Understanding how plant water uptake interacts with acquisition of soil nitrogen (N) and other nutrients is fundamental for predicting plant responses to a changing environment, but it is an area where models disagree. We present a novel isotopic labelling approach which reveals spatial patterns of water and N uptake, and their interaction, by trees. The stable isotopes 15 N and 2 H were applied to a small area of the forest floor in stands with high and low soil N availability. Uptake by surrounding trees was measured. The sensitivity of N acquisition to water uptake was quantified by statistical modelling. Trees in the high-N stand acquired twice as much 15 N as in the low-N stand and around half of their N uptake was dependent on water uptake (2 H enrichment). By contrast, in the low-N stand there was no positive effect of water uptake on N uptake. We conclude that tree N acquisition was only marginally dependent on water flux toward the root surface under low-N conditions whereas under high-N conditions, the water-associated N uptake was substantial. The results suggest a fundamental shift in N acquisition strategy under high-N conditions.

Department of Forest Ecology and Management Swedish University of Agricultural Sciences Umeå SE 90283 Sweden

Global Change Research Institute CAS Bělidla 986 4a Brno 603 00 Czech Republic

Institute of Forestry and Rural Engineering Estonian University of Life Sciences Kreutzwaldi 5 Tartu EE 510 06 Estonia

International Institute for Applied Systems Analysis Schlossplatz 1 Laxenburg A 2361 Austria

School of Biological Earth and Environmental Sciences The University of New South Wales Sydney NSW 2052 Australia

Zobrazit více v PubMed

Albaugh TJ. 1998. Leaf area and above- and belowground growth responses of loblolly pine to nutrient and water additions. Forest Science 44: 217-328.

Barber SA. 1995. Soil nutrient bioavailability - a mechanistic approach. New York, NY, USA: John Wiley & Sons.

Barber SA, Cushman JH. 1981. Nutrient uptake model for agronomic crops. In: Ilskander IK, ed. Modelling wastewater renovation land treatment. New York, NY, USA: John WIley & Sons, 382-409.

BassiriRad H, Gutchick V, Sehtiya H. 2008. Control of plant nitrogen uptake in native ecosystems by rhizopheric processes. In: Bruuslema T, Ma L, Ahuja L, eds. Quantifying and understanding plant nitrogen uptake for systems modeling. Boca Raton, FL, USA: CRC Press, 71-93.

Bishop DM. 1962. Lodgepole pine rooting habits in the blue mountains of northeastern Oregon. Ecology 43: 140-142.

Cheesman AW, Cernusak LA. 2017. Infidelity in the outback: climate signal recorded in Δ18O of leaf but not branch cellulose of eucalypts across an Australian aridity gradient. Tree Physiology 37: 554-564.

Cramer MD, Hoffmann V, Verboom GA. 2008. Nutrient availability moderates transpiration in Ehrharta calycina. New Phytologist 179: 1048-1057.

Ferrill MD, Woods FW. 1966. Root extension in a longleaf pine plantation. Ecology 47: 97-102.

Göttlicher SG, Taylor AFS, Grip H, Betson NR, Valinger E, Högberg MN, Högberg P. 2008. The lateral spread of tree root systems in boreal forests: estimates based on 15N uptake and distribution of sporocarps of ectomycorrhizal fungi. Forest Ecology and Management 255: 75-81.

Hasselquist NJ, Metcalfe DB, Inselsbacher E, Stangl Z, Oren R, Näsholm T, Högberg P. 2015. Greater carbon allocation to mycorrhizal fungi reduces tree nitrogen uptake in a boreal forest. Ecology 1012-1022.

Henriksson N, Franklin O, Tarvainen L, Marshall J, Lundberg-Felten J, Eilertsen L, Näsholm T. 2021. The mycorrhizal tragedy of the commons. Ecology Letters 24: 1215-1224.

Inselsbacher E, Näsholm T. 2012. The below-ground perspective of forest plants: soil provides mainly organic nitrogen for plants and mycorrhizal fungi. New Phytologist 195: 329-334.

Iversen CM, McCormack ML, Powell AS, Blackwood CB, Freschet GT, Kattge J, Roumet C, Stover DB, Soudzilovskaia NA, Valverde-Barrantes OJ et al. 2017. A global Fine-Root Ecology Database to address below-ground challenges in plant ecology. New Phytologist 215: 15-26.

Kalliokoski T, Makinen H, Jyske T, Nojd P, Linder S. 2013. Effects of nutrient optimization on intra-annual wood formation in Norway spruce. Tree Physiology 33: 1145-1155.

Kiba T, Krapp A. 2016. Plant nitrogen acquisition under low availability: regulation of uptake and root architecture. Plant and Cell Physiology 57: 707-714.

Kulmatiski A, Adler PB, Stark JM, Tredennick AT. 2017. Water and nitrogen uptake are better associated with resource availability than root biomass. Ecosphere 8: 1-10.

Lambers H, Chapin FS III, Pons T. 1998. Plant physiological ecology. New York, NY, USA: Springer.

Leadley PW, Reynolds JF, Chapin FS. 1997. A model of nitrogen uptake by Eriophorum vaginatum roots in the field: ecological implications. Ecological Monographs 67: 22.

Lehmann MM, Vitali V, Schuler P, Leuenberger M, Saurer M. 2021. More than climate: hydrogen isotope ratios in tree rings as novel plant physiological indicator for stress conditions. Dendrochronologia 65: 125788.

Lim H, Oren R, Palmroth S, Tor-ngern P, Mörling T, Näsholm T, Lundmark T, Helmisaari H-S, Leppälammi-Kujansuu J, Linder S. 2015. Inter-annual variability of precipitation constrains the production response of boreal Pinus sylvestris to nitrogen fertilization. Forest Ecology and Management 348: 31-45.

Makinen H, Hynynen J. 2014. Wood density and tracheid properties of Scots pine: responses to repeated fertilization and timing of the first commercial thinning. Forestry 87: 437-448.

Matimati I, Verboom GA, Cramer MD. 2014. Nitrogen regulation of transpiration controls mass-flow acquisition of nutrients. Journal of Experimental Botany 65: 159-168.

McCormack ML, Dickie IA, Eissenstat DM, Fahey TJ, Fernandez CW, Guo D, Helmisaari H-S, Hobbie EA, Iversen CM, Jackson RB et al. 2015. Redefining fine roots improves understanding of below-ground contributions to terrestrial biosphere processes. New Phytologist 207: 505-518.

McCormack ML, Guo D, Iversen CM, Chen W, Eissenstat DM, Fernandez CW, Li Le, Ma C, Ma Z, Poorter H et al. 2017. Building a better foundation: improving root-trait measurements to understand and model plant and ecosystem processes. New Phytologist 215: 27-37.

McMurtrie RE, Näsholm T. 2018. Quantifying the contribution of mass flow to nitrogen acquisition by an individual plant root. New Phytologist 218: 119-130.

Näsholm T, Högberg P, Franklin O, Metcalfe D, Keel SG, Campbell C, Hurry V, Linder S, Högberg MN. 2013. Are ectomycorrhizal fungi alleviating or aggravating nitrogen limitation of tree growth in boreal forests? New Phytologist 198: 214-221.

Nye PH, Marriott FHC. 1969. A theoretical study of the distribution of substances around roots resulting from simultaneous diffusion and mass flow. Plant and Soil 30: 459-472.

Oyewole OA, Inselsbacher E, Näsholm T. 2014. Direct estimation of mass flow and diffusion of nitrogen compounds in solution and soil. New Phytologist 201: 1056-1064.

Oyewole OA, Jämtgård S, Gruffman L, Inselsbacher E, Näsholm T. 2016. Soil diffusive fluxes constitute the bottleneck to tree nitrogen nutrition in a Scots pine forest. Plant and Soil 399: 109-120.

Roden JS, Ehleringer JR. 1999. Observations of hydrogen and oxygen isotopes in leaf water confirm the Craig-Gordon model under wide-ranging environmental conditions. Plant Physiology 120: 1165-1174.

Samuelson LJ, Farris MG, Stokes TA, Coleman MD. 2008. Fertilization but not irrigation influences hydraulic traits in plantation-grown loblolly pine. Forest Ecology and Management 255: 3331-3339.

Sternberg L da SL, Moreira MZ, Nepstad DC. 2002. Uptake of water by lateral roots of small trees in an Amazonian tropical forest. Plant and Soil 238: 151-158.

Taskinen O, Ilvesniemi H, Kuuluvainen T, Leinonen K. 2003. Response of fine roots to an experimental gap in a boreal Picea abies forest. Plant and Soil 255: 503-512.

Tinker PB, Nye PH. 2000. Solute movement in the rhizosphere. New York, NY, USA: Oxford University Press.

Wang G, Liu F, Xue S. 2017. Nitrogen addition enhanced water uptake by affecting fine root morphology and coarse root anatomy of Chinese pine seedlings. Plant and Soil 418: 177-189.

Williams M, Yanai RD. 1996. Multi-dimensional sensitivity analysis and ecological implications of a nutrient uptake model. Plant and Soil 180: 311-324.

Yanai RD. 1994. A steady-state model of nutrient uptake accounting for newly grown roots. Soil Science Society of America Journal 58: 1562-1571.

Zaehle S, Medlyn BE, De Kauwe MG, Walker AP, Dietze MC, Hickler T, Luo Y, Wang Y, El-Masri B, Thornton P et al. 2014. Evaluation of 11 terrestrial carbon-nitrogen cycle models against observations from two temperate Free-Air CO2 Enrichment studies. New Phytologist 202: 803-822.