Drought-induced adaptation of the xylem in Scots pine and pubescent oak
Drought-induced adaptation of the xylem in Scots pine and pubescent oak
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DOI：
10.1093/treephys/tpp035
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发表时间：
2009-08-01
期刊：
影响因子：
4
通讯作者：
Rigling, Andreas
中科院分区：
文献类型：
--
作者：
Eilmann, Britta;Zweifel, Roman;Rigling, Andreas
干旱损害了中欧内阿尔卑斯山山谷的树木生长。我们研究了不同物种对不同供水的反应，其中樟子松受到干旱导致的死亡的威胁，而青春期的橡树(Quercus pubescens Wild.)则没有发现干旱事件和死亡之间的联系。对这两种共存的树种进行了比较，它们要么生长在开阔的水道上，要么生长在自然干燥的地方。此外，还研究了樟子松对排水渠道的生长响应。我们分析了近100年的径向生长量和近45年的木材解剖参数。干旱使樟子松青春期导管面积减小，径向管腔直径增大。干旱条件下，两种树种的径向生长量均有所降低。在樟子松中，径向生长量通常比在青春期的橡树中更依赖于水分的有效性。浇灌的树木对高温的负面反应较少，表现在青春期橡树导管面积的增加和高温对细胞分裂的限制。停止灌溉后，樟子松的年轮宽度在1年内减小，而管腔直径和细胞壁厚度则延迟4年。在干旱条件下，樟子松似乎通过增加导管直径和减少细胞数量来优化每根导管的碳成本。这一战略可能导致在严重干旱情况下树木年轮的完全丧失，从而损害水分运输。相比之下，青春期的橡树年轮宽度受夏季干旱的影响较小，因为部分早熟橡树是在早春建成的。因此，在今天内阿尔卑斯山山谷的气候中，青春期的橡木可能比松木有逐渐的优势。
Drought impairs tree growth in the inner-Alpine valleys of Central Europe. We investigated species-specific responses to contrasting water supply, with Scots pine (Pinus sylvestris L.), threatened by drought-induced mortality, and pubescent oak (Quercus pubescens Willd.), showing no connection between drought events and mortality. The two co-occurring tree species were compared, growing either along an open water channel or at a site with naturally dry conditions. In addition, the growth response of Scots pine to a draining of a water channel was studied. We analysed the radial increment for the last 100 years and wood anatomical parameters for the last 45 years. Drought reduced the conduit area of pubescent oak, but increased the radial lumen diameter of the conduits in Scots pine. Both species decreased their radial increment under drought. In Scots pine, radial increment was generally more dependent on water availability than that in pubescent oak. Irrigated trees responded less negatively to high temperature as seen in the increase in the conduit area in pubescent oak and the removal of the limitation of cell division by high temperatures. After irrigation stopped, tree-ring width for Scots pine decreased within 1-year delay, whereas lumen diameter and cell-wall thickness responded with a 4-year delay. Scots pine seemed to optimize the carbon-per-conduit-costs under drought by increasing conduits diameter while decreasing cell numbers. This strategy might lead to a complete loss of tree rings under severe drought and thus to an impairment of water transport. In contrast, in pubescent oak tree-ring width is less affected by summer drought because parts of the earlywood are built in early spring. Thus, pubescent oak might have gradual advantages over pine in today's climate of the inner-Alpine valley.