Regeneration and precommercial thinning silviculture of boreal mixed stands

收获的混合白杨/云杉林往往导致种植或预先建立的针叶树幼苗迅速被密集的有力的白杨吸盘。然后，需要进行重大的造林工作，以释放针叶树部分，并保持这些林分的混合结构。本研究的第一个目标是评估云杉生长密切的白杨两个常用的商业前间伐处理（系统或作物树释放）的树木和林分生产力方面的反应，两个物种，动物栖息地的质量和土壤和地上和地下植被的碳固存动态。第二，我们要评估的作用，白杨的公共根系的反应，在混合林前间伐和保留收获。事实上，以前的研究表明，相互连接的根系的白杨树发挥作用，在树木的生理反应，环境变化，我们希望利用这一知识，以设计适应造林方案在混交林的背景下。选择专门保留最大的茎，不管它们的空间分布，商业前间伐应产生更有力的更大的个体茎，以及随机分布的开口，以丰富云杉幼苗的立场。此外，保留收获选择保持穿插白杨茎，保持顶端优势进入公共根系，应减少收获后产生的白杨吸盘的数量，提供更好的生长条件，云杉幼苗需要较少的未来造林干预。这项研究的结果将很容易地转移到林业和森林、动物和公园部（MFFP）的管理人员，根据管理目标提供指导造林选择的缺失信息，无论他们主要关注针叶树或硬木生产力或两者兼而有之，还是碳固存或维持最高质量的野生动物栖息地，或这些的混合。因此，我们将使用本研究的结果，建议适当的管理措施，混合白杨/云杉林的北方森林。

Harvested mixed aspen/spruce stands often result in planted or pre-established conifer seedlings quickly being overtopped by dense vigorous aspen suckers. Significant silvicultural efforts are then required to release the conifer portion and maintain the mixed structure of these stands. The first goal of this study is to assess the response of spruce growing intimately with aspen to two frequently used precommercial thinning treatments (systematic or crop-tree release) in terms of tree and stand productivity for both species, fauna habitat quality and dynamics of carbon sequestration in soils and above- and belowground vegetation. Second, we want to evaluate the role of aspen's communal root system in the response to precommercial thinning and retention harvesting in mixed stands. Indeed, previous research has shown that interconnected root systems of aspen trees play a role in trees' physiological response to environmental changes, and we want to use this knowledge in order to design adapted silvicultural scenarios in a mixedwood forest context. Precommercial thinning choosing to exclusively keep the largest stems, regardless of their spatial distribution, should produce stands with more vigorous larger individual stems, as well as randomly distributed openings to be enriched with spruce seedlings. Also, retention harvesting selecting to keep interspersed aspen stems, by maintaining apical dominance into the communal root system, should reduce the number of aspen suckers produced post-harvest, offering better growing conditions for spruce seedlings requiring less future silvicultural intervention. Results of this research will be easily transferred to forest industry and managers of the Ministère des forêts, de la faune et des Parcs (MFFP), by offering missing information guiding silvicultural choices according to management objectives, whether they mostly focus on conifer or hardwood productivity or both, or on carbon sequestration or the maintenance of a maximum of quality wildlife habitats, or a mix of these. Accordingly we will use results of this research to recommend appropriate management practices for mixed aspen/spruce stands of the boreal forest.