In the eastern Canadian boreal forest, long fire return intervals lead to over 60% of stands having an irregular, uneven-aged structure, which is associated with slower growth. The aim of this study was to evaluate the effect of stand structure on the dimensional stability of black spruce wood [Picea mariana (Mill.) B.S.P.]. Sixty trees were sampled from stands with regular and irregular structures from the North Shore region of Quebec, Canada. Nonlinear mixed-effect models were developed for each stand structure to describe the variation in two indicators of dimensional stability, the differential volumetric shrinkage ratio (G_V) and the dimensional hygroexpansion coefficient (R-ratio), in small defect-free wood samples as functions of cambial age and annual ring width. G_V and R-ratio were strongly related to cambial age, but there was a limited effect of ring width. After accounting for these variables, samples from stands of irregular structure had greater dimensional stability than those from stands with a regular structure, although G_V and R-ratio differences were more pronounced in the upper stem compared with breast height. The fixed effects of the models explained between 44 and 60% of the variation in G_V, and between 7 and 44% of the variation in R-ratio. A higher presence of mild reaction wood or lower within-ring variation in wood density in trees of layer origin from irregular stands may explain the observed differences between stand structures.

在加拿大东部北方森林，长时间的火灾重现间隔导致超过 60% 的林分具有不规则、不均匀的年龄结构，这与生长缓慢有关。本研究的目的是评估林分结构对黑云杉木材 [ Picea mariana (Mill.) BSP]尺寸稳定性的影响。从加拿大魁北克北岸地区具有规则和不规则结构的林分中取样了 60 棵树。为每个林分结构开发了非线性混合效应模型来描述尺寸稳定性的两个指标的变化，即差异体积收缩率 ( G _V ) 和尺寸湿膨胀系数 ( R-ratio)，在小的无缺陷木材样品中作为形成层年龄和年轮宽度的函数。G _V和R比与形成层年龄密切相关，但环宽的影响有限。考虑到这些变量后，来自不规则结构林分的样品比来自具有规则结构林分的样品具有更大的尺寸稳定性，尽管与胸高相比，上茎的G _V和R比差异更为明显。模型的固定效应解释了G _{V 中}44% 到60% 的变异，以及R 中7% 到 44% 的变异-比率。在来自不规则林分的层状树木中，轻度反应木材的存在较高或木材密度较低的环内变化可以解释林分结构之间观察到的差异。