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Forskningsartikel2021Vetenskapligt granskadÖppen tillgång

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

Henriksson, Nils; Lim, Hyungwoo; Marshall, John; Franklin, Oskar; McMurtrie, Ross E.; Lutter, Reimo; Magh, Ruth; Lundmark, Tomas; Nasholm, Torgny

Sammanfattning

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.

Nyckelord

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

Publicerad i

New Phytologist
2021, Volym: 232, nummer: 1, sidor: 113-122 Utgivare: WILEY