ABSTRACT

To better understand the long-term response of boreal forests to increasing environmental changes, we applied the u-w method to detect growth changes triggered by environmental factors. Three species (Picea mariana, Picea glauca, and Populus tremuloides) of various sizes and ages were sampled in a boreal forest in northern Canada. Several stem disks were collected from the base to the crown of seven or eight trees in each of ten plots and ring width was measured to estimate the annual volume growth of each tree. Growth shifts, or changes in the phase of volume growth, were observed in every tree, and some shift years were common to the plots and species, suggesting the same environmental impact on trees. More frequent growth shifts were observed in the smallest trees in the black spruce plots, but showed no common patterns among the trees of different ages/sizes and species. Common growth shifts across species and plots were observed after severe drought years associated with fire incidences. We concluded that the u-w method is useful for detecting multi-year climate impacts on tree growth.

摘要

为了更好地了解北方森林对环境变化加剧的长期响应，我们采用了uw方法来检测环境因素触发的生长变化。三种树种（云杉云杉，云杉云杉和胡杨））的大小和年龄各不相同）是从加拿大北部的一个北方森林中取样的。在十个样地中的每棵中，从七到八棵树的根部到树冠收集了数个茎盘，并测量了环的宽度以估计每棵树的年体积增长。在每棵树上都观察到了生长变化或体积生长阶段的变化，并且这些变化的年份对于地块和物种来说是共同的，这表明对树木的环境影响也是相同的。在黑云杉地块的最小树木中观察到更频繁的生长变化，但在不同年龄/大小和物种的树木之间没有显示出共同的模式。在与火灾发生相关的严重干旱年份之后，观察到物种和地块的共同生长变化。我们得出的结论是，uw方法可用于检测多年气候对树木生长的影响。