Key message

Near upper forest line, values of conifer wood anatomical traits are species-specific, but relationships among traits are common. Growing season temperature significantly impacts wood anatomy only in its extremes.

Abstract

Quantitative wood anatomy can provide detailed insight into adaptation of trees to changing environment, especially on the borders of species distribution ranges. This study investigated wood anatomy of Pinus sylvestris L., Pinus sibirica Du Tour, and Picea obovata Ledeb. near the forest line in the Western Sayan Mountains, where local climate changes rapidly. Anatomical traits reflecting three developmental stages of conifer tracheids (division = cell number, cell enlargement = radial diameter, and secondary wall deposition = cell wall thickness) were calculated for earlywood, latewood and total tree ring over 50 years. Similar earlywood anatomical structure and low between-trait correlations (r = 0.21…67) were observed in all species, which supports prevalence of external impact on its formation, i.e. that shared habitat, climate, and similar habitus provide common trade-off between hydraulic efficiency and safety. Also, stronger nonlinearity of relationship between cell number and radial diameter in earlywood decreased correlations between them. In latewood, anatomical traits are strongly interconnected (r = 0.63…93) for all species. However, Siberian pine has significantly less pronounced latewood; later switch from earlywood and different strategy of carbon allocation are proposed as possible reasons. Length of vegetative season and sum of temperatures above thresholds 5 °C and 8 °C have no significant correlations with anatomical traits, but extremes of these temperature variables led to forming more pronounced latewood (higher proportion of latewood cells with thicker walls) during warm/long vegetative seasons than during short/cool ones.

中文翻译：

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森林线附近的常绿针叶树的早木结构是栖息地驱动的，但晚木取决于物种和季节

关键信息

在上林线附近，针叶树木材解剖特征的值是特定于物种的，但是特征之间的关系是常见的。生长季节的温度仅在极端情况下才显着影响木材解剖结构。

抽象

定量的木材解剖学可以为树木适应不断变化的环境提供详细的见识，尤其是在物种分布范围的边界上。这项研究调查了樟子松，西伯利亚松树杜鹃和云杉云杉的木材解剖。靠近萨彦岭西部森林线，那里的当地气候变化迅速。计算了50年内早材，晚材和总年轮的解剖特征，这些特征反映了针叶气管的三个发育阶段（划分=细胞数量，细胞扩大=径向直径和次生壁沉积=细胞壁厚度）。相似的早木解剖结构和低性状间相关性（r = 0.21…67）在所有物种中均得到观察，这支持了对其形成的外部影响的普遍性，即共享的栖息地，气候和类似的习性在水力效率和安全性之间提供了共同的权衡。同样，早材中细胞数量与径向直径之间关系的更强非线性降低了它们之间的相关性。在晚木中，解剖学特征紧密相关（r = 0.63…93）。但是，西伯利亚松的晚材明显不足。后来从早材转变到碳分配的不同策略被认为是可能的原因。营养季节的长度和高于阈值5°C和8°C的温度总和与解剖学特征没有显着相关性，但是这些温度变量的极端值导致在温暖/高温期间形成更明显的晚材（较高比例的晚材细胞且壁较厚）。长的植物生长季节要比短/凉的季节长。