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Ding J, McDowell N, Fang Y, Ward N, Kirwan ML, Regier P, Megonigal P, Zhang P, Zhang H, Wang W, Li W, Pennington SC, Wilson SJ, Stearns A, Bailey V. Modeling the mechanisms of conifer mortality under seawater exposure. New Phytol 2023. [PMID: 37376720 DOI: 10.1111/nph.19076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 05/26/2023] [Indexed: 06/29/2023]
Abstract
Relative sea level rise (SLR) increasingly impacts coastal ecosystems through the formation of ghost forests. To predict the future of coastal ecosystems under SLR and changing climate, it is important to understand the physiological mechanisms underlying coastal tree mortality and to integrate this knowledge into dynamic vegetation models. We incorporate the physiological effect of salinity and hypoxia in a dynamic vegetation model in the Earth system land model, and used the model to investigate the mechanisms of mortality of conifer forests on the west and east coast sites of USA, where trees experience different form of sea water exposure. Simulations suggest similar physiological mechanisms can result in different mortality patterns. At the east coast site that experienced severe increases in seawater exposure, trees loose photosynthetic capacity and roots rapidly, and both storage carbon and hydraulic conductance decrease significantly within a year. Over time, further consumption of storage carbon that leads to carbon starvation dominates mortality. At the west coast site that gradually exposed to seawater through SLR, hydraulic failure dominates mortality because root loss impacts on conductance are greater than the degree of storage carbon depletion. Measurements and modeling focused on understanding the physiological mechanisms of mortality is critical to reducing predictive uncertainty.
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Affiliation(s)
- Junyan Ding
- Biological Sciences Division, Pacific Northwest National Lab, PO Box 999, Richland, WA, 99352, USA
| | - Nate McDowell
- Biological Sciences Division, Pacific Northwest National Lab, PO Box 999, Richland, WA, 99352, USA
- School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA, 99164-4236, USA
| | - Yilin Fang
- Earth Systems Science Division, Pacific Northwest National Lab, Richland, WA, 99352, USA
| | - Nicholas Ward
- Marine and Coastal Research Laboratory, Pacific Northwest National Laboratory, Sequim, WA, 98382, USA
| | - Matthew L Kirwan
- Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, VA, 23062, USA
| | - Peter Regier
- Marine and Coastal Research Laboratory, Pacific Northwest National Laboratory, Sequim, WA, 98382, USA
| | - Patrick Megonigal
- Smithsonian Environmental Research Center, Edgewater, MD, 21037, USA
| | - Peipei Zhang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, China
| | - Hongxia Zhang
- Shapotou Desert Research and Experiment Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China
| | - Wenzhi Wang
- The Key Laboratory of Mountain Environment Evolution and Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, 610041, China
| | - Weibin Li
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China
| | - Stephanie C Pennington
- Joint Global Change Research Institute, Pacific Northwest National Laboratory, College Park, MD, 20740, USA
| | | | - Alice Stearns
- Smithsonian Environmental Research Center, Edgewater, MD, 21037, USA
| | - Vanessa Bailey
- Biological Sciences Division, Pacific Northwest National Lab, PO Box 999, Richland, WA, 99352, USA
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2
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Jardine KJ, McDowell N. Fermentation-mediated growth, signaling, and defense in plants. New Phytol 2023. [PMID: 37282715 DOI: 10.1111/nph.19015] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 03/18/2023] [Indexed: 06/08/2023]
Abstract
While traditionally considered important mainly in hypoxic roots during flooding, upregulation of fermentation pathways in plants has recently been described as an evolutionarily conserved drought survival strategy, with acetate signaling mediating reprograming of transcription and cellular carbon and energy metabolism from roots to leaves. The amount of acetate produced directly correlates with survival through potential mechanisms including defense gene activation, biosynthesis of primary and secondary metabolites, and aerobic respiration. Here, we review root ethanolic fermentation responses to hypoxia during saturated soil conditions and summarize studies highlighting acetate fermentation under aerobic conditions coupled with respiration during growth and drought responses. Recent work is discussed demonstrating long-distance transport of acetate via the transpiration stream as a respiratory substrate. While maintenance and growth respiration are often modeled separately in terrestrial models, here we propose the concept of 'Defense Respiration' fueled by acetate fermentation in which upregulation of acetate fermentation contributes acetate substrate for alternative energy production via aerobic respiration, biosynthesis of primary and secondary metabolites, and the acetylation of proteins involved in defense gene regulation. Finally, we highlight new frontiers in leaf-atmosphere emission measurements as a potential way to study acetate fermentation responses of individual leaves, branches, ecosystems, and regions.
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Affiliation(s)
- Kolby J Jardine
- Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Ciências de Florestas Tropicais, National Institute for Amazon Research, Manaus, 69067, Amazonas, Brazil
| | - Nate McDowell
- Atmospheric Sciences and Global Change Division, Pacific Northwest National Lab, Richland, WA, 99354, USA
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
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3
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Hopple AM, Doro KO, Bailey VL, Bond-Lamberty B, McDowell N, Morris KA, Myers-Pigg A, Pennington SC, Regier P, Rich R, Sengupta A, Smith R, Stegen J, Ward ND, Woodard SC, Megonigal JP. Attaining freshwater and estuarine-water soil saturation in an ecosystem-scale coastal flooding experiment. Environ Monit Assess 2023; 195:425. [PMID: 36826723 PMCID: PMC9958149 DOI: 10.1007/s10661-022-10807-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 12/02/2022] [Indexed: 06/18/2023]
Abstract
Coastal upland forests are facing widespread mortality as sea-level rise accelerates and precipitation and storm regimes change. The loss of coastal forests has significant implications for the coastal carbon cycle; yet, predicting mortality likelihood is difficult due to our limited understanding of disturbance impacts on coastal forests. The manipulative, ecosystem-scale Terrestrial Ecosystem Manipulation to Probe the Effects of Storm Treatments (TEMPEST) experiment addresses the potential for freshwater and estuarine-water disturbance events to alter tree function, species composition, and ecosystem processes in a deciduous coastal forest in MD, USA. The experiment uses a large-unit (2000 m2), un-replicated experimental design, with three 50 m × 40 m plots serving as control, freshwater, and estuarine-water treatments. Transient saturation (5 h) of the entire soil rooting zone (0-30 cm) across a 2000 m2 coastal forest was attained by delivering 300 m3 of water through a spatially distributed irrigation network at a rate just above the soil infiltration rate. Our water delivery approach also elevated the water table (typically ~ 2 m belowground) and achieved extensive, low-level inundation (~ 8 cm standing water). A TEMPEST simulation approximated a 15-cm rainfall event and based on historic records, was of comparable intensity to a 10-year storm for the area. This characterization was supported by showing that Hurricane Ida's (~ 5 cm rainfall) hydrologic impacts were shorter (40% lower duration) and less expansive (80% less coverage) than those generated through experimental manipulation. Future work will apply TEMPEST treatments to evaluate coastal forest resilience to changing hydrologic disturbance regimes and identify conditions that initiate ecosystem state transitions.
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Affiliation(s)
- A. M. Hopple
- Pacific Northwest National Laboratory, Richland, WA 99352 USA
- Smithsonian Environmental Research Center, Edgewater, MD 21037 USA
| | - K. O. Doro
- University of Toledo, Toledo, OH 43606 USA
| | - V. L. Bailey
- Pacific Northwest National Laboratory, Richland, WA 99352 USA
| | - B. Bond-Lamberty
- Joint Global Change Research Institute, Pacific Northwest National Laboratory, College Park, MD 20740 USA
| | - N. McDowell
- Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, WA 99352 Richland, USA
- School of Biological Sciences, Washington State University, Pullman, WA 99164 USA
| | - K. A. Morris
- Joint Global Change Research Institute, Pacific Northwest National Laboratory, College Park, MD 20740 USA
| | - A. Myers-Pigg
- University of Toledo, Toledo, OH 43606 USA
- Marine and Coastal Research Laboratory, Pacific Northwest National Laboratory, Sequim, WA 98382 USA
| | - S. C. Pennington
- Joint Global Change Research Institute, Pacific Northwest National Laboratory, College Park, MD 20740 USA
| | - P. Regier
- Marine and Coastal Research Laboratory, Pacific Northwest National Laboratory, Sequim, WA 98382 USA
| | - R. Rich
- Smithsonian Environmental Research Center, Edgewater, MD 21037 USA
| | - A. Sengupta
- California Lutheran University, Thousand Oaks, CA 91360 USA
| | - R. Smith
- Global Aquatic Research LLC, Sodus, NY 14551 USA
| | - J. Stegen
- Pacific Northwest National Laboratory, Richland, WA 99352 USA
| | - N. D. Ward
- Marine and Coastal Research Laboratory, Pacific Northwest National Laboratory, Sequim, WA 98382 USA
- University of Washington, Seattle, WA 98195 USA
| | | | - J. P. Megonigal
- Smithsonian Environmental Research Center, Edgewater, MD 21037 USA
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4
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Konings AG, Saatchi SS, Frankenberg C, Keller M, Leshyk V, Anderegg WRL, Humphrey V, Matheny AM, Trugman A, Sack L, Agee E, Barnes ML, Binks O, Cawse‐Nicholson K, Christoffersen BO, Entekhabi D, Gentine P, Holtzman NM, Katul GG, Liu Y, Longo M, Martinez‐Vilalta J, McDowell N, Meir P, Mencuccini M, Mrad A, Novick KA, Oliveira RS, Siqueira P, Steele‐Dunne SC, Thompson DR, Wang Y, Wehr R, Wood JD, Xu X, Zuidema PA. Detecting forest response to droughts with global observations of vegetation water content. Glob Chang Biol 2021; 27:6005-6024. [PMID: 34478589 PMCID: PMC9293345 DOI: 10.1111/gcb.15872] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 08/23/2021] [Indexed: 05/11/2023]
Abstract
Droughts in a warming climate have become more common and more extreme, making understanding forest responses to water stress increasingly pressing. Analysis of water stress in trees has long focused on water potential in xylem and leaves, which influences stomatal closure and water flow through the soil-plant-atmosphere continuum. At the same time, changes of vegetation water content (VWC) are linked to a range of tree responses, including fluxes of water and carbon, mortality, flammability, and more. Unlike water potential, which requires demanding in situ measurements, VWC can be retrieved from remote sensing measurements, particularly at microwave frequencies using radar and radiometry. Here, we highlight key frontiers through which VWC has the potential to significantly increase our understanding of forest responses to water stress. To validate remote sensing observations of VWC at landscape scale and to better relate them to data assimilation model parameters, we introduce an ecosystem-scale analog of the pressure-volume curve, the non-linear relationship between average leaf or branch water potential and water content commonly used in plant hydraulics. The sources of variability in these ecosystem-scale pressure-volume curves and their relationship to forest response to water stress are discussed. We further show to what extent diel, seasonal, and decadal dynamics of VWC reflect variations in different processes relating the tree response to water stress. VWC can also be used for inferring belowground conditions-which are difficult to impossible to observe directly. Lastly, we discuss how a dedicated geostationary spaceborne observational system for VWC, when combined with existing datasets, can capture diel and seasonal water dynamics to advance the science and applications of global forest vulnerability to future droughts.
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Affiliation(s)
| | - Sassan S. Saatchi
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | | | - Michael Keller
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
- United States Forest ServiceWashingtonDCUSA
| | | | | | | | | | - Anna Trugman
- University of California ‐ Santa BarbaraSanta BarbaraCAUSA
| | - Lawren Sack
- University of California ‐ Los AngelesLos AngelesCAUSA
| | | | | | - Oliver Binks
- The Australian National UniversityCanberraACTAustralia
| | | | | | | | | | | | | | | | - Marcos Longo
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - Jordi Martinez‐Vilalta
- Centre de Recerca Ecològica i Aplicacions Forestals (CREAF)BarcelonaSpain
- Universitat Autònoma de BarcelonaBarcelonaSpain
| | - Nate McDowell
- Pacific Northwest National LaboratoryRichlandWAUSA
- Washington State UniversityPullmanWAUSA
| | - Patrick Meir
- The Australian National UniversityCanberraACTAustralia
- University of EdinburghEdinburghUK
| | - Maurizio Mencuccini
- Centre de Recerca Ecològica i Aplicacions Forestals (CREAF)BarcelonaSpain
- Institució Catalana de Recerca i Estudis Avançats (ICREA)BarcelonaSpain
| | - Assaad Mrad
- University of California ‐ IrvineIrvineCAUSA
| | | | | | | | | | - David R. Thompson
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - Yujie Wang
- California Institute of TechnologyPasadenaCAUSA
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5
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Pivovaroff AL, Wolfe BT, McDowell N, Christoffersen B, Davies S, Dickman LT, Grossiord C, Leff RT, Rogers A, Serbin SP, Wright SJ, Wu J, Xu C, Chambers JQ. Hydraulic architecture explains species moisture dependency but not mortality rates across a tropical rainfall gradient. Biotropica 2021. [DOI: 10.1111/btp.12964] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Alexandria L. Pivovaroff
- Atmospheric Science and Global Change Division Pacific Northwest National Laboratory Richland WA USA
| | - Brett T. Wolfe
- Smithsonian Tropical Research Institute Balboa Republic of Panama
- School of Renewable Natural Resources Louisiana State University Baton Rouge LA USA
| | - Nate McDowell
- Atmospheric Science and Global Change Division Pacific Northwest National Laboratory Richland WA USA
| | | | - Stuart Davies
- Smithsonian Tropical Research Institute Balboa Republic of Panama
| | - L. Turin Dickman
- Earth and Environmental Sciences Division Los Alamos National Laboratory Los Alamos NM USA
| | - Charlotte Grossiord
- Functional Plant Ecology Community Ecology Unit Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) Lausanne Switzerland
- School of Architecture Civil and Environmental Engineering ENAC Plant Ecology Research Laboratory – PERL EPFL Lausanne Switzerland
| | - Riley T. Leff
- Atmospheric Science and Global Change Division Pacific Northwest National Laboratory Richland WA USA
| | - Alistair Rogers
- Brookhaven National Laboratory, Environmental and Climate Sciences Upton NY USA
| | - Shawn P. Serbin
- Brookhaven National Laboratory, Environmental and Climate Sciences Upton NY USA
| | - S. Joseph Wright
- Smithsonian Tropical Research Institute Balboa Republic of Panama
| | - Jin Wu
- Brookhaven National Laboratory, Environmental and Climate Sciences Upton NY USA
- School of Biological Sciences The University of Hong Kong Hong Kong Hong Kong
| | - Chonggang Xu
- Earth and Environmental Sciences Division Los Alamos National Laboratory Los Alamos NM USA
| | - Jeffrey Q. Chambers
- Lawrence Berkeley National Laboratory Earth and Environmental Science Area Berkeley CA USA
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6
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Rodrigues TB, Baker CR, Walker AP, McDowell N, Rogers A, Higuchi N, Chambers JQ, Jardine KJ. Stimulation of isoprene emissions and electron transport rates as key mechanisms of thermal tolerance in the tropical species Vismia guianensis. Glob Chang Biol 2020; 26:5928-5941. [PMID: 32525272 DOI: 10.1111/gcb.15213] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 04/14/2020] [Accepted: 05/28/2020] [Indexed: 06/11/2023]
Abstract
Tropical forests absorb large amounts of atmospheric CO2 through photosynthesis, but high surface temperatures suppress this absorption while promoting isoprene emissions. While mechanistic isoprene emission models predict a tight coupling to photosynthetic electron transport (ETR) as a function of temperature, direct field observations of this phenomenon are lacking in the tropics and are necessary to assess the impact of a warming climate on global isoprene emissions. Here we demonstrate that in the early successional species Vismia guianensis in the central Amazon, ETR rates increased with temperature in concert with isoprene emissions, even as stomatal conductance (gs ) and net photosynthetic carbon fixation (Pn ) declined. We observed the highest temperatures of continually increasing isoprene emissions yet reported (50°C). While Pn showed an optimum value of 32.6 ± 0.4°C, isoprene emissions, ETR, and the oxidation state of PSII reaction centers (qL ) increased with leaf temperature with strong linear correlations for ETR (ƿ = 0.98) and qL (ƿ = 0.99) with leaf isoprene emissions. In contrast, other photoprotective mechanisms, such as non-photochemical quenching, were not activated at elevated temperatures. Inhibition of isoprenoid biosynthesis repressed Pn at high temperatures through a mechanism that was independent of stomatal closure. While extreme warming will decrease gs and Pn in tropical species, our observations support a thermal tolerance mechanism where the maintenance of high photosynthetic capacity under extreme warming is assisted by the simultaneous stimulation of ETR and metabolic pathways that consume the direct products of ETR including photorespiration and the biosynthesis of thermoprotective isoprenoids. Our results confirm that models which link isoprene emissions to the rate of ETR hold true in tropical species and provide necessary "ground-truthing" for simulations of the large predicted increases in tropical isoprene emissions with climate warming.
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Affiliation(s)
- Tayana B Rodrigues
- Forest Management Laboratory, National Institute of Amazonian Research, Manaus, Brazil
| | - Christopher R Baker
- Howard Hughes Medical Institute, Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA
| | - Anthony P Walker
- Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Nate McDowell
- Earth System Analysis and Modeling, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Alistair Rogers
- Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton, NY, USA
| | - Niro Higuchi
- Forest Management Laboratory, National Institute of Amazonian Research, Manaus, Brazil
| | - Jeffrey Q Chambers
- Forest Management Laboratory, National Institute of Amazonian Research, Manaus, Brazil
- Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Kolby J Jardine
- Forest Management Laboratory, National Institute of Amazonian Research, Manaus, Brazil
- Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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7
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Halbritter AH, De Boeck HJ, Eycott AE, Reinsch S, Robinson DA, Vicca S, Berauer B, Christiansen CT, Estiarte M, Grünzweig JM, Gya R, Hansen K, Jentsch A, Lee H, Linder S, Marshall J, Peñuelas J, Kappel Schmidt I, Stuart‐Haëntjens E, Wilfahrt P, Vandvik V, Abrantes N, Almagro M, Althuizen IHJ, Barrio IC, te Beest M, Beier C, Beil I, Berry ZC, Birkemoe T, Bjerke JW, Blonder B, Blume‐Werry G, Bohrer G, Campos I, Cernusak LA, Chojnicki BH, Cosby BJ, Dickman LT, Djukic I, Filella I, Fuchslueger L, Gargallo‐Garriga A, Gillespie MAK, Goldsmith GR, Gough C, Halliday FW, Joar Hegland S, Hoch G, Holub P, Jaroszynska F, Johnson DM, Jones SB, Kardol P, Keizer JJ, Klem K, Konestabo HS, Kreyling J, Kröel‐Dulay G, Landhäusser SM, Larsen KS, Leblans N, Lebron I, Lehmann MM, Lembrechts JJ, Lenz A, Linstädter A, Llusià J, Macias‐Fauria M, Malyshev AV, Mänd P, Marshall M, Matheny AM, McDowell N, Meier IC, Meinzer FC, Michaletz ST, Miller ML, Muffler L, Oravec M, Ostonen I, Porcar‐Castell A, Preece C, Prentice IC, Radujković D, Ravolainen V, Ribbons R, Ruppert JC, Sack L, Sardans J, Schindlbacher A, Scoffoni C, Sigurdsson BD, Smart S, Smith SW, Soper F, Speed JDM, Sverdrup‐Thygeson A, Sydenham MAK, Taghizadeh‐Toosi A, Telford RJ, Tielbörger K, Töpper JP, Urban O, Ploeg M, Van Langenhove L, Večeřová K, Ven A, Verbruggen E, Vik U, Weigel R, Wohlgemuth T, Wood LK, Zinnert J, Zurba K. The handbook for standardized field and laboratory measurements in terrestrial climate change experiments and observational studies (ClimEx). Methods Ecol Evol 2019. [DOI: 10.1111/2041-210x.13331] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Aud H. Halbritter
- Department of Biological Sciences and Bjerknes Centre for Climate Research University of Bergen Bergen Norway
| | - Hans J. De Boeck
- Department of Biology Centre of Excellence PLECO (Plants and Ecosystems) Universiteit Antwerpen Wilrijk Belgium
| | - Amy E. Eycott
- Department of Biological Sciences University of Bergen Bergen Norway
- Faculty of Biosciences and Aquaculture Nord University Steinkjer Norway
| | - Sabine Reinsch
- Centre for Ecology & Hydrology Environment Centre Wales Bangor UK
| | | | - Sara Vicca
- Department of Biology Centre of Excellence PLECO (Plants and Ecosystems) Universiteit Antwerpen Wilrijk Belgium
| | - Bernd Berauer
- Department of Disturbance Ecology University of Bayreuth Bayreuth Germany
| | | | - Marc Estiarte
- CSIC Global Ecology Unit CREAF‐CSIC‐UAB Bellaterra Spain
- CREAF Vallès Spain
| | - José M. Grünzweig
- Institute of Plant Sciences and Genetics in Agriculture The Hebrew University of Jerusalem Rehovot Israel
| | - Ragnhild Gya
- Department of Biological Sciences and Bjerknes Centre for Climate Research University of Bergen Bergen Norway
| | - Karin Hansen
- Swedish Environmental Protection Agency Stockholm Sweden
- Swedish Environmental Research Institute IVL Stockholm Sweden
| | - Anke Jentsch
- Department of Disturbance Ecology University of Bayreuth Bayreuth Germany
| | - Hanna Lee
- NORCE Norwegian Research Centre and Bjerknes Centre for Climate Research Bergen Norway
| | - Sune Linder
- Southern Swedish Forest Research Centre Swedish University of Agricultural Sciences Alnarp Sweden
| | - John Marshall
- Department of Forest Ecology and Management Swedish University of Agricultural Sciences Umeå Sweden
| | - Josep Peñuelas
- CSIC Global Ecology Unit CREAF‐CSIC‐UAB Bellaterra Spain
- CREAF Vallès Spain
| | - Inger Kappel Schmidt
- Department of Geosciences and Natural Resource Management University of Copenhagen Frederiksberg Denmark
| | | | - Peter Wilfahrt
- Department of Disturbance Ecology University of Bayreuth Bayreuth Germany
| | - Vigdis Vandvik
- Department of Biological Sciences and Bjerknes Centre for Climate Research University of Bergen Bergen Norway
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8
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Fontes CG, Dawson TE, Jardine K, McDowell N, Gimenez BO, Anderegg L, Negrón-Juárez R, Higuchi N, Fine PVA, Araújo AC, Chambers JQ. Dry and hot: the hydraulic consequences of a climate change-type drought for Amazonian trees. Philos Trans R Soc Lond B Biol Sci 2018; 373:20180209. [PMID: 30297481 PMCID: PMC6178441 DOI: 10.1098/rstb.2018.0209] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/17/2018] [Indexed: 11/12/2022] Open
Abstract
How plants respond physiologically to leaf warming and low water availability may determine how they will perform under future climate change. In 2015-2016, an unprecedented drought occurred across Amazonia with record-breaking high temperatures and low soil moisture, offering a unique opportunity to evaluate the performances of Amazonian trees to a severe climatic event. We quantified the responses of leaf water potential, sap velocity, whole-tree hydraulic conductance (Kwt), turgor loss and xylem embolism, during and after the 2015-2016 El Niño for five canopy-tree species. Leaf/xylem safety margins (SMs), sap velocity and Kwt showed a sharp drop during warm periods. SMs were negatively correlated with vapour pressure deficit, but had no significant relationship with soil water storage. Based on our calculations of canopy stomatal and xylem resistances, the decrease in sap velocity and Kwt was due to a combination of xylem cavitation and stomatal closure. Our results suggest that warm droughts greatly amplify the degree of trees' physiological stress and can lead to mortality. Given the extreme nature of the 2015-2016 El Niño and that temperatures are predicted to increase, this work can serve as a case study of the possible impact climate warming can have on tropical trees.This article is part of a discussion meeting issue 'The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications'.
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Affiliation(s)
- Clarissa G Fontes
- Department of Integrative Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Todd E Dawson
- Department of Integrative Biology, University of California at Berkeley, Berkeley, CA 94720, USA
- Ecosystem Science Division, Department of Science, Policy and Management, Environmental University of California Berkeley, Berkeley, CA, USA
| | - Kolby Jardine
- Climate Science Department, Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Building 74, Berkeley, CA 94720, USA
- Ciências de Florestas Tropicais, Instituto Nacional de Pesquisas da Amazônia (INPA), Manaus-AM 69067-375, Brazil
| | - Nate McDowell
- Pacific Northwest National Laboratory, Richland, WA, USA
| | - Bruno O Gimenez
- Ciências de Florestas Tropicais, Instituto Nacional de Pesquisas da Amazônia (INPA), Manaus-AM 69067-375, Brazil
| | - Leander Anderegg
- Department of Integrative Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Robinson Negrón-Juárez
- Climate Science Department, Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Building 74, Berkeley, CA 94720, USA
| | - Niro Higuchi
- Ciências de Florestas Tropicais, Instituto Nacional de Pesquisas da Amazônia (INPA), Manaus-AM 69067-375, Brazil
| | - Paul V A Fine
- Department of Integrative Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Alessandro C Araújo
- Department of Global Ecology, Carnegie Institution for Science, 260 Panama St., Stanford, CA 94305, USA
- Embrapa Amazônia Oriental, Trav. Dr. Enéas Pinheiro, Belém, Pará 66095-100, Brazil
| | - Jeffrey Q Chambers
- Climate Science Department, Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Building 74, Berkeley, CA 94720, USA
- Department of Geography, University of California Berkeley, 507 McCone Hall #4740, Berkeley, CA 94720, USA
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9
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McDowell N, Allen CD, Anderson-Teixeira K, Brando P, Brienen R, Chambers J, Christoffersen B, Davies S, Doughty C, Duque A, Espirito-Santo F, Fisher R, Fontes CG, Galbraith D, Goodsman D, Grossiord C, Hartmann H, Holm J, Johnson DJ, Kassim AR, Keller M, Koven C, Kueppers L, Kumagai T, Malhi Y, McMahon SM, Mencuccini M, Meir P, Moorcroft P, Muller-Landau HC, Phillips OL, Powell T, Sierra CA, Sperry J, Warren J, Xu C, Xu X. Drivers and mechanisms of tree mortality in moist tropical forests. New Phytol 2018; 219:851-869. [PMID: 29451313 DOI: 10.1111/nph.15027] [Citation(s) in RCA: 164] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 12/19/2017] [Indexed: 05/22/2023]
Abstract
Tree mortality rates appear to be increasing in moist tropical forests (MTFs) with significant carbon cycle consequences. Here, we review the state of knowledge regarding MTF tree mortality, create a conceptual framework with testable hypotheses regarding the drivers, mechanisms and interactions that may underlie increasing MTF mortality rates, and identify the next steps for improved understanding and reduced prediction. Increasing mortality rates are associated with rising temperature and vapor pressure deficit, liana abundance, drought, wind events, fire and, possibly, CO2 fertilization-induced increases in stand thinning or acceleration of trees reaching larger, more vulnerable heights. The majority of these mortality drivers may kill trees in part through carbon starvation and hydraulic failure. The relative importance of each driver is unknown. High species diversity may buffer MTFs against large-scale mortality events, but recent and expected trends in mortality drivers give reason for concern regarding increasing mortality within MTFs. Models of tropical tree mortality are advancing the representation of hydraulics, carbon and demography, but require more empirical knowledge regarding the most common drivers and their subsequent mechanisms. We outline critical datasets and model developments required to test hypotheses regarding the underlying causes of increasing MTF mortality rates, and improve prediction of future mortality under climate change.
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Affiliation(s)
- Nate McDowell
- Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - Craig D Allen
- US Geological Survey, Fort Collins Science Center, New Mexico Landscapes Field Station, Los Alamos, NM, 87544, USA
| | - Kristina Anderson-Teixeira
- Center for Tropical Forest Science-Forest Global Earth Observatory, Smithsonian Tropical Research Institute, Washington, DC, 20036, USA
- Conservation Ecology Center, Smithsonian Conservation Biology Institute, National Zoological Park, Front Royal, VA, 22630, USA
| | - Paulo Brando
- Woods Hole Research Center, 149 Woods Hole Road, Falmouth, MA, 02450, USA
- Instituto de Pesquisa Ambiental de Amazonia, Lago Norte, Brasilia, Brazil
| | - Roel Brienen
- School of Geography, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Jeff Chambers
- Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Brad Christoffersen
- Department of Biology and School of Earth, Environmental and Marine Sciences, University of Texas Rio Grande Valley, Edinburg, TX, 78539, USA
| | - Stuart Davies
- Center for Tropical Forest Science-Forest Global Earth Observatory, Smithsonian Tropical Research Institute, Washington, DC, 20036, USA
| | - Chris Doughty
- SICCS, Northern Arizona University, Flagstaff, AZ, 86001, USA
| | - Alvaro Duque
- Departmento de Ciencias Forestales, Universidad Nacional de Columbia, Medellín, Columbia
| | | | - Rosie Fisher
- National Center for Atmospheric Research, Boulder, CO, 80305, USA
| | - Clarissa G Fontes
- Department of Integrative Biology, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - David Galbraith
- School of Geography, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Devin Goodsman
- Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | | | - Henrik Hartmann
- Department of Biogeochemical Processes, Max Plank Institute for Biogeochemistry, 07745, Jena, Germany
| | - Jennifer Holm
- Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | | | - Abd Rahman Kassim
- Geoinformation Programme, Forestry and Environment Division, Forest Research Institute Malaysia, Selangor, Malaysia
| | - Michael Keller
- International Institute of Tropical Forestry, USDA Jardin Botanico Sur, 1201 Calle Ceiba, San Juan, 00926, Puerto Rico
- Embrapa Agricultural Informatics, Parque Estacao Biologica, Brasilia DF, 70770, Brazil
- Jet Propulsion Laboratory, Pasadena, CA, 91109, USA
| | - Charlie Koven
- Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Lara Kueppers
- Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Energy and Resources Group, University of California, Berkeley, CA, 94720, USA
| | - Tomo'omi Kumagai
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, 7 Chome-3-1 Hongo, Bunkyo, Tokyo, 113-8654, Japan
| | - Yadvinder Malhi
- Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford, OX1 2JD, UK
| | - Sean M McMahon
- Center for Tropical Forest Science-Forest Global Earth Observatory, Smithsonian Tropical Research Institute, Washington, DC, 20036, USA
| | - Maurizio Mencuccini
- ICREA, CREAF, University of Barcelona, Gran Via de les Corts Catalenes, 585 08007, Barcelona, Spain
| | - Patrick Meir
- Australian National University, Acton, Canberra, ACT, 2601, Australia
- School of Geosciences, University of Edinburgh, Old College, South Bridge, Edinburgh, EH8 9YL, UK
| | | | - Helene C Muller-Landau
- Smithsonian Tropical Research Institute, Apartado Postal, 0843-03092, Panamá, República de Panamá
| | - Oliver L Phillips
- School of Geography, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Thomas Powell
- Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Carlos A Sierra
- Department of Biogeochemical Processes, Max Plank Institute for Biogeochemistry, 07745, Jena, Germany
| | - John Sperry
- University of Utah, Salt Lake City, UT, 84112, USA
| | - Jeff Warren
- Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Chonggang Xu
- Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Xiangtao Xu
- Department of Geosciences, Princeton University, Princeton, NJ, 08544, USA
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Anderegg WRL, Hicke JA, Fisher RA, Allen CD, Aukema J, Bentz B, Hood S, Lichstein JW, Macalady AK, McDowell N, Pan Y, Raffa K, Sala A, Shaw JD, Stephenson NL, Tague C, Zeppel M. Tree mortality from drought, insects, and their interactions in a changing climate. New Phytol 2015; 208:674-83. [PMID: 26058406 DOI: 10.1111/nph.13477] [Citation(s) in RCA: 254] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 04/23/2015] [Indexed: 05/20/2023]
Abstract
Climate change is expected to drive increased tree mortality through drought, heat stress, and insect attacks, with manifold impacts on forest ecosystems. Yet, climate-induced tree mortality and biotic disturbance agents are largely absent from process-based ecosystem models. Using data sets from the western USA and associated studies, we present a framework for determining the relative contribution of drought stress, insect attack, and their interactions, which is critical for modeling mortality in future climates. We outline a simple approach that identifies the mechanisms associated with two guilds of insects - bark beetles and defoliators - which are responsible for substantial tree mortality. We then discuss cross-biome patterns of insect-driven tree mortality and draw upon available evidence contrasting the prevalence of insect outbreaks in temperate and tropical regions. We conclude with an overview of tools and promising avenues to address major challenges. Ultimately, a multitrophic approach that captures tree physiology, insect populations, and tree-insect interactions will better inform projections of forest ecosystem responses to climate change.
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Affiliation(s)
- William R L Anderegg
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, 08540, USA
| | - Jeffrey A Hicke
- Department of Geography, University of Idaho, Moscow, ID, 83844, USA
| | - Rosie A Fisher
- National Center for Atmospheric Research, Boulder, CO, 80305, USA
| | - Craig D Allen
- US Geological Survey, Fort Collins Science Center, Jemez Mountains Field Station, Los Alamos, NM, 87544, USA
| | - Juliann Aukema
- National Center for Ecological Analysis and Synthesis, Santa Barbara, CA, 93117, USA
| | - Barbara Bentz
- USDA Forest Service, Rocky Mountain Research Station, Logan, UT, 84321, USA
| | - Sharon Hood
- Division of Biological Sciences, The University of Montana, Missoula, MT, 59812, USA
| | - Jeremy W Lichstein
- Department of Biology, University of Florida, Gainesville, FL, 32611, USA
| | - Alison K Macalady
- School of Geography and Development, University of Arizona, Tucson, AZ, 85712, USA
| | - Nate McDowell
- Earth and Environmental Sciences Division, Los Alamos National Lab, Los Alamos, NM, 87545, USA
| | - Yude Pan
- Northern Research Station, US Forest Service, Newtown Square, PA, 19073, USA
| | - Kenneth Raffa
- Department of Entomology, University of Wisconsin, Madison, WI, 53706, USA
| | - Anna Sala
- Division of Biological Sciences, The University of Montana, Missoula, MT, 59812, USA
| | - John D Shaw
- Rocky Mountain Research Station, US Forest Service, Ogden, UT, 84401, USA
| | - Nathan L Stephenson
- US Geological Survey, Western Ecological Research Center, 47050 Generals Highway No. 4, Three Rivers, CA, 93271, USA
| | - Christina Tague
- Bren School of Environmental Science and Management, University of California - Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Melanie Zeppel
- Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia
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11
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Franks PJ, Adams MA, Amthor JS, Barbour MM, Berry JA, Ellsworth DS, Farquhar GD, Ghannoum O, Lloyd J, McDowell N, Norby RJ, Tissue DT, von Caemmerer S. Sensitivity of plants to changing atmospheric CO2 concentration: from the geological past to the next century. New Phytol 2013; 197:1077-1094. [PMID: 23346950 DOI: 10.1111/nph.12104] [Citation(s) in RCA: 155] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2012] [Accepted: 11/15/2012] [Indexed: 05/05/2023]
Abstract
The rate of CO(2) assimilation by plants is directly influenced by the concentration of CO(2) in the atmosphere, c(a). As an environmental variable, c(a) also has a unique global and historic significance. Although relatively stable and uniform in the short term, global c(a) has varied substantially on the timescale of thousands to millions of years, and currently is increasing at seemingly an unprecedented rate. This may exert profound impacts on both climate and plant function. Here we utilise extensive datasets and models to develop an integrated, multi-scale assessment of the impact of changing c(a) on plant carbon dioxide uptake and water use. We find that, overall, the sensitivity of plants to rising or falling c(a) is qualitatively similar across all scales considered. It is characterised by an adaptive feedback response that tends to maintain 1 - c(i)/c(a), the relative gradient for CO(2) diffusion into the leaf, relatively constant. This is achieved through predictable adjustments to stomatal anatomy and chloroplast biochemistry. Importantly, the long-term response to changing c(a) can be described by simple equations rooted in the formulation of more commonly studied short-term responses.
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Affiliation(s)
- Peter J Franks
- Faculty of Agriculture and Environment, University of Sydney, Sydney, NSW, 2006, Australia
| | - Mark A Adams
- Faculty of Agriculture and Environment, University of Sydney, Sydney, NSW, 2006, Australia
| | - Jeffrey S Amthor
- Faculty of Agriculture and Environment, University of Sydney, Sydney, NSW, 2006, Australia
| | - Margaret M Barbour
- Faculty of Agriculture and Environment, University of Sydney, Sydney, NSW, 2006, Australia
| | - Joseph A Berry
- Department of Global Ecology, Carnegie Institution of Washington, 260 Panama Street, Stanford, CA, 94305, USA
| | - David S Ellsworth
- Hawkesbury Institute for the Environment, University of Western Sydney, Hawkesbury Campus, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Graham D Farquhar
- Research School of Biology, The Australian National University, Acton, ACT, 0200, Australia
| | - Oula Ghannoum
- Hawkesbury Institute for the Environment, University of Western Sydney, Hawkesbury Campus, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Jon Lloyd
- Centre for Tropical Environmental and Sustainability Science (TESS), School of Earth and Environmental Sciences, James Cook University, Cairns, Qld, 4878, Australia
- Earth and Biosphere Institute, School of Geography, University of Leeds, Leeds, UK
| | - Nate McDowell
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Richard J Norby
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - David T Tissue
- Hawkesbury Institute for the Environment, University of Western Sydney, Hawkesbury Campus, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Susanne von Caemmerer
- Research School of Biology, The Australian National University, Acton, ACT, 0200, Australia
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Abstract
AIM To evaluate the efficacy and safety of continuous subcutaneous insulin infusion (CSII), and its impact on glycaemic control, insulin doses and auxological parameters in children with diabetes over a 4-year period. METHOD A retrospective analysis of all patients treated with CSII. Data on HbA1c, height, weight, insulin doses, hypoglycaemia and diabetic ketoacidosis (DKA) were analysed. RESULTS 67 patients, aged 1-16 years showed a mean (±SD) HbA1c pre-CSII of 8.2%, decreasing to 7.3% (±0.8%) at 6 months (p<0.01), 7.7% (±0.99) at 2 years (p<0.05), 7.4% (±0.94) at 3 years (n=9, p=0.15) and 7.6% (±0.97) at 4 years (n=4, p=1.0). Insulin doses reduced significantly with a trend towards reduced BMI SDS. Nine preschool children showed HbA1c reduction from 8.4% (±0.94) to 7.4% (±0.32, p<0.01) over 20 months with no episodes of severe hypoglycaemia or DKA. CONCLUSION The authors demonstrate that CSII is associated with significantly improved sustained glycaemic control, especially in preschool children with diabetes in motivated families.
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Affiliation(s)
- C R Hughes
- Diabetes Centre, Our Lady’s Children’s Hospital, Dublin, Ireland
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13
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Fisher R, McDowell N, Purves D, Moorcroft P, Sitch S, Cox P, Huntingford C, Meir P, Woodward FI. Assessing uncertainties in a second-generation dynamic vegetation model caused by ecological scale limitations. New Phytol 2010; 187:666-81. [PMID: 20618912 DOI: 10.1111/j.1469-8137.2010.03340.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
*Second-generation Dynamic Global Vegetation Models (DGVMs) have recently been developed that explicitly represent the ecological dynamics of disturbance, vertical competition for light, and succession. Here, we introduce a modified second-generation DGVM and examine how the representation of demographic processes operating at two-dimensional spatial scales not represented by these models can influence predicted community structure, and responses of ecosystems to climate change. *The key demographic processes we investigated were seed advection, seed mixing, sapling survival, competitive exclusion and plant mortality. We varied these parameters in the context of a simulated Amazon rainforest ecosystem containing seven plant functional types (PFTs) that varied along a trade-off surface between growth and the risk of starvation induced mortality. *Varying the five unconstrained parameters generated community structures ranging from monocultures to equal co-dominance of the seven PFTs. When exposed to a climate change scenario, the competing impacts of CO(2) fertilization and increasing plant mortality caused ecosystem biomass to diverge substantially between simulations, with mid-21st century biomass predictions ranging from 1.5 to 27.0 kg C m(-2). *Filtering the results using contemporary observation ranges of biomass, leaf area index (LAI), gross primary productivity (GPP) and net primary productivity (NPP) did not substantially constrain the potential outcomes. We conclude that demographic processes represent a large source of uncertainty in DGVM predictions.
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Affiliation(s)
- Rosie Fisher
- Earth and Environmental Science Division, Los Alamos National Laboratory, Los Alamos, NM, USA.
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14
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Uehlein N, Otto B, Hanson DT, Fischer M, McDowell N, Kaldenhoff R. Function of Nicotiana tabacum aquaporins as chloroplast gas pores challenges the concept of membrane CO2 permeability. Plant Cell 2008; 20:648-57. [PMID: 18349152 PMCID: PMC2329941 DOI: 10.1105/tpc.107.054023] [Citation(s) in RCA: 207] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Revised: 02/05/2008] [Accepted: 02/21/2008] [Indexed: 05/19/2023]
Abstract
Photosynthesis is often limited by the rate of CO(2) diffusion from the atmosphere to the chloroplast. The primary resistances for CO(2) diffusion are thought to be at the stomata and at photosynthesizing cells via a combination resulting from resistances of aqueous solution as well as the plasma membrane and both outer and inner chloroplast membranes. In contrast with stomatal resistance, the resistance of biological membranes to gas transport is not widely recognized as a limiting factor for metabolic function. We show that the tobacco (Nicotiana tabacum) plasma membrane and inner chloroplast membranes contain the aquaporin Nt AQP1. RNA interference-mediated decreases in Nt AQP1 expression lowered the CO(2) permeability of the inner chloroplast membrane. In vivo data show that the reduced amount of Nt AQP1 caused a 20% change in CO(2) conductance within leaves. Our discovery of CO(2) aquaporin function in the chloroplast membrane opens new opportunities for mechanistic examination of leaf internal CO(2) conductance regulation.
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Affiliation(s)
- Norbert Uehlein
- Department of Applied Plant Sciences, Institute of Botany, Darmstadt University of Technology, D-64287 Darmstadt, Germany.
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15
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McDowell N, Pockman WT, Allen CD, Breshears DD, Cobb N, Kolb T, Plaut J, Sperry J, West A, Williams DG, Yepez EA. Mechanisms of plant survival and mortality during drought: why do some plants survive while others succumb to drought? New Phytol 2008; 178:719-739. [PMID: 18422905 DOI: 10.1111/j.1469-8137.2008.02436.x] [Citation(s) in RCA: 1475] [Impact Index Per Article: 92.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Severe droughts have been associated with regional-scale forest mortality worldwide. Climate change is expected to exacerbate regional mortality events; however, prediction remains difficult because the physiological mechanisms underlying drought survival and mortality are poorly understood. We developed a hydraulically based theory considering carbon balance and insect resistance that allowed development and examination of hypotheses regarding survival and mortality. Multiple mechanisms may cause mortality during drought. A common mechanism for plants with isohydric regulation of water status results from avoidance of drought-induced hydraulic failure via stomatal closure, resulting in carbon starvation and a cascade of downstream effects such as reduced resistance to biotic agents. Mortality by hydraulic failure per se may occur for isohydric seedlings or trees near their maximum height. Although anisohydric plants are relatively drought-tolerant, they are predisposed to hydraulic failure because they operate with narrower hydraulic safety margins during drought. Elevated temperatures should exacerbate carbon starvation and hydraulic failure. Biotic agents may amplify and be amplified by drought-induced plant stress. Wet multidecadal climate oscillations may increase plant susceptibility to drought-induced mortality by stimulating shifts in hydraulic architecture, effectively predisposing plants to water stress. Climate warming and increased frequency of extreme events will probably cause increased regional mortality episodes. Isohydric and anisohydric water potential regulation may partition species between survival and mortality, and, as such, incorporating this hydraulic framework may be effective for modeling plant survival and mortality under future climate conditions.
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Affiliation(s)
- Nate McDowell
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - William T Pockman
- Department of Biology, MSC03 2020, 1 University of New Mexico, Albuquerque, NM 87131-0001, USA
| | - Craig D Allen
- US Geologcial Survey, Jemez Mountains Field Station, 15 Entrance Road, Los Alamos, NM 87544, USA
| | - David D Breshears
- School of Natural Resources, Institute for the Study of Planet Earth, and Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721-0043, USA
| | - Neil Cobb
- Merriam-Powell Center for Environmental Research, Peterson Hall, Bldg 22, Rm 330, Box 6077, Northern Arizona University Flagstaff, AZ 86011, USA
| | - Thomas Kolb
- School of Forestry, Northern Arizona University, Flagstaff, AZ 86001-5018, USA
| | - Jennifer Plaut
- Department of Biology, MSC03 2020, 1 University of New Mexico, Albuquerque, NM 87131-0001, USA
| | - John Sperry
- Department of Biology, University of Utah, 257S 1400E, Salt Lake City, UT 84112, USA
| | - Adam West
- Department of Integrative Biology, University of California, Berkeley, CA 94720
- Botany Department, University of Cape Town, Private Bag, Rondebosch, 7700, South Africa
| | - David G Williams
- Department of Renewable Resources, University of Wyoming, Laramie, WY 82071 USA
| | - Enrico A Yepez
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA
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McDowell N, Baldocchi D, Barbour M, Bickford C, Cuntz M, Hanson D, Knohl A, Powers H, Rahn T, Randerson J, Riley WJ, Still C, Tu K, Walcroft A. Understanding the Stable Isotope Composition of Biosphere-Atmosphere CO2Exchange. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2008eo100002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
BACKGROUND Clinical and experimental data suggest that certain dietary regimens, particularly those including polyunsaturated fatty acids (PUFAs) and vitamins might improve outcomes in people with multiple sclerosis (MS). Diets and dietary supplements are much used by people with MS in the belief that they might improve disease outcomes. OBJECTIVES We performed a Cochrane review of all randomised trials of dietary regimens for MS with the aim of answering MS consumers' questions regarding the efficacy and safety of these interventions. SEARCH STRATEGY We searched the Cochrane MS Group trial register (February 2006), Cochrane Central Register of Controlled Trials (CENTRAL), Cochrane Library, Issue 1, 2006, MEDLINE (PubMed) (1966 to March 2006), EMBASE (1974 to March 2006) and the bibliographies of papers found. SELECTION CRITERIA All randomised controlled trials comparing a specific dietary intervention, diet plan or dietary supplementation, with no dietary modification or placebo, were eligible. DATA COLLECTION AND ANALYSIS Two reviewers independently selected articles, assessed trial quality and extracted data. Trial quality was poor, particularly as regards descriptions of randomisation, blinding and adverse event reporting. Some studies had large numbers of drop-outs; dropouts were never included in the analyses. MAIN RESULTS PUFAs did not have a significant effect on disease progression, measured as worsening of Disability Status Scale. Omega-6 fatty acids (11-23 g/day linoleic acid) had no benefit in 75 relapsing remitting (RR) MS patients (progression at two years: relative risk (RR)=0.78, 95% CI [0.45 to 1.36]) or in 69 chronic progressive (CP) MS patients (RR=1.67, 95% CI [0.75 to 3.72]. Linoleic acid (2.9-3.4 g/day) had no benefit in CPMS (progression at two years: RR=0.78, 95% CI [0.43 to 1.42]). Slight decreases in relapse rate and relapse severity were associated with omega-6 fatty acids in some small studies, however these findings are limited by the limited validity of the endpoints.Omega-3 fatty acids had no benefit on progression at 12 months in 14 RRMS patients or at 24 months in 292 RRMS patients (RR=0.15, 95% CI [0.01 to 3.11], p= 0.22 at 12 months, and 0.82 95% CI [0.65 to 1.03], p=0.08, at 24 months). The low frequency of reported adverse events suggests no major toxicity associated with PUFA administration. No studies on vitamin supplementation and allergen-free diets were analysed as none met the eligibility criteria. AUTHORS' CONCLUSIONS PUFAs seem to have no major effect on the main clinical outcome in MS (disease progression), and does not substantially affect the risk of clinical relapses over 2 years. However, the data available are insufficient to assess any potential benefit or harm from PUFA supplementation. Evidence bearing on the possible benefits and risks of vitamin supplementation and antioxidant supplements in MS is lacking. More research is required to assess the effectiveness of diets interventions in MS.
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Affiliation(s)
- M Farinotti
- Istituto Nazionale Neurologico Carlo Besta, S.O. Neuroepidemiologia, via Celoria 11, Milano (MI), Italy, 20133.
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Flexas J, Ribas-Carbó M, Hanson DT, Bota J, Otto B, Cifre J, McDowell N, Medrano H, Kaldenhoff R. Tobacco aquaporin NtAQP1 is involved in mesophyll conductance to CO2 in vivo. Plant J 2006; 48:427-39. [PMID: 17010114 DOI: 10.1111/j.1365-313x.2006.02879.x] [Citation(s) in RCA: 266] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Leaf mesophyll conductance to CO(2) (g(m)) has been recognized to be finite and variable, rapidly adapting to environmental conditions. The physiological basis for fast changes in g(m) is poorly understood, but current reports suggest the involvement of protein-facilitated CO(2) diffusion across cell membranes. A good candidate for this could be the Nicotiana tabacum L. aquaporin NtAQP1, which was shown to increase membrane permeability to CO(2) in Xenopus oocytes. The objective of the present work was to evaluate its effect on the in vivo mesophyll conductance to CO(2), using plants either deficient in or overexpressing NtAQP1. Antisense plants deficient in NtAQP1 (AS) and NtAQP1 overexpressing tobacco plants (O) were compared with their respective wild-type (WT) genotypes (CAS and CO). Plants grown under optimum conditions showed different photosynthetic rates at saturating light, with a decrease of 13% in AS and an increase of 20% in O, compared with their respective controls. CO(2) response curves of photosynthesis also showed significant differences among genotypes. However, in vitro analysis demonstrated that these differences could not be attributed to alterations in Rubisco activity or ribulose-1,5-bisphosphate content. Analyses of chlorophyll fluorescence and on-line (13)C discrimination indicated that the observed differences in net photosynthesis (A(N)) among genotypes were due to different leaf mesophyll conductances to CO(2), which was estimated to be 30% lower in AS and 20% higher in O compared with their respective WT. These results provide evidence for the in vivo involvement of aquaporin NtAQP1 in mesophyll conductance to CO(2).
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Affiliation(s)
- Jaume Flexas
- Laboratori de Fisiologia Vegetal, Grup de Biologia de les Plantes en Condicions Mediterrànies, Universitat de les Illes Balears. Carretera de Valldemossa Km 7.5, 07122 Palma de Mallorca, Balears, Spain.
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20
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Abstract
We present an approach that sets limits on annual carbon fluxes for different aged forests by using a simple process-based model (3-PG) and information derived from yield tables and local weather stations. Given a measure of height-growth potential, model predictions are constrained to match stand dynamics described in yield tables. Thus constrained, the model can provide reasonable annual estimates of gross photosynthesis under a specified climate, even with inexact knowledge of soil properties. If we assume that leaf litterfall and fine-root turnover approach equilibrium at canopy closure, maximum net annual ecosystem exchange can also be predicted from modeled estimates of these two detrital components and estimates of foliage, branch, stem and coarse-root production. The latter four components of production are predicted from allometric relationships with mean stem diameter. The approach is demonstrated for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands between Ages 20 and 150 years growing under conditions typical of those at Wind River, Washington, USA. Gross photosynthesis (Pg) by Douglas-fir at Ages 20, 70 and 150 years with leaf area indices (L) of 8.1, 6.9 and 4.0 was predicted at 1630, 1580 and 1160 g C m-2 year(1, respectively. Maximum net ecosystem production (Pe) for the same range in age classes was predicted to average 275, 294 and 207 g C m-2 year-1, respectively. The predicted reductions in L for older stands do not occur because other species fill the canopy gaps created by natural mortality of Douglas-fir. As a result of the development of an understory, total Pg is predicted to decrease only slightly with the aging of the overstory. Estimates of Pe exclude respiration from coarse woody debris, although additions of this component are provided annually by the model. The process-based modeling approach, constrained by yield table estimates of stand properties, sets reasonable limits on annual carbon exchange and suggests which environmental variables deserve careful monitoring to refine estimates of carbon fluxes.
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Affiliation(s)
- R H Waring
- College of Forestry, Oregon State University, Corvallis, OR 97331, USA.
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McDowell N, Gurdon JB, Grainger DJ. Formation of a functional morphogen gradient by a passive process in tissue from the early Xenopus embryo. Int J Dev Biol 2001; 45:199-207. [PMID: 11291847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
In early development much of the cellular diversity and pattern formation of the embryo is believed to be set up by morphogens. However, for many morphogens, including members of the TGF-beta superfamily, the mechanism(s) by which they reach distant cells is unknown. We have used immunofluorescence to detect, at single cell resolution, a morphogen gradient formed across vertebrate tissue. The TGF-beta ligand is distributed in a gradient visible up to 7 cell diameters (about 150-200 microm) from its source, and is detectable only in the extracellular space. This morphogen gradient is functional, since we demonstrate activation of a high response gene (Xeomes) and a low-response gene (Xbra) at different distances from the TGF-beta source. Expression of the high affinity type II TGF-beta receptor is necessary for detection of the gradient, but the shape of the gradient formed only depends in part on the spatial variation in the amount of receptor. Finally, we demonstrate that the molecular processes that participate in forming this functional morphogen gradient are temperature independent, since the gradient forms to a similar extent whether the cells are maintained at 4 degrees C or 23 degrees C. In contrast, TGF-beta1 internalisation by cells of the Xenopus embryo is a temperature-dependent process. Our results thus suggest that neither vesicular transcytosis nor other active processes contribute to a significant extent to the formation of the morphogen gradient we observe. We conclude that, in the model system used here, a functional morphogen gradient can be formed within a few hours by a mechanism of passive diffusion.
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Affiliation(s)
- N McDowell
- Wellcome/CRC Institute of Cancer and Developmental Biology, Cambridge, England
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22
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Abstract
Activin, a member of the Transforming Growth Factor beta (TGF-beta) superfamily, can behave as a morphogen in cells of the early Xenopus embryo by inducing a range of mesodermal genes in a concentration-dependent manner. This review examines the behaviour of activin as it forms a morphogen gradient. It also discusses how a cell can perceive its position in a concentration gradient in order to activate appropriate mesodermal gene responses.
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Affiliation(s)
- N McDowell
- Wellcome/CRC Institute of Cancer and Developmental Biology, Tennis Court Road, Cambridge, CB2 1QR, UK
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23
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Abstract
OBJECTIVE To examine the promotion of physical activity by general practitioners (GPs) and practice nurses (PNs). METHODS A questionnaire that examined the types of barriers and the levels of their influence as well as stage of change for activity promotion and for personal behaviour was mailed to 846 subjects. RESULTS The return rate exceeded 70% in each group with a high proportion (69%) of GPs and PNs reporting that they regularly promote physical activity with their patients. GPs were less likely to regularly promote physical activity with their patients if they indicated lack of time as a barrier (odds ratio (OR) = 0.73, 95% confidence interval (CI) 0.58 to 0.93) or lack of incentives (OR = 0.74, 95% CI 0.59 to 0.94), and more likely to promote exercise if they themselves were regular exercisers (OR = 3.19, 95% CI 1.96 to 5.18). However, for PNs longer consultation times (by 1.5 to 2 minutes) had a higher likelihood of producing regular promotion of activity (OR = 1.61, 95% CI 1.02 to 1.62). For PNs personal physical activity stage was the strongest significant predictor of promotion level, but with a stronger effect (OR = 4.77, 95% CI 1.48 to 15.35) than in the GPs. CONCLUSION The main finding is that GPs in the action or maintenance stage of changing their own physical activity are three times more likely to regularly promote the same behaviour in their patients than those in the other stages; for PNs the same difference quadruples the likelihood of them promoting physical activity. Professional readiness to change is influenced by known system barriers in GPs, and not in PNs, but is more strongly predicted by personal physical activity behaviour in both groups.
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Affiliation(s)
- J McKenna
- Exercise and Health Research Unit, University of Bristol, United Kingdom
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Gurdon JB, Ryan K, Stennard F, McDowell N, Zorn AM, Crease DJ, Dyson S. Cell response to different concentrations of a morphogen: activin effects on Xenopus animal caps. Cold Spring Harb Symp Quant Biol 1998; 62:151-8. [PMID: 9598347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- J B Gurdon
- Wellcome CRC Institute, Cambridge, England
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25
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Abstract
OBJECTIVE To investigate what factors may influence practice nurses to promote physical activity. METHODS Postal questionnaires were sent to all practice nurses in the county of Avon, UK in 1994. Specifically, the questionnaire survey explored whether patient, provider, and practice factors influenced practice nurses promotion behaviour. In addition, the stages of change model was used to measure current levels of promoting behaviour. RESULTS A response rate of 80.9% was achieved. Over 80% of the sample reported currently promoting physical activity to some degree. "Promoting" nurses more frequently followed up all (new, established or targeted) patients' activity progress when compared with "restricted promoting" nurses (P < 0.05). Nurses who engaged in regular exercise were more likely to encourage physical activity as a treatment than "irregularly active" nurses (P < 0.05) for five of six clinical groups with the single exception of people with diabetes. CONCLUSIONS This study shows that the two stage measures (activity promotion and personal behaviour) of the health care professional are associated with important differences in patient and practice factors for physical activity promotion. Further investigations into the content and quality of delivery are required before planning strategies to develop physical activity in the general practice.
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Affiliation(s)
- N McDowell
- School of Physiotherapy and Occupational Therapy, University of the West of England, Bristol
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26
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Abstract
BACKGROUND Activin has strong mesoderm-inducing properties in the early Xenopus embryo, and has a long-range signalling activity that activates genes in cells distant from a source in a concentration-dependent way. It has not yet been established what mechanism of signal transmission accounts for this and other examples of long-range signalling in vertebrates. Nor is it known whether activin itself acts on distant cells or whether other kinds of molecules are used for long-range signalling. Here we have used a well characterised model system, involving animal caps of Xenopus blastulae treated with activin or transforming growth factor beta, to analyze some fundamental properties of long-range signalling and of the formation of a morphogen gradient. RESULTS We find that cells distant from the source of activin require functional activin receptors to activate Xbrachyury, a result suggesting that activin itself acts directly on distant cells and that other secondary signalling molecules are not required. We also find that the signals can be transmitted across a tissue that cannot respond to it; this argues against a relay process. We provide direct evidence that labelled activin forms a concentration gradient emanating from its source and extending to the distant cells that express Xbrachyury. Lastly, we show that there is no inherent polarity in the responding tissue that influences either the direction or rate of signalling. CONCLUSIONS The long-range signalling mechanism by which activin initiates the transcription of genes in a concentration-dependent manner depends on a process of rapid diffusion and the establishment of an activin gradient across the tissue. It cannot be explained by a relay or wave propagation mechanism. Activin itself is the signalling molecule to which distant cells respond.
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Affiliation(s)
- N McDowell
- Wellcome CRC Institute of Cancer and Developmental Biology, Tennis Court Road, Cambridge, CB2 1QR, UK
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27
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Gurdon JB, Ryan K, Stennard F, McDowell N, Crease D, Dyson S, Zorn A, Garrett N, Mitchell A, Carnac G. Long range signalling process in embryonic development. Int J Dev Biol 1996; Suppl 1:57S-58S. [PMID: 9087695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- J B Gurdon
- Wellcome CRC Institute, Cambridge, England
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