Research Group PLECO (Plants and Ecosystems), Department of Biology, University of Antwerp, Campus Drie Eiken, Universiteitplan 1, 2160 Wilrijk, Belgium.
UMR 6553 ECOBIO (Ecosystèmes, Biodiversité, Evolution), Université de Rennes 1, CNRS, 263 Av. du Général Leclerc, 35042 Rennes, France.
Tree Physiol. 2021 Jul 5;41(7):1161-1170. doi: 10.1093/treephys/tpaa171.
We explored the timing of spring xylogenesis and its potential drivers in homogeneous mature forest stands in a temperate European region. Three species with contrasting leaf development dynamics and wood anatomy were studied: European beech, silver birch and pedunculate oak. Detailed phenological observations of xylogenesis and leaf phenology were performed from summer 2017 until spring 2018. Cambium reactivation (CR) occurred before the buds of oak and birch were swollen, whereas these two phenological phases were concurrent for beech. On the other hand, initial earlywood vessels were fully differentiated (FDIEV) after leaf unfolding for all three species. Timing of CR was correlated to average ring-width of the last 10 years (2008-17), tree diameter and, partially, with tree age. In addition, the timing of FDIEV was correlated to tree age and previous year's autumn phenology, i.e., timing of wood growth cessation and onset of leaf senescence. Multivariate models could explain up to 68% of the variability of CR and 55% of the variability of FDIEV. In addition to the 'species' factor, the variability could be explained by ca 30% by tree characteristics and previous year's autumn phenology for both CR and FDIEV. These findings are important to better identify which factors (other than environment) can be driving the onset of the growing season, and highlight the influence of tree growth characteristics and previous year's phenology on spring wood phenology, wood formation and, potentially, forest production.
我们探索了在温带欧洲地区同质成熟林分中春季木质部形成的时间及其潜在驱动因素。研究了三种具有不同叶片发育动态和木材解剖结构的物种：欧洲山毛榉、银桦和栓皮栎。从 2017 年夏季到 2018 年春季，我们对木质部形成和叶片物候进行了详细的物候观测。栎属和桦木的形成层活动（CR）发生在芽肿胀之前，而这两个物候阶段在山毛榉中是同时发生的。另一方面，对于所有三种树种，最初的早材导管完全分化（FDIEV）发生在叶片展开之后。CR 的时间与过去 10 年（2008-17 年）的平均年轮宽度、树径以及部分与树龄有关。此外，FDIEV 的时间与树龄和前一年的秋季物候有关，即木质部生长停止和叶片衰老开始的时间。多元模型可以解释 CR 变化的 68%和 FDIEV 变化的 55%。除了“物种”因素外，还可以用树木特征和前一年秋季物候来解释 CR 和 FDIEV 变化的 30%左右。这些发现对于更好地确定哪些因素（除了环境）可以驱动生长季节的开始非常重要，并强调了树木生长特征和前一年物候对春季木质部物候、木材形成以及潜在的森林生产力的影响。
