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  • 1. Atkin, Owen K
    et al.
    Atkinson, Lindsey J
    Fischer, Rosie A
    Campbell, Catherine
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Zaragoza-Castells, Joana
    Pitchford, Jon W
    Woodward, F Ian
    Hurry, Vaughan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Using temperature-dependent changes in leaf scaling relationships to quantitatively account forthermal acclimation of respiration in a coupled global climate-vegetation model2008Inngår i: Global Change Biology, Vol. 14, s. 2709-2726Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [sv]

    The response of plant respiration (R) to temperature is an important component of the biosphere's response to climate change. At present, most global models assume that R increases exponentially with temperature and does not thermally acclimate. Although we now know that acclimation does occur, quantitative incorporation of acclimation into models has been lacking. Using a dataset for 19 species grown at four temperatures (7, 14, 21, and 28 °C), we have assessed whether sustained differences in growth temperature systematically alter the slope and/or intercepts of the generalized log–log plots of leaf R vs. leaf mass per unit leaf area (LMA) and vs. leaf nitrogen (N) concentration. The extent to which variations in growth temperature account for the scatter observed in log–log R–LMA–N scaling relationships was also assessed. We show that thermal history accounts for up to 20% of the scatter in scaling relationships used to predict R, with the impact of thermal history on R–LMA–N generalized scaling relationships being highly predictable. This finding enabled us to quantitatively incorporate acclimation of R into a coupled global climate–vegetation model. We show that accounting for acclimation of R has negligible impact on predicted annual rates of global R, net primary productivity (NPP) or future atmospheric CO2 concentrations. However, our analysis suggests that accounting for acclimation is important when considering carbon fluxes among thermally contrasting biomes (e.g. accounting for acclimation decreases predicted rates of R by up to 20% in high-temperature biomes). We conclude that acclimation of R needs to be accounted for when predicting potential responses of terrestrial carbon exchange to climatic change at a regional level.

  • 2.
    Atkin, Owen K
    et al.
    Department of Biology, The University of York, PO Box 373, York YO10 5YW, UK.
    Sherlock, David
    Department of Biology, The University of York, PO Box 373, York YO10 5YW, UK.
    Fitter, Alastair H
    Department of Biology, The University of York, PO Box 373, York YO10 5YW, UK.
    Jarvis, Susan
    Department of Biology, The University of York, PO Box 373, York YO10 5YW, UK.
    Hughes, John K
    Department of Biology, The University of York, PO Box 373, York YO10 5YW, UK.
    Campbell, Catherine
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Hurry, Vaughan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Hodge, Angela
    Department of Biology, The University of York, PO Box 373, York YO10 5YW, UK.
    Temperature dependence of respiration in roots colonized by arbuscular mycorrhizal fungi2009Inngår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 182, nr 1, s. 188-199Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    * The arbuscular mycorrhizal (AM) symbiosis is ubiquitous, and the fungus represents a major pathway for carbon movement in the soil-plant system. Here, we investigated the impacts of AM colonization of Plantago lanceolata and temperature on the regulation of root respiration (R). * Warm-grown AM plants exhibited higher rates of R than did nonAM plants, irrespective of root mass. AM plants exhibited higher maximal rates of R (R(max)-R measured in the presence of an uncoupler and exogenous substrate) and greater proportional use of R(max) as a result of increased energy demand and/or substrate supply. The higher R values exhibited by AM plants were not associated with higher maximal rates of cytochrome c oxidase (COX) or protein abundance of either the COX or the alternative oxidase. * Arbuscular mycorrhizal colonization had no effect on the short-term temperature dependence (Q(10)) of R. Cold-acclimated nonAM plants exhibited higher rates of R than their warm-grown nonAM counterparts. By contrast, chilling had a negligible effect on R of AM-plants. Thus, AM plants exhibited less cold acclimation than their nonAM counterparts. * Overall, these results highlight the way in which AM colonization alters the underlying components of respiratory metabolism and the response of root R to sustained changes in growth temperature.

  • 3. Atkinson, Lindsey J
    et al.
    Campbell, Catherine D
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Zaragoza-Castells, Joana
    Hurry, Vaughan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Atkin, Owen K
    Impact of growth temperature on scaling relationships linking photosynthetic metabolism to leaf functional traits2010Inngår i: Functional Ecology, ISSN 0269-8463, E-ISSN 1365-2435, Vol. 24, nr 6, s. 1181-1191Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    1. Scaling relationships linking photosynthesis (A) to leaf traits are important for predicting vegetation patterns and plant-atmosphere carbon fluxes. Here, we investigated the impact of growth temperature on such scaling relationships.

    2. We assessed whether changes in growth temperature systematically altered the slope and/or intercepts of log-log plots of A vs leaf mass per unit leaf area (LMA), nitrogen and phosphorus concentrations for 19 contrasting plant species grown hydroponically at four temperatures (7, 14, 21 and 28 degrees C) in controlled environment cabinets. Responses of 21 degrees C-grown pre-existing (PE) leaves experiencing a 10 day growth temperature (7, 14, 21 and 28 degrees C) treatment, and newly-developed (ND) leaves formed at each of the four new growth temperatures, were quantified. Irrespective of the growth temperature treatment, rates of light-saturated photosynthesis (A) were measured at 21 degrees C.

    3. Changes in growth temperature altered the scaling between A and leaf traits in pre-existing (PE) leaves, with thermal history accounting for up to 17% and 31% of the variation on a mass and area basis, respectively. However, growth temperature played almost no role in accounting for scatter when comparisons were made of newly-developed (ND) leaves that form at each growth temperature.

    4. Photosynthetic nitrogen and phosphorus use efficiency (PNUE and PPUE, respectively) decreased with increasing LMA. No systematic differences in temperature-mediated reductions in PNUE or PPUE of PE leaves were found among species.

    5. Overall, these results highlight the importance of leaf development in determining the effects of sustained changes in growth temperature on scaling relationships linking photosynthesis to other leaf traits.

  • 4. Campbell, Catherine
    et al.
    Atkinson, Lindsey
    Zaragoza-Castells, Joana
    Lundmark, Maria
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Atkin, Owen
    Hurry, Vaughan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Acclimation of photosynthesis and respiration in response to change in growth temperature is asynchronous across plant functional groups2007Inngår i: New Phytologist, ISSN 0028-646XArtikkel i tidsskrift (Fagfellevurdert)
  • 5. Hogberg, Mona N.
    et al.
    Briones, Maria J. I.
    Keel, Sonja G.
    Metcalfe, Daniel B.
    Campbell, Catherine
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Midwood, Andrew J.
    Thornton, Barry
    Hurry, Vaughan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Linder, Sune
    Nasholm, Torgny
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Hogberg, Peter
    Quantification of effects of season and nitrogen supply on tree below-ground carbon transfer to ectomycorrhizal fungi and other soil organisms in a boreal pine forest2010Inngår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 187, nr 2, s. 485-493Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    P>The flux of carbon from tree photosynthesis through roots to ectomycorrhizal (ECM) fungi and other soil organisms is assumed to vary with season and with edaphic factors such as nitrogen availability, but these effects have not been quantified directly in the field. To address this deficiency, we conducted high temporal-resolution tracing of 13C from canopy photosynthesis to different groups of soil organisms in a young boreal Pinus sylvestris forest. There was a 500% higher below-ground allocation of plant C in the late (August) season compared with the early season (June). Labelled C was primarily found in fungal fatty acid biomarkers (and rarely in bacterial biomarkers), and in Collembola, but not in Acari and Enchytraeidae. The production of sporocarps of ECM fungi was totally dependent on allocation of recent photosynthate in the late season. There was no short-term (2 wk) effect of additions of N to the soil, but after 1 yr, there was a 60% reduction of below-ground C allocation to soil biota. Thus, organisms in forest soils, and their roles in ecosystem functions, appear highly sensitive to plant physiological responses to two major aspects of global change: changes in seasonal weather patterns and N eutrophication.

  • 6. Högberg, Peter
    et al.
    Högberg, M. N.
    Göttlicher, S. G.
    Betson, N. R.
    Keel, S. G.
    Metcalfe, D. B.
    Campbell, Catherine
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Schindlbacher, A.
    Hurry, Vaughan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Lundmark, Thomas
    Linder, Sune
    Näsholm, Torgny
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    High temporal resolution tracing of photosynthate carbon from the tree canopy to forest soil microorganisms2008Inngår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 177, nr 1, s. 220-228Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    • Half of the biological activity in forest soils is supported by recent tree photosynthate, but no study has traced in detail this flux of carbon from the canopy to soil microorganisms in the field.

    • Using 13CO2, we pulse-labelled over 1.5 h a 50-m2 patch of 4-m-tall boreal Pinus sylvestris forest in a 200-m3 chamber.

    • Tracer levels peaked after 24 h in soluble carbohydrates in the phloem at a height of 0.3 m, after 2–4 d in soil respiratory efflux, after 4–7 d in ectomycorrhizal roots, and after 2–4 d in soil microbial cytoplasm. Carbon in the active pool in needles, in soluble carbohydrates in phloem and in soil respiratory efflux had half-lives of 22, 17 and 35 h, respectively. Carbon in soil microbial cytoplasm had a half-life of 280 h, while the carbon in ectomycorrhizal root tips turned over much more slowly. Simultaneous labelling of the soil with showed that the ectomycorrhizal roots, which were the strongest sinks for photosynthate, were also the most active sinks for soil nitrogen.

    • These observations highlight the close temporal coupling between tree canopy photosynthesis and a significant fraction of soil activity in forests.

  • 7. Keel, Sonja G.
    et al.
    Campbell, Catherine D.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Hogberg, Mona N.
    Richter, Andreas
    Wild, Birgit
    Zhou, Xuhui
    Hurry, Vaughan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Linder, Sune
    Nasholm, Torgny
    Hogberg, Peter
    Allocation of carbon to fine root compounds and their residence times in a boreal forest depend on root size class and season2012Inngår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 194, nr 4, s. 972-981Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fine roots play a key role in the forest carbon balance, but their carbon dynamics remain largely unknown. We pulse labelled 50 m2 patches of young boreal forest by exposure to 13CO2 in early and late summer. Labelled photosynthates were traced into carbon compounds of < 1 and 13 mm diameter roots (fine roots), and into bulk tissue of these and first-order roots (root tips). Root tips were the most strongly labelled size class. Carbon allocation to all size classes was higher in late than in early summer; mean residence times (MRTs) in starch increased from 4 to 11 months. In structural compounds, MRTs were 0.8 yr in tips and 1.8 yr in fine roots. The MRT of carbon in sugars was in the range of days. Functional differences within the fine root population were indicated by carbon allocation patterns and residence times. Pronounced allocation of recent carbon and higher turnover rates in tips are associated with their role in nutrient and water acquisition. In fine roots, longer MRTs but high allocation to sugars and starch reflect their role in structural support and storage. Accounting for heterogeneity in carbon residence times will improve and most probably reduce the estimates of fine root production.

  • 8. Metcalfe, Daniel B.
    et al.
    Lobo-do-Vale, Raquel
    Chaves, Manuela M.
    Maroco, Joao P.
    Aragao, Luiz E. O. C.
    Malhi, Yadvinder
    Da Costa, Antonio L.
    Braga, Alan P.
    Goncalves, Paulo L.
    De Athaydes, Joao
    Da Costa, Mauricio
    Almeida, Samuel S.
    Campbell, Catherine
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Hurry, Vaughan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Williams, Mathew
    Meir, Patrick
    Impacts of experimentally imposed drought on leaf respiration and morphology in an Amazon rain forest2010Inngår i: Functional Ecology, ISSN 0269-8463, E-ISSN 1365-2435, Vol. 24, nr 3, s. 524-533Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    P>1. The Amazon region may experience increasing moisture limitation over this century. Leaf dark respiration (R) is a key component of the Amazon rain forest carbon (C) cycle, but relatively little is known about its sensitivity to drought. 2. Here, we present measurements of R standardized to 25 degrees C and leaf morphology from different canopy heights over 5 years at a rain forest subject to a large-scale through-fall reduction (TFR) experiment, and nearby, unmodified Control forest, at the Caxiuana reserve in the eastern Amazon. 3. In all five post-treatment measurement campaigns, mean R at 25 degrees C was elevated in the TFR forest compared to the Control forest experiencing normal rainfall. After 5 years of the TFR treatment, R per unit leaf area and mass had increased by 65% and 42%, respectively, relative to pre-treatment means. In contrast, leaf area index (L) in the TFR forest was consistently lower than the Control, falling by 23% compared to the pre-treatment mean, largely because of a decline in specific leaf area (S). 4. The consistent and significant effects of the TFR treatment on R, L and S suggest that severe drought events in the Amazon, of the kind that may occur more frequently in future, could cause a substantial increase in canopy carbon dioxide emissions from this ecosystem to the atmosphere.

  • 9.
    Näsholm, Torgny
    et al.
    Swedish Univ Agr Sci SLU, Dept Forest Ecol & Management, SE-90183 Umea, Sweden.
    Högberg, Peter
    Swedish Univ Agr Sci SLU, Dept Forest Ecol & Management, SE-90183 Umeå, Sweden.
    Franklin, Oskar
    Int Inst Appl Syst Anal, A-2361 Laxenburg, Austria.
    Metcalfe, Daniel
    Swedish Univ Agr Sci SLU, Dept Forest Ecol & Management, SE-90183 Umeå, Sweden.
    Keel, Sonja G.
    Swedish Univ Agr Sci SLU, Dept Forest Ecol & Management, SE-90183 Umeå, Sweden.
    Campbell, Catherine
    SLU, Umeå Plant Sci Ctr, Dept Forest Genet & Plant Physiol, SE-90185 Umeå, Sweden.
    Hurry, Vaughan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Linder, Sune
    SLU, Southern Swedish Forest Res Ctr, SE-23053 Alnarp, Sweden.
    Högberg, Mona N.
    Swedish Univ Agr Sci SLU, Dept Forest Ecol & Management, SE-90183 Umeå, Sweden.
    Are ectomycorrhizal fungi alleviating or aggravating nitrogen limitation of tree growth in boreal forests?2013Inngår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 198, nr 1, s. 214-221Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Symbioses between plant roots and mycorrhizal fungi are thought to enhance plant uptake of nutrients through a favourable exchange for photosynthates. Ectomycorrhizal fungi are considered to play this vital role for trees in nitrogen (N)-limited boreal forests. We followed symbiotic carbon (C)N exchange in a large-scale boreal pine forest experiment by tracing 13CO2 absorbed through tree photosynthesis and 15N injected into a soil layer in which ectomycorrhizal fungi dominate the microbial community. We detected little 15N in tree canopies, but high levels in soil microbes and in mycorrhizal root tips, illustrating effective soil N immobilization, especially in late summer, when tree belowground C allocation was high. Additions of N fertilizer to the soil before labelling shifted the incorporation of 15N from soil microbes and root tips to tree foliage. These results were tested in a model for CN exchange between trees and mycorrhizal fungi, suggesting that ectomycorrhizal fungi transfer small fractions of absorbed N to trees under N-limited conditions, but larger fractions if more N is available. We suggest that greater allocation of C from trees to ectomycorrhizal fungi increases N retention in soil mycelium, driving boreal forests towards more severe N limitation at low N supply.

  • 10.
    Stangl, Zsofia R.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Campbell, Catherine D.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Näsholm, Torgny
    Hurry, Vaughan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Nitrogen limitation differentially affects acclimation by two contrasting Betula species to low and high growth temperatures and decreases the advantage of fast growth strategy under warming climatesManuskript (preprint) (Annet vitenskapelig)
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