Badel Eric, Ewers Frank W, Cochard Hervé, Telewski Frank W
INRA, UMR 547 PIAF, Clermont-Ferrand France ; Clermont Université-Université Blaise-Pascal, UMR 547 PIAF, Clermont-Ferrand France.
Department of Biological Sciences, California State Polytechnic University Pomona, CA, USA.
Front Plant Sci. 2015 Apr 22;6:266. doi: 10.3389/fpls.2015.00266. eCollection 2015.
The secondary xylem (wood) of trees mediates several functions including water transport and storage, mechanical support and storage of photosynthates. The optimal structures for each of these functions will most likely differ. The complex structure and function of xylem could lead to trade-offs between conductive efficiency, resistance to embolism, and mechanical strength needed to count for mechanical loading due to gravity and wind. This has been referred to as the trade-off triangle, with the different optimal solutions to the structure/function problems depending on the environmental constraints as well as taxonomic histories. Thus, the optimisation of each function will lead to drastically different anatomical structures. Trees are able to acclimate the internal structure of their trunk and branches according to the stress they experience. These acclimations lead to specific structures that favor the efficiency or the safety of one function but can be antagonistic with other functions. Currently, there are no means to predict the way a tree will acclimate or optimize its internal structure in support of its various functions under differing environmental conditions. In this review, we will focus on the acclimation of xylem anatomy and its resulting mechanical and hydraulic functions to recurrent mechanical strain that usually result from wind-induced thigmomorphogenesis with a special focus on the construction cost and the possible trade-off between wood functions.
树木的次生木质部（木材）具有多种功能，包括水分运输与储存、机械支撑以及光合产物的储存。这些功能各自的最优结构很可能有所不同。木质部复杂的结构与功能可能导致在传导效率、抗栓塞能力以及应对重力和风引起的机械负荷所需的机械强度之间进行权衡。这被称为权衡三角，针对结构/功能问题的不同最优解决方案取决于环境限制以及分类学历史。因此，每种功能的优化都会导致截然不同的解剖结构。树木能够根据其所经历的应力来适应其树干和树枝的内部结构。这些适应性变化会导致形成特定的结构，这些结构有利于某一功能的效率或安全性，但可能与其他功能相互拮抗。目前，尚无办法预测树木在不同环境条件下将如何适应或优化其内部结构以支持其各种功能。在本综述中，我们将重点关注木质部解剖结构的适应性变化及其产生的机械和水力功能，以应对通常由风致形态建成引起的反复机械应变，并特别关注建设成本以及木材功能之间可能存在的权衡。
