Injury to the xylem and vascular cambium is proposed to explain mortality following low severity fires. These tissues have been assessed independently, but the relative significance of the xylem and cambium is still uncertain. The goal of this study is to evaluate the xylem dysfunction hypothesis and cambium necrosis hypothesis simultaneously. The hot dry conditions of a low severity fire were simulated in a drying oven, exposing Sequoia sempervirens (Lamb. ex D. Don) shoots to 70 and 100 °C for 6–60 min. Cambial viability was measured with Neutral Red stain and water transport capacity was assessed by calculating the loss of hydraulic conductivity. Vulnerability curves were also constructed to determine susceptibility to drought-induced embolism following heat exposure. The vascular cambium died completely at 100 °C after only 6 min of heat exposure, while cells remained viable at 70 °C temperatures for up to 15 min. Sixty minutes of exposure to 70 °C reduced stem hydraulic conductivity by 40%, while 45 min at 100 °C caused complete loss of conductivity. The heat treatments dropped hydraulic conductivity irrecoverably but did not significantly impact post-fire vulnerability to embolism. Overall, the damaging effects of high temperature occurred more rapidly in the vascular cambium than xylem following heat exposure. Importantly, the xylem remained functional until the most extreme treatments, long after the vascular cambium had died. Our results suggest that the viability of the vascular cambium may be more critical to post-fire survival than xylem function in S. sempervirens. Given the complexity of fire, we recommend ground-truthing the cambial and xylem post-fire response on a diverse range of species.
Fire scars on trees are created by excessive heat from a fire that kills the vascular cambium. Although, fires are one of the most important forest disturbances in Patagonia, the effects of fire on tree physiology and wood anatomy are still unknown. In this study, we hypothesized that abnormal functioning of the cambium after a fire will induce anatomical changes in the wood. We also assumed that these anatomical changes would affect xylem safety transport.
We quantified wood anatomical traits in
Reductions in lumen diameter and vessel number were the most conspicuous changes associated with fire damage and observed in the fire ring and subsequent post‐fire rings. In addition, the fire ring had more rays than in control rings. In terms of distance, anatomical changes were only restricted to short distances from the wound.
Post‐fire changes in wood anatomical traits were confined close to the wound margins. These changes might be associated with a defense strategy related to the compartmentalization of the wound and safety of water transport.
- Award ID(s):
- 1832483
- NSF-PAR ID:
- 10459235
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- American Journal of Botany
- Volume:
- 106
- Issue:
- 12
- ISSN:
- 0002-9122
- Page Range / eLocation ID:
- p. 1536-1544
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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