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首页> 外文期刊>Journal of Experimental Botany >A broad survey of hydraulic and mechanical safety in the xylem of conifers
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A broad survey of hydraulic and mechanical safety in the xylem of conifers

机译：针叶树木质部水力和机械安全的广泛调查

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Drought-induced forest dieback has been widely reported over the last decades, and the evidence for a direct causal link between survival and hydraulic failure (xylem cavitation) is now well known. Because vulnerability to cavitation is intimately linked to the anatomy of the xylem, the main objective of this study was to better understand the xylem anatomical properties associated with cavitation resistance. An extensive data set of cavitation resistance traits and xylem anatomical properties was developed for 115 conifer species, with special attention given to the micro-morphology of bordered pits. The ratio of torus to pit aperture diameter, so-called torus overlap, increased with increasing cavitation resistance, while the flexibility of the margo does not seem to play a role, suggesting that air-seeding is located at the seal between the aspirated torus and pit aperture. Moreover, punctured tori were reported in various Pinaceae species. Species resistant to cavitation had thicker tracheid walls, while their lumen diameter (conduit size) was only slightly reduced, minimizing the impact on hydraulic conductance. The results also demonstrated (i) the existence of an indirect trade-off between hydraulic safety and mechanical strength; and (ii) a consistency between species distribution and xylem anatomy: species with a wide torus overlap and high valve effects are found in arid environments such as the Mediterranean region.
机译：在过去的几十年中，已经广泛报道了干旱引起的森林枯死，并且众所周知，生存与水力衰竭（木质部空化）之间存在直接因果关系的证据。由于空化的脆弱性与木质部的解剖结构密切相关，因此本研究的主要目的是更好地了解与抗空化性相关的木质部的解剖特性。针对115个针叶树种开发了广泛的抗气蚀性状和木质部解剖学特性的数据集，并特别注意了有缘凹坑的微观形态。环面与坑口直径的比值，即所谓的环面重叠，随着抗气蚀性的增加而增加，而margo的柔韧性似乎并不起作用，这表明在播种的环面和吸气的环面之间的密封处存在气穴坑孔。此外，在松科的各种物种中都有刺破的花托的报道。耐气蚀性的物种的气管壁较厚，而其管腔直径（导管尺寸）仅略有减小，从而将对水力传导的影响降至最低。结果还表明：（i）在液压安全性和机械强度之间存在间接权衡; （ii）物种分布与木质部解剖结构之间的一致性：在干旱地区（例如地中海地区）发现具有宽环面重叠和高瓣效应的物种。

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