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Title: Carbon starvation following a decade of experimental drought consumes old reserves in Pinus edulis

Shifts in the age or turnover time of non‐structural carbohydrates (NSC) may underlie changes in tree growth under long‐term increases in drought stress associated with climate change. But NSC responses to drought are challenging to quantify, due in part to large NSC stores in trees and subsequently long response times of NSC to climate variation.

We measured NSC age (Δ14C) along with a suite of ecophysiological metrics inPinus edulistrees experiencing either extreme short‐term drought (−90% ambient precipitation plot, 2020–2021) or a decade of severe drought (−45% plot, 2010–2021). We tested the hypothesis that carbon starvation – consumption exceeding synthesis and storage – increases the age of sapwood NSC.

One year of extreme drought had no impact on NSC pool size or age, despite significant reductions in predawn water potential, photosynthetic rates/capacity, and twig and needle growth. By contrast, long‐term drought halved the age of the sapwood NSC pool, coupled with reductions in sapwood starch concentrations (−75%), basal area increment (−39%), and bole respiration rates (−28%).

Our results suggest carbon starvation takes time, as tree carbon reserves appear resilient to extreme disturbance in the short term. However, after a decade of drought, trees apparently consumed old stored NSC to support metabolism.

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Award ID(s):
1936205 1919506 1755362 2129747 2139080 1655499
Author(s) / Creator(s):
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Publisher / Repository:
Date Published:
Journal Name:
New Phytologist
Medium: X
Sponsoring Org:
National Science Foundation
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