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  • 1
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    Manta birostris, predator of the deep? Insight into the diet of the giant manta ray through stable isotope analysis (2016)
    Royal Society
    Details
    Publication Date: 2016-12-01
    Description: The characterization of diet for the giant manta ray Manta birostris has been problematic given their large-scale movement patterns and the difficulty in obtaining stomach contents from this species. The large majority of existing information is based on observational data limited to feeding events at the sea surface during daylight. Recently discovered aggregation sites for the giant manta ray off mainland Ecuador are some of the most accessible to date and provide a unique opportunity for researchers to gather much needed information on this elusive species. To assess how important surface zooplankton is to giant manta ray diet, we conducted stable isotope analysis ( 15 N and 13 C) on M. birostris muscle and surface zooplankton. Trophic position estimates placed M. birostris overall at a secondary consumer level of approximately 3.4 but there was large variation in 15 N and 13 C values among individuals. Manta birostris muscle tissue 13 C values were also not consistent with this species feeding predominantly on surface zooplankton and suggest that the majority of dietary intake is of mesopelagic origin. Given the conservative life history and fisheries pressure on large planktivores, knowledge of their trophic role and foraging strategies is essential to better understand their ecology and develop effective conservation measures.
    Keywords: biochemistry, ecology
    Electronic ISSN: 2054-5703
    Topics: Natural Sciences in General
    Published by Royal Society
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  • 2
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    Seasonal variation of photosynthetic model parameters and leaf area index from global Fluxnet eddy covariance data (2011)
    Wiley
    Details
    Publication Date: 2011-12-15
    Description: Global vegetation models require the photosynthetic parameters, maximum carboxylation capacity (Vcm), and quantum yield (α) to parameterize their plant functional types (PFTs). The purpose of this work is to determine how much the scaling of the parameters from leaf to ecosystem level through a seasonally varying leaf area index (LAI) explains the parameter variation within and between PFTs. Using Fluxnet data, we simulate a seasonally variable LAIF for a large range of sites, comparable to the LAIM derived from MODIS. There are discrepancies when LAIF reach zero levels and LAIM still provides a small positive value. We find that temperature is the most common constraint for LAIF in 55% of the simulations, while global radiation and vapor pressure deficit are the key constraints for 18% and 27% of the simulations, respectively, while large differences in this forcing still exist when looking at specific PFTs. Despite these differences, the annual photosynthesis simulations are comparable when using LAIF or LAIM (r2 = 0.89). We investigated further the seasonal variation of ecosystem-scale parameters derived with LAIF. Vcm has the largest seasonal variation. This holds for all vegetation types and climates. The parameter α is less variable. By including ecosystem-scale parameter seasonality we can explain a considerable part of the ecosystem-scale parameter variation between PFTs. The remaining unexplained leaf-scale PFT variation still needs further work, including elucidating the precise role of leaf and soil level nitrogen.
    Print ISSN: 0148-0227
    Topics: Biology , Geosciences
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 3
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    Net carbon dioxide losses of northern ecosystems in response to autumn warming (2008)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2008-01-04
    Description: The carbon balance of terrestrial ecosystems is particularly sensitive to climatic changes in autumn and spring, with spring and autumn temperatures over northern latitudes having risen by about 1.1 degrees C and 0.8 degrees C, respectively, over the past two decades. A simultaneous greening trend has also been observed, characterized by a longer growing season and greater photosynthetic activity. These observations have led to speculation that spring and autumn warming could enhance carbon sequestration and extend the period of net carbon uptake in the future. Here we analyse interannual variations in atmospheric carbon dioxide concentration data and ecosystem carbon dioxide fluxes. We find that atmospheric records from the past 20 years show a trend towards an earlier autumn-to-winter carbon dioxide build-up, suggesting a shorter net carbon uptake period. This trend cannot be explained by changes in atmospheric transport alone and, together with the ecosystem flux data, suggest increasing carbon losses in autumn. We use a process-based terrestrial biosphere model and satellite vegetation greenness index observations to investigate further the observed seasonal response of northern ecosystems to autumnal warming. We find that both photosynthesis and respiration increase during autumn warming, but the increase in respiration is greater. In contrast, warming increases photosynthesis more than respiration in spring. Our simulations and observations indicate that northern terrestrial ecosystems may currently lose carbon dioxide in response to autumn warming, with a sensitivity of about 0.2 PgC degrees C(-1), offsetting 90% of the increased carbon dioxide uptake during spring. If future autumn warming occurs at a faster rate than in spring, the ability of northern ecosystems to sequester carbon may be diminished earlier than previously suggested.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Piao, Shilong -- Ciais, Philippe -- Friedlingstein, Pierre -- Peylin, Philippe -- Reichstein, Markus -- Luyssaert, Sebastiaan -- Margolis, Hank -- Fang, Jingyun -- Barr, Alan -- Chen, Anping -- Grelle, Achim -- Hollinger, David Y -- Laurila, Tuomas -- Lindroth, Anders -- Richardson, Andrew D -- Vesala, Timo -- England -- Nature. 2008 Jan 3;451(7174):49-52. doi: 10.1038/nature06444.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉LSCE, UMR CEA-CNRS, Batiment 709, CE, L'Orme des Merisiers, F-91191 Gif-sur-Yvette, France. slpiao@lsce.ipsl.fr〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18172494" target="_blank"〉PubMed〈/a〉
    Keywords: Atmosphere/chemistry ; Biomass ; Carbon Dioxide/analysis/*metabolism ; Cell Respiration ; *Ecosystem ; Fossil Fuels ; Geography ; Greenhouse Effect ; History, 20th Century ; History, 21st Century ; Oceans and Seas ; Photosynthesis ; Plant Transpiration ; Plants/metabolism ; Rain ; *Seasons ; Soil/analysis ; *Temperature ; Water/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 4
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    Recent decline in the global land evapotranspiration trend due to limited moisture supply (2010)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2010-10-12
    Description: More than half of the solar energy absorbed by land surfaces is currently used to evaporate water. Climate change is expected to intensify the hydrological cycle and to alter evapotranspiration, with implications for ecosystem services and feedback to regional and global climate. Evapotranspiration changes may already be under way, but direct observational constraints are lacking at the global scale. Until such evidence is available, changes in the water cycle on land-a key diagnostic criterion of the effects of climate change and variability-remain uncertain. Here we provide a data-driven estimate of global land evapotranspiration from 1982 to 2008, compiled using a global monitoring network, meteorological and remote-sensing observations, and a machine-learning algorithm. In addition, we have assessed evapotranspiration variations over the same time period using an ensemble of process-based land-surface models. Our results suggest that global annual evapotranspiration increased on average by 7.1 +/- 1.0 millimetres per year per decade from 1982 to 1997. After that, coincident with the last major El Nino event in 1998, the global evapotranspiration increase seems to have ceased until 2008. This change was driven primarily by moisture limitation in the Southern Hemisphere, particularly Africa and Australia. In these regions, microwave satellite observations indicate that soil moisture decreased from 1998 to 2008. Hence, increasing soil-moisture limitations on evapotranspiration largely explain the recent decline of the global land-evapotranspiration trend. Whether the changing behaviour of evapotranspiration is representative of natural climate variability or reflects a more permanent reorganization of the land water cycle is a key question for earth system science.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jung, Martin -- Reichstein, Markus -- Ciais, Philippe -- Seneviratne, Sonia I -- Sheffield, Justin -- Goulden, Michael L -- Bonan, Gordon -- Cescatti, Alessandro -- Chen, Jiquan -- de Jeu, Richard -- Dolman, A Johannes -- Eugster, Werner -- Gerten, Dieter -- Gianelle, Damiano -- Gobron, Nadine -- Heinke, Jens -- Kimball, John -- Law, Beverly E -- Montagnani, Leonardo -- Mu, Qiaozhen -- Mueller, Brigitte -- Oleson, Keith -- Papale, Dario -- Richardson, Andrew D -- Roupsard, Olivier -- Running, Steve -- Tomelleri, Enrico -- Viovy, Nicolas -- Weber, Ulrich -- Williams, Christopher -- Wood, Eric -- Zaehle, Sonke -- Zhang, Ke -- England -- Nature. 2010 Oct 21;467(7318):951-4. doi: 10.1038/nature09396.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Max Planck Institute for Biogeochemistry, 07745 Jena, Germany. mjung@bgc-jena.mpg.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20935626" target="_blank"〉PubMed〈/a〉
    Keywords: Artificial Intelligence ; Atmosphere/*chemistry ; Fresh Water/*analysis ; *Global Warming/statistics & numerical data ; History, 20th Century ; History, 21st Century ; Humidity ; Plant Transpiration/*physiology ; Reproducibility of Results ; Seasons ; Soil/analysis ; Uncertainty ; Volatilization ; *Water Cycle
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 5
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    Observed increase in local cooling effect of deforestation at higher latitudes (2011)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2011-11-19
    Description: Deforestation in mid- to high latitudes is hypothesized to have the potential to cool the Earth's surface by altering biophysical processes. In climate models of continental-scale land clearing, the cooling is triggered by increases in surface albedo and is reinforced by a land albedo-sea ice feedback. This feedback is crucial in the model predictions; without it other biophysical processes may overwhelm the albedo effect to generate warming instead. Ongoing land-use activities, such as land management for climate mitigation, are occurring at local scales (hectares) presumably too small to generate the feedback, and it is not known whether the intrinsic biophysical mechanism on its own can change the surface temperature in a consistent manner. Nor has the effect of deforestation on climate been demonstrated over large areas from direct observations. Here we show that surface air temperature is lower in open land than in nearby forested land. The effect is 0.85 +/- 0.44 K (mean +/- one standard deviation) northwards of 45 degrees N and 0.21 +/- 0.53 K southwards. Below 35 degrees N there is weak evidence that deforestation leads to warming. Results are based on comparisons of temperature at forested eddy covariance towers in the USA and Canada and, as a proxy for small areas of cleared land, nearby surface weather stations. Night-time temperature changes unrelated to changes in surface albedo are an important contributor to the overall cooling effect. The observed latitudinal dependence is consistent with theoretical expectation of changes in energy loss from convection and radiation across latitudes in both the daytime and night-time phase of the diurnal cycle, the latter of which remains uncertain in climate models.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lee, Xuhui -- Goulden, Michael L -- Hollinger, David Y -- Barr, Alan -- Black, T Andrew -- Bohrer, Gil -- Bracho, Rosvel -- Drake, Bert -- Goldstein, Allen -- Gu, Lianhong -- Katul, Gabriel -- Kolb, Thomas -- Law, Beverly E -- Margolis, Hank -- Meyers, Tilden -- Monson, Russell -- Munger, William -- Oren, Ram -- Paw U, Kyaw Tha -- Richardson, Andrew D -- Schmid, Hans Peter -- Staebler, Ralf -- Wofsy, Steven -- Zhao, Lei -- England -- Nature. 2011 Nov 16;479(7373):384-7. doi: 10.1038/nature10588.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511, USA. xuhui.lee@yale.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22094699" target="_blank"〉PubMed〈/a〉
    Keywords: Air/analysis ; *Altitude ; Atmosphere/analysis ; Biophysical Processes ; Canada ; Climate ; Conservation of Natural Resources ; Forestry ; Seasons ; *Temperature ; Trees/*growth & development ; United States
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 6
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    Increase in forest water-use efficiency as atmospheric carbon dioxide concentrations rise (2013)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2013-07-12
    Description: Terrestrial plants remove CO2 from the atmosphere through photosynthesis, a process that is accompanied by the loss of water vapour from leaves. The ratio of water loss to carbon gain, or water-use efficiency, is a key characteristic of ecosystem function that is central to the global cycles of water, energy and carbon. Here we analyse direct, long-term measurements of whole-ecosystem carbon and water exchange. We find a substantial increase in water-use efficiency in temperate and boreal forests of the Northern Hemisphere over the past two decades. We systematically assess various competing hypotheses to explain this trend, and find that the observed increase is most consistent with a strong CO2 fertilization effect. The results suggest a partial closure of stomata-small pores on the leaf surface that regulate gas exchange-to maintain a near-constant concentration of CO2 inside the leaf even under continually increasing atmospheric CO2 levels. The observed increase in forest water-use efficiency is larger than that predicted by existing theory and 13 terrestrial biosphere models. The increase is associated with trends of increasing ecosystem-level photosynthesis and net carbon uptake, and decreasing evapotranspiration. Our findings suggest a shift in the carbon- and water-based economics of terrestrial vegetation, which may require a reassessment of the role of stomatal control in regulating interactions between forests and climate change, and a re-evaluation of coupled vegetation-climate models.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Keenan, Trevor F -- Hollinger, David Y -- Bohrer, Gil -- Dragoni, Danilo -- Munger, J William -- Schmid, Hans Peter -- Richardson, Andrew D -- England -- Nature. 2013 Jul 18;499(7458):324-7. doi: 10.1038/nature12291. Epub 2013 Jul 10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA. tkeenan@oeb.harvard.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23842499" target="_blank"〉PubMed〈/a〉
    Keywords: Atmosphere/chemistry ; Carbon Dioxide/*analysis ; *Ecosystem ; Plant Leaves/chemistry ; Trees/*chemistry ; Water/*analysis
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 7
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    Keenan et al. reply (2014)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2014-03-14
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Keenan, Trevor F -- Hollinger, David Y -- Bohrer, Gil -- Dragoni, Danilo -- Munger, J William -- Schmid, Hans Peter -- Richardson, Andrew D -- England -- Nature. 2014 Mar 13;507(7491):E2-3. doi: 10.1038/nature13114.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Sciences, Macquarie University, North Ryde, New South Wales 2109, Australia. ; USDA Forest Service, Northern Research Station, Durham, New Hamphire 03824, USA. ; Department of Civil, Environmental and Geodetic Engineering, The Ohio State University, Columbus, Ohio 43210, USA. ; Department of Geography, Indiana University, Bloomington, Indiana 47405, USA. ; School of Engineering and Applied Sciences and Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, USA. ; Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, IMK-IFU, Garmisch-Partenkirchen 82467, Germany. ; Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24622207" target="_blank"〉PubMed〈/a〉
    Keywords: Carbon Dioxide/*analysis ; *Ecosystem ; Trees/*chemistry ; Water/*analysis
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 8
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    Global convergence in the temperature sensitivity of respiration at ecosystem level (2010)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2010-07-07
    Description: The respiratory release of carbon dioxide (CO(2)) from the land surface is a major flux in the global carbon cycle, antipodal to photosynthetic CO(2) uptake. Understanding the sensitivity of respiratory processes to temperature is central for quantifying the climate-carbon cycle feedback. We approximated the sensitivity of terrestrial ecosystem respiration to air temperature (Q(10)) across 60 FLUXNET sites with the use of a methodology that circumvents confounding effects. Contrary to previous findings, our results suggest that Q(10) is independent of mean annual temperature, does not differ among biomes, and is confined to values around 1.4 +/- 0.1. The strong relation between photosynthesis and respiration, by contrast, is highly variable among sites. The results may partly explain a less pronounced climate-carbon cycle feedback than suggested by current carbon cycle climate models.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mahecha, Miguel D -- Reichstein, Markus -- Carvalhais, Nuno -- Lasslop, Gitta -- Lange, Holger -- Seneviratne, Sonia I -- Vargas, Rodrigo -- Ammann, Christof -- Arain, M Altaf -- Cescatti, Alessandro -- Janssens, Ivan A -- Migliavacca, Mirco -- Montagnani, Leonardo -- Richardson, Andrew D -- New York, N.Y. -- Science. 2010 Aug 13;329(5993):838-40. doi: 10.1126/science.1189587. Epub 2010 Jul 5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Max Planck Institute for Biogeochemistry, 07745 Jena, Germany. mmahecha@bgc-jena.mpg.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20603495" target="_blank"〉PubMed〈/a〉
    Keywords: Carbon/metabolism ; Carbon Dioxide/*metabolism ; Cell Respiration ; *Climate ; Ecological and Environmental Processes ; *Ecosystem ; Models, Biological ; Models, Statistical ; Photosynthesis ; Plants/*metabolism ; Soil/analysis ; Soil Microbiology ; *Temperature
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 9
    Electronic Resource
    Electronic Resource
    Coherent Raman observations of factor group splittings and lattice vibrations in nanocrystals formed in supersonic expansions (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 10100-10101 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Coherent anti-Stokes Raman spectra are reported for solid, nanometer-sized C2H2 and CO2 aggregates formed in free jet expansions. From comparisons with spectra of equilibrium samples, the clusters are seen to be face centered cubic with a crystalline character indicated by the appearance of vibrational factor group splittings and, for CO2, by the observation of two external lattice librations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.464400
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  • 10
    Electronic Resource
    Electronic Resource
    Spatial and temporal variability in forest–atmosphere CO2 exchange (2004)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 10 (2004), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Seven years of carbon dioxide flux measurements indicate that a ∼90-year-old spruce dominated forest in Maine, USA, has been sequestering 174±46 g C m−2 yr−1 (mean±1 standard deviation, nocturnal friction velocity (u*) threshold 〉0.25 m s−1). An analysis of monthly flux anomalies showed that above-average spring and fall temperatures were significantly correlated with greater monthly C uptake while above-average summer temperatures were correlated with decreased net C uptake. Summer months with significantly drier or wetter soils than normal were also characterized by lower rates of C uptake. Years with above-average C storage were thus typically characterized by warmer than average spring and fall temperatures and adequate summer soil moisture.Environmental and forest–atmosphere flux data recorded from a second tower surrounded by similar forest, but sufficiently distant that flux source regions (‘footprints’), did not overlap significantly showed almost identical temperature and solar radiation conditions, but some differences in energy partitioning could be seen. Half-hourly as well as integrated (annual) C exchange values recorded at the separate towers were very similar, with average annual net C uptake differing between the two towers by 〈6%. Interannual variability in net C exchange was found to be much greater than between tower variability. Simultaneous measurements from two towers were used to estimate flux data uncertainty from a single tower. Carbon-flux model parameters derived independently from each flux tower data set were not significantly different, demonstrating that flux towers can provide a robust method for establishing C exchange model parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2486.2004.00847.x
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