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Differential effects of two dominant plant species on community structure and invasibility in an old-field ecosystem

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Journal of Plant Ecology 2011年第3期4卷 123-131页

作者： Lara Souza jake f.weltzin Nathan J.Sanders Department of Ecology and Evolutionary Biology University of Tennessee1416 Circle DriveKnoxvilleTN 37996USA USA National Phenology Network National Coordinating Office1955 East 6th StreetTucsonAZ 85719USA

Aims In this study,we examined the effects of Solidago altissima(hereafter Solidago)and two species in the genus Verbesina,Verbesina virginica and Verbesina occidentalis(hereafter Verbesina),on the structure of an old-field plant community and establishment by an invasive plant species,Lespedeza cuneata(hereafter Lespedeza).Methods We removed Solidago,Verbesina and both Solidago and Verbesina from 4m^(-2)plots in an intact old-field community during two growing *** then quantified the effects of these removals on richness,evenness,diversity and composition of the subdominant plant *** also measured the total aboveground biomass and the aboveground biomass of the subdominant *** assess how these removals affected establishment by Lespedeza,we planted 20 seeds in each plot and tracked seedling emergence and survival for one growing *** findings Subdominant community evenness and Shannon diversity were higher in plots from which Solidago and Verbesina were removed relative to control ***,there were no effects of dominant species removal on species richness or composition of the subdominant *** aboveground biomass was not affected by dominant species removal,suggesting that the community of subdominant species exhibited *** fact,subdominant community biomass was greater when Solidago,but not Verbesina,was *** availability was also greater in plots where Solidago was removed relative to control plots throughout the growing *** addition,removal of dominant species,in particular Solidago,indirectly reduced the emergence,but not survival,of Lespedeza seedlings by directly promoting subdominant community *** together,our results suggest that dominant old-field plant species affect subdominant community structure and indirectly promote establishment by Lespedeza.

关键词： compensation establishment invasive Lespedeza cuneata Solidago Verbesina

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Temperature Responses to Infrared-Loading and Water Table Manipulations in Peatland Mesocosms

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Journal of Integrative Plant Biology 2008年第11期50卷 1484-1496页

作者： Jiquan Chen Scott Bridgham Jason Keller John Pastor Asko Noormets jake f.weltzin Department of Environmental Sciences University of Toledo Center for Ecology and Evolutionary Biology University of Oregon Smithsonian Environmental Research Center Department of Biological Sciences University of Minnesota National Phenology Network

We initiated a multi-factor global change experiment to explore the effects of infrared heat loading （HT） and water table level （WL） treatment on soil temperature （T） in bog and fen peatland mesocosms. We found that the temperature varied highly by year, month, peatland type, soil depth, HT and WL manipulations. The highest effect of HT on the temperature at 25 cm depth was found in June for the bog mesocosms （3.34-4.27 ℃） but in May for the fen mesocosms （2.32-4.33 ℃） over the 2-year study period. The effects of WL in the bog mesocosms were only found between August and January, with the wet mesocosms warmer than the dry mesocosms by 0.48-2.03 ℃ over the 2-year study period. In contrast, wetter fen mesocosms were generally cooler by 0.16-3.87℃. Seasonal changes of temperatures elevated by the HT also varied by depth and ecosystem type, with temperature differences at 5 cm and 10 cm depth showing smaller seasonal fluctuations than those at 25 cm and 40 cm in the bog mesocosms. However, increased HT did not always lead to warmer soil, especially in the fen mesocosms. Both HT and WL manipulations have also changed the length of the non-frozen season.

关键词： global change infrared mesocosm peatlands warming experiment water table.

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CO_(2)enrichment accelerates successional development of an understory plant community

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Journal of Plant Ecology 2010年第1期3卷 33-39页

作者： Lara Souza R.Travis Belote Paul Kardol jake f.weltzin Richard J.Norby Environmental Sciences Division Oak Ridge National LaboratoryBuilding 1062PO Box 2008Oak RidgeTN 37831USA Department of Ecology and Evolutionary Biology 569 Dabney HallUniversity of TennesseeKnoxvilleTN 37996USA The Wilderness Society 503 West Mendenhall St BozemanMT 59715USA USA National Phenology Network National Coordinating officeTucsonAZ 85721USA

Aims Rising concentrations of atmospheric carbon dioxide([CO_(2)])may influence forest successional development and species composition of understory plant communities by altering biomass production of plant species of functional ***,we describe how elevated[CO_(2)](eCO_(2))affects aboveground biomass within the understory community of a temperate deciduous forest at the Oak Ridge National Laboratory sweetgum(Liquidambar styraciflua)free-air carbon dioxide enrichment(fACE)facility in eastern Tennessee,*** asked if(i)CO_(2)enrichment affected total understory biomass and(ii)whether total biomass responses could be explained by changes in understory species composition or changes in relative abundance of functional groups through *** and methods The fACE experiment started in 1998 with three rings receiving ambient[CO_(2)](aCO_(2))and two rings receiving eCO_(2).from 2001 to 2003,we estimated species-specific,woody versus herbaceous and total aboveground biomass by harvesting four 130.5-m subplots within the established understory plant community in each fACE *** 2008,we estimated herbaceous biomass as previously but used allometric relationships to estimate woody biomass across two 535-m quadrats in each fACE *** findings Across years,aboveground biomass of the understory community was on average 25%greater in eCO_(2)than in aCO_(2)*** could not detect differences in plant species composition between aCO_(2)and eCO_(2)***,we did observe shifts in the relative abundance of plant functional groups,which reflect important structural changes in the understory *** 2001-03,little of the understory biomass was in woody species;herbaceous species made up 94%of the total understory biomass across[CO_(2)]*** time,woody species increased in importance,mostly in eCO_(2),and in 2008,the contribution of herbaceous species to total understory biomass was 61%in aCO_(2)and only 33%in eCO_(2)***

关键词： community composition fACE aboveground biomass woody herbaceous sweetgum Microstegium vimineum Lonicera japonica

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Responses of an old-field plant community to interacting factors of elevated[CO_(2)],warming,and soil moisture

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Journal of Plant Ecology 2009年第1期2卷 1-11页

作者： E.Cayenne Engel jake f.weltzin Richard J.Norby Aimee T.Classen Department of Ecology and Evolutionary Biology University of Tennessee569 Dabney HallKnoxvilleTN 37996-1610USA Environmental Sciences Division Oak Ridge National LaboratoryOne Bethel Valley RoadBuilding 1062Oak RidgeTN 37831-6422USA Present address:USA National Phenology Network National Coordinating Office1955 East 6th StreetTucsonAZ 85721USA

Aims The direct effects of atmospheric and climatic change factors—atmospheric[CO_(2)],air temperature and changes in precipitation—can shape plant community composition and alter ecosystem *** is essential to understand how these factors interact to make better predictions about how ecosystems may respond to *** investigated the direct and interactive effects of[CO_(2)],warming and altered soil moisture in open-top chambers(OTCs)enclosing a constructed old-field community to test how these factors shape plant *** and methods The experimental facility in Oak Ridge,TN,USA,made use of 4-m diameter OTCs and rain shelters to manipulate[CO_(2)](ambient,ambient+300 ppm),air temperature(ambient,ambient+3.5C)and soil moisture(wet,dry).The plant communities within the chambers comprised seven common old-field species,including grasses,forbs and *** tracked foliar cover for each species and calculated community richness,evenness and diversity from 2003 to *** findings This work resulted in three main findings:(1)warming had speciesspecific effects on foliar cover that varied through time and were altered by soil moisture treatments;(2)[CO_(2)]had little effect on individual species or the community;(3)diversity,evenness and richness were influenced most by soil moisture,primarily reflecting the response of one dominant *** conclude that individualistic species responses to atmospheric and climatic change can alter community composition and that plant populations and communities should be considered as part of analyses of terrestrial ecosystem response to climate ***,prediction of plant community responses may be difficult given interactions between factors and changes in response through time.

关键词： climate change foliar cover multi-factor interactions diversity richness

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Environmental implications of global hydrocarbon depletion

Environmental implications of global hydrocarbon depletion

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第三世界生态高峰会

作者： J.f.weltzin University of Tennessee USA

Modern civilization depends solely on readily available supplies of cheap energy,particularly *** evidence indicates that,as for any finite resource,global oil production will soon inevitably decline, with potentially dire consequences for societies,cultures,and the natural ecological systems that support human *** project that world oil production will peak within 20 years(though some argue that production has already peaked),and will thereafter decline at rates of 2%/annum;though reserves of oil remaining in the ground are substantial,they require increasing amounts of money and energy to extract and *** in availability must be contrasted with projected increases in demand on a global scale:world oil demand is expected to grow 50% by *** divergence between production and demand presents the world with an unprecedented risk management problem that without timely mitigation will have unprecedented economic,social,and political *** mitigation options(e.g.,improved oil recovery,non-conventional sources,substitute fuels)are possible,they must be initiated at least a decade before peak ***,mitigative options were forestalled because of their great potential for environmental impacts;in the face of overwhelming global demand for energy,environmental concerns may take a back seat to continued energy ***,it is imperative to develop a conceptual and theoretical understanding of the potential for economic,societal and environmental degradation caused by massive shifts to alternative fuel sources by an energy-dependent *** associated with peak production will be very complex,expensive,and time-consuming;as such,to fully understand the risks involved,and to develop mitigation scenarios on a timely basis,we must give the issue our immediate,serious attention. Improved scientific understanding will greatly facilitate mitigation and (as necessary)the transition to a less energy-depen

关键词： Environmental implications of global hydrocarbon depletion

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Practice parameters for the use of actigraphy in the military operational context: the Walter Reed Army Institute of Research Operational Research Kit-Actigraphy(WORK-A)

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Military Medical Research 2021年第1期8卷 103-115页

作者： Jaime K.Devine jake Choynowski Tina Burke Kajsa Carlsson Vincent f.Capaldi Ashlee B.McKeon Walter J.Sowden Operational fatigue and Performance Institutes for Behavior ResourcesBaltimoreMD 21218USA Behavioral Biology Branch Walter Reed Army Institute of Research503 Robert Grant AveSilver SpringMD 20910USA Tripler Army Medical Center HonoluluHI 96859USA

Background: The Walter Reed Army Institute of Research(WRAIR) Operational Research Kit-Actigraphy(WORK-A) is a set of unique practice parameters and actigraphy-derived measures for the analysis of operational military sleep patterns. The WORK-A draws on best practices from the literature and comprises 15 additional descriptive variables. Here, we demonstrate the WORK-A with a sample of United States Army Reserve Officers’ Training Corps(ROTC) cadets(n=286) during a month-long capstone pre-commissioning training ***: The sleep of ROTC cadets(n=286) was measured by Philips Actiwatch devices during the 31-day training exercise. The preliminary effectiveness of the WORK-A was tested by comparing differences in sleep measures collected by Actiwatches as calculated by Philips Actiware software against WORK-A-determined sleep measures and self-report sleep collected from a subset of ROTC cadets(n=140).Results: Actiware sleep summary statistics were significantly different from WORK-A measures and self-report sleep(P≤0.001). Bedtimes and waketimes as determined by WORK-A major sleep intervals showed the best agreement with self-report bedtime(22:21±1:30 vs. 22:13±0:40, P=0.21) and waketime(04:30±2:17 vs. 04:31±0:47, P=0.68). Though still significantly different, the discrepancy was smaller between the WORK-A measure of time in bed(TIB) for major sleep intervals(352±29) min and self-report nightly sleep duration [(337±57) min, P=0.006] than that between the WORK-A major TIB and Actiware TIB [(177±42) min, P≤0.001].Conclusions: Default actigraphy methods are not the most accurate methods for characterizing soldier sleep, but reliable methods for characterizing operational sleep patterns is a necessary first step in developing strategies to improve soldier readiness. The WORK-A addresses this knowledge gap by providing practice parameters and a robust variety of measures with which to profile sleep behavior in service members.

关键词： Actigraphy Sleep-wake patterns Military sleep assessment Operational environment Scoring methodology

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Could wastewater analysis be a useful tool for China?——A review

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Journal of Environmental Sciences 2015年第1期27卷 70-79页

作者： Jianfa Gao jake O'Brien foon Yin Lai Alexander L.N.van Nuijs Jun He Jochen f.Mueller Jingsha Xu Phong K.Thai faculty of Science and Engineering University of Nottingham Ningbo China National Research Centre for Environmental Toxicology The University of Queensland Toxicological Center University of Antwerp

Analysing wastewater samples is an innovative approach that overcomes many limitations of traditional surveys to identify and measure a range of chemicals that were consumed by or exposed to people living in a sewer catchment area. first conceptualised in 2001, much progress has been made to make wastewater analysis（WWA） a reliable and robust tool for measuring chemical consumption and/or exposure. At the moment, the most popular application of WWA, sometimes referred as sewage epidemiology, is to monitor the consumption of illicit drugs in communities around the globe, including China. The approach has been largely adopted by law enforcement agencies as a device to monitor the temporal and geographical patterns of drug consumption. In the future, the methodology can be extended to other chemicals including biomarkers of population health（e.g. environmental or oxidative stress biomarkers, lifestyle indicators or medications that are taken by different demographic groups） and pollutants that people are exposed to（e.g. polycyclic aromatic hydrocarbons,perfluorinated chemicals, and toxic pesticides）. The extension of WWA to a huge range of chemicals may give rise to a field called sewage chemical-information mining（SCIM） with unexplored potentials. China has many densely populated cities with thousands of sewage treatment plants which are favourable for applying WWA/SCIM in order to help relevant authorities gather information about illicit drug consumption and population health status. However, there are some prerequisites and uncertainties of the methodology that should be addressed for SCIM to reach its full potential in China.

关键词： Drug consumption Wastewater analysis Biomarkers Population health

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Evaluation of maize inbred lines and topcross progeny for resistance to pre-harvest aflatoxin contamination

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The Crop Journal 2019年第1期7卷 118-125页

作者： jake C.fountain Hamed K.Abbas Brian T.Scully Hong Li Robert D.Lee Robert C.Kemerait Baozhu Guo USDA-ARS Crop Protection and Management Research Unit Department of Plant Pathology University of Georgia USDA-ARS Biological Control of Pests Research Unit USDA-ARS National Horticultural Research Laboratory Shanxi Academy of Agricultural Sciences Millet Research Institute Department of Crop and Soil Sciences University of Georgia

Pre-harvest aflatoxin contamination occurs in maize following kernel colonization by Aspergillus flavus. Aflatoxin contamination resistance is a highly desired trait in maize breeding *** identification of novel sources of resistance to pre-harvest aflatoxin contamination is a major focus in germplasm screening efforts. Here, we performed a field evaluation of 64 inbred lines over two years for pre-harvest aflatoxin contamination. Topcrosses were also performed with two testers, B73 and Mo17, to generate 128 f1 hybrids which were also evaluated over two years. Hybrid performance was used to calculate both general combining ability(GCA) of the inbreds, and observed heterosis for aflatoxin resistance. Over both years of the study, aflatoxin concentrations ranged from 80 ± 47 to 17,617 ± 8816 μg kg^(-1) for inbreds, and from 58 ± 39 to 2771 ± 780 μg kg^(-1) for hybrids with significant variation between years and lines. The inbred lines CML52, CML69, CML247, GT-603, GEMS-0005, Hi63, Hp301, and M37 W showed f aflatoxin accumulation in both years of the study and less than the resistant check, Mp313 E, in at least one season. Among these, CML52, GT-603, and Hi63 also showed significant GCA with the testers in hybrid progeny. CML52, GT-603, and M37 W also showed heterotic effects of-13.64%,-12.47%, and-24.50%, respectively, with B73 resulting in reduced aflatoxin contamination. GT-603 also showed a similar heterotic effect for aflatoxin contamination,-13.11%, with Mo17 indicating that this line may serve as a versatile source of aflatoxin contamination resistance in breeding programs.

关键词： Aspergillus flavus Pre-harvest Aflatoxin Maize Topcross

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An external quantum efficiency of>20%from solutionprocessed poly(dendrimer)organic light-emitting diodes

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npj flexible Electronics 2018年第1期2卷 213-218页

作者： fatemeh Maasoumi Ross D.Jansen-van Vuuren Paul E.Shaw Emma V.Puttock Ravi Chandra Raju Nagiri jake A.McEwan Mark Bown Jenny L.O’Connell Christopher J.Dunn Paul L.Burn Ebinazar B.Namdas Centre for Organic Photonics&Electronics(COPE) School of Chemistry&Molecular Biosciences and School of Mathematics&PhysicsUniversity of QueenslandSt.LuciaQLD 4072Australia CSIRO Manufacturing Research WayClaytonVIC 3168Australia

Controlling the orientation of the emissive dipole has led to a renaissance of organic light-emitting diode(OLED)research,with external quantum efficiencies(EQEs)of>30%being reported for phosphorescent *** highly efficient OLEDs are generally manufactured using evaporative methods and are comprised of small-molecule heteroleptic phosphorescent iridium(III)complexes blended with a host and additional layers to balance charge injection and *** area OLEDs for lighting and display applications would benefit from low-cost solution processing,provided that high EQEs could be ***,we show that poly(dendrimer)s consisting of a non-conjugated polymer backbone with iridium(III)complexes forming the cores of firstgeneration dendrimer side chains can be co-deposited with a host by solution processing to give highly efficient *** bilayer devices comprising the emissive layer and an electron transport layer gave an EQE of>20%at luminances of up to≈300 cd/m^(2),showing that polymer engineering can enable alignment of the emissive dipole of solution-processed phosphorescent materials.

关键词： quantum dipole light

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短线交易五大绝技

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作者： (美)杰克·伯恩斯坦(jake Bernstein)[]

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