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- Title
Winter at the alpine timberline causes complex within-tree patterns of water potential and embolism in Picea abies.
- Authors
Mayr, Stefan; Charra-Vaskou, Katline
- Abstract
Winter temperatures at the alpine timberline cause ice formation in the xylem of conifers blocking water uptake as well as water shifts within the axes system. This amplifies drought stress that, in combination with freeze–thaw events, causes embolism. This study focussed on within-tree patterns of water potential (ψ) and embolism in Norway spruce [ Picea abies (L.) Karst.]. At five sampling dates in midwinter, ψ was determined at numerous positions in the crown of three trees, and at the end of March, the extent of embolism in representative sections of the axes system was analysed. Until 14 March, mean ψ decreased to −3.77 ± 0.11 MPa with less negative ψ in exposed crown parts. On 30 March, ψ was −1.60 ± 0.06 MPa, while loss of conductivity reached up to 100%. Conductivity losses increased with exposition and were highest in the smallest tree. The observed complex within-tree patterns of ψ and embolism were caused by ice blockages and differences in stress intensities within the xylem. High conductivity losses despite moderate ψ in exposed crown parts indicated freeze–thaw events to be a major inducer of winter embolism. Tree size may play a critical role for winter water relations as trees profit from water stored in the stem and in crown parts below the snow cover.
- Subjects
BOTANICAL research; PLANTS in winter; MOUNTAIN ecology; TIMBERLINE; XYLEM; NORWAY spruce; CONIFERS; PLANT physiology; PLANT cells &; tissues; EMBOLISMS
- Publication
Physiologia Plantarum, 2007, Vol 131, Issue 1, p131
- ISSN
0031-9317
- Publication type
Article
- DOI
10.1111/j.1399-3054.2007.00942.x