4.7 Article

In situ embolism induction reveals vessel refilling in a natural aspen stand

期刊

TREE PHYSIOLOGY
卷 38, 期 7, 页码 1006-1015

出版社

OXFORD UNIV PRESS
DOI: 10.1093/treephys/tpy007

关键词

aspen; bubble dissolusion; embolism; hydraulic stress; xylem refilling

类别

资金

  1. University of Utah
  2. [NSF-IOS-1450650]
  3. Division Of Integrative Organismal Systems
  4. Direct For Biological Sciences [1450650] Funding Source: National Science Foundation

向作者/读者索取更多资源

Little is known about the ability of trees to recover hydraulic conductance (k) within a growing season by regrowth or refilling of embolized conduits. Recovery of k lost to drought or other causes would prevent chronic reductions in gas exchange and productivity. To test recovery ability we conducted a 2-year experiment (2014-15) on a cohort of aspen ramets (Populus tremuloides, Michx.). Whole-tree k was measured from mid-June through September from sapflow (Q) and pre-dawn and mid-day xylem pressure. We induced embolism in the treatment group with high air pressure delivered by a split pressure chamber sealed around the main trunk. Successful treatments reduced k and Q by 50% or more without causing rapid desiccation. The majority of trees recovered following treatment, rising to control levels of k and Q between 12 and 17 days. Failure to recover was correlated with drier climate conditions. The growing-season recovery of k was attributed to refilling of embolized vessels, based on the absence of diameter growth. Pre-dawn xylem pressures during recovery were similar to the threshold needed to passively collapse emboli. Successful recovery during the 2-year study was consistent with no reduction in cumulative Q or canopy area in treatment vs controls. However, non-recovering trees in 2014 exhibited lower basal area growth at the start of the 2015 growing season, suggesting a linkage between recovery ability and productivity. This study provides evidence for the potential of trees to recover xylem function by refilling during the growing season.

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