4.7 Article

How do drought and warming influence survival and wood traits of Picea mariana saplings?

期刊

JOURNAL OF EXPERIMENTAL BOTANY
卷 66, 期 1, 页码 377-389

出版社

OXFORD UNIV PRESS
DOI: 10.1093/jxb/eru431

关键词

Carbon balance; climate change; drought; survival; warming; wood anatomy; wood density

资金

  1. Natural Sciences and Engineering Research Council of Canada
  2. Consortium Ouranos

向作者/读者索取更多资源

Warming and drought will occur with increased frequency and intensity at high latitudes in the future. How heat and water stress can influence tree mortality is incompletely understood. The aim of this study was to evaluate how carbon resources, stem hydraulics, and wood anatomy and density determine the ability of black spruce saplings to survive daytime or night-time warming (+ 6 degrees C in comparison with control) in combination with a drought period. Plant water relations, the dynamics of non-structural carbohydrates and starch, mortality rate, and wood anatomy and density of saplings were monitored. Warming, in conjunction with 25 d of water deficit, increased sapling mortality (10% and 20% in night-time and daytime warming, respectively) compared with the control conditions (0.8%). Drought substantially decreased gas exchange, and also pre-dawn and mid-day leaf water potential to values close to -3 MPa which probably induced xylem embolism (xylem air entry point, P-12, being on average around -3 MPa for this species). In addition, the recovery of gas exchange never reached the initial pre-stress levels, suggesting a possible loss of xylem hydraulic conductivity associated with cavitation. Consequently, mortality may be due to xylem hydraulic failure. Warmer temperatures limited the replenishment of starch reserves after their seasonal minimum. Lighter wood was formed during the drought period, reflecting a lower carbon allocation to cell wall formation, preventing the adaptation of the hydraulic system to drought. Saplings of black spruce experienced difficulty in adapting under climate change conditions, which might compromise their survival in the future.

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