Over the last three decades, the ecological basis for the generalized use of even-aged silviculture in boreal forests has been increasingly challenged. In boreal mixed-wood landscapes, the diminishing proportion of conifers, to the benefit of intolerant hardwoods, has been a primary concern, coupled with the general rarefication of old-growth conifer-dominated stands. In this context, partial cutting, extended rotations and forest renewal techniques that eliminate or reduce regenerating hardwoods have been proposed as means of regaining greater conifer cover. As a result, experimentation and industrial application of various forms of both variable retention and partial harvesting are occurring across the commercial Canadian boreal forest. In this study, we compared the effects of two harvesting intensities, clearcutting and low-intensity partial cutting (removal of 25–31% of tree basal area), on hardwood and conifer regeneration levels 7–19 years following treatments in aspen (Populus tremuloides)-dominated stands and verified whether regeneration differences existed between micro-sites on and off machinery trails. The abundance of aspen regeneration increased with percent basal area removal and was positively correlated to the abundance of mature aspen prior to harvesting. The abundance of fir (Abies balsamea) regeneration after partial cutting was similar to controls and higher than after clear-cutting and was positively correlated with ground cover of mixed litter (i.e., mixture of needles and leaves) and negatively correlated with ground cover of broadleaf litter. These results suggest that it is possible in boreal mixed-woods to control aspen abundance and promote or maintain conifer regeneration through silvicultural treatments that limit canopy opening and promote mixed forest floor litter.

中文翻译：

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加拿大东部成熟的Aspen-Jack松林部分和清晰采伐后的自然更新

在过去的三十年中，在北方森林中普遍使用平均年龄的造林的生态基础受到了越来越多的挑战。在北方混交林景观中，针叶树比例不断下降（对不耐寒的硬木有利）已成为人们关注的主要问题，而以针叶树为主的老龄林普遍稀少。在这种情况下，已经提出了消除或减少再生硬木的部分伐木，延长轮伐和更新森林的技术，作为重新获得更大针叶树覆盖率的手段。结果，在整个加拿大寒带森林中，进行了各种形式的可变保留和部分采伐的试验和工业应用。在这项研究中，我们比较了两种收获强度的影响，以杨树（Populus tremuloides）为主的林分，并验证了机械轨迹上和下的微点之间是否存在再生差异。白杨再生的丰度随着基部面积去除率的增加而增加，并且与收获前成熟白杨的丰度成正相关。冷杉的丰富（冷杉冷杉）部分切割后的再生与对照相似，并且比透明切割后更高，并且与混合凋落物（即针叶的混合物）的地被覆盖呈正相关，与阔叶凋落物的地被覆盖呈负相关。这些结果表明，在北方混交林中，可以通过限制冠层开放并促进混交林地凋落物的造林处理，控制白杨的丰度并促进或维持针叶树的再生。