33%, whereas the flat, low‐lying stream was drier during the growing season and exhibited Q/P ratios of 52% during the nongrowing season. A hydrologic landscape defined by topography and soil characteristics helps characterize local‐scale reference hydrology and may contribute to better land management decisions.  相似文献   
140.
基于2015—2020年成都市国控环境监测站点逐时大气污染物监测数据,将其分为3类站点(城区、交通、背景站点),研究不同季节、不同污染水平下,各类站点细颗粒物(PM2.5)和臭氧(O3)复合污染特征及相互作用.结果表明:①成都各类站点的PM2.5超标天数和PM2.5年平均浓度总体呈下降趋势,背景站点浓度明显小于城区站点和交通站点;O3年际变化趋势呈波动性,且交通站点和背景站点的变化波动强于城区站点.②各类站点PM2.5与O3相关性在O3污染期(4—8月)和PM2.5污染期(11—次年1月)均存在显著差异,且二者在不同季节甚至呈现相反的相关性,总体趋势为夏季PM2.5-O3的相关性趋于正相关,冬季趋于负相关.③O3污染期,各类站点二次PM2.5的浓度和贡献率随光化学水平的升高而增加,而一次PM2.5日变化幅度差异不大,表现出明显的O3和PM2.5协同增长现象.④PM2.5污染期,PM2.5与O3之间并不是简单的线性关系,不同PM2.5污染程度下,各类站点O3浓度变化率昼夜波动趋势基本相同,均在12:00—13:00达到峰值,在18:00达到谷值;且随着PM2.5浓度的增加,O3浓度变化率峰值/谷值波动范围亦随之增加.  相似文献   
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