Tree water uptake enhances nitrogen acquisition in a fertilized boreal forest - but not under nitrogen-poor conditions

Abstract

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 N-15 and H-2 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 N-15 as in the low-N stand and around half of their N uptake was dependent on water uptake (H-2 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.

Keywords

N-15; deuterium; diffusion; isotope; mass flow; nitrogen uptake; Pinus sylvestris (Scots pine); water uptake

Published in

New Phytologist
2021, volume: 232, number: 1, pages: 113-122
Publisher: WILEY

SLU Authors

• Henriksson, Nils

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Lim, Hyungwoo

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Marshall, John

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    
  • The Czech Academy of Sciences

• Franklin, Oskar

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    
  • International Institute for Applied Systems Analysis (IIASA)

• Lutter, Reimo

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    
  • Estonian University of Life Sciences

• Magh, Ruth

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Lundmark, Tomas

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Näsholm, Torgny

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Forest Science

Publication identifier

• DOI: https://doi.org/10.1111/nph.17578

Permanent link to this page (URI)

https://res.slu.se/id/publ/113224