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

Henriksson, N., Lim, H., Marshall, J., Franklin, O. ORCID: https://orcid.org/0000-0002-0376-4140, McMurtrie, R.E., Lutter, R., Magh, R., Lundmark, T., et al. (2021). Tree water uptake enhances nitrogen acquisition in a fertilized boreal forest – but not under nitrogen poor conditions. New Phytologist 10.1111/nph.17578. (In Press)

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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 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). In 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 but 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.

Item Type: Article
Uncontrolled Keywords: 15N; Pinus sylvestris (Scots pine); deuterium; diffusion; isotope; mass flow; nitrogen uptake; water uptake
Research Programs: Biodiversity and Natural Resources (BNR)
Biodiversity and Natural Resources (BNR) > Agriculture, Forestry, and Ecosystem Services (AFE)
Depositing User: Luke Kirwan
Date Deposited: 05 Jul 2021 09:11
Last Modified: 27 Aug 2021 17:34
URI: http://pure.iiasa.ac.at/17294

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