Winter at the alpine timberline causes complex within-tree patterns of water potential and embolism in Picea abies.
Winter at the alpine timberline causes complex within-tree patterns of water potential and embolism in Picea abies.
复制标题
高山林线的冬季会导致云杉树内复杂的水势和栓塞模式。
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
Katline Charra
中科院分区：
文献类型：
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作者：
S. Mayr;Katline Charra
冬季温度在高山林带线导致针叶树木质部结冰，阻碍水分吸收以及轴系统内的水分转移。这放大了干旱胁迫，再加上冻融事件，导致栓塞。研究了挪威云杉（Picea abies（L.）喀斯特）。在5个采样日期在隆冬，psi确定在许多位置在树冠上的三棵树，并在3月底，栓塞的程度在轴系统的代表性部分进行了分析。直到3月14日，平均psi下降到-3.77 +/- 0.11 MPa，暴露的冠部的负psi较小。3月30日，psi为-1.60 +/- 0.06 MPa，而电导率损失高达100%。电导率损失增加，曝光，最高的最小的树。所观察到的复杂的树内模式的psi和栓塞是由冰堵塞和木质部内的应力强度的差异。高电导率损失，尽管适度的psi在暴露的冠部分表示冻融事件是冬季栓塞的主要诱因。树的大小可能发挥关键作用，冬季水分关系，树木的利润从干和树冠部分以下的积雪储存的水。
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 (psi) and embolism in Norway spruce [Picea abies (L.) Karst.]. At five sampling dates in midwinter, psi 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 psi decreased to -3.77 +/- 0.11 MPa with less negative psi in exposed crown parts. On 30 March, psi 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 psi and embolism were caused by ice blockages and differences in stress intensities within the xylem. High conductivity losses despite moderate psi 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.