Regeneration and precommercial thinning silviculture of boreal mixed stands

白杨/云杉混交林的收获往往会导致种植的或预先建立的针叶树苗很快被茂密而有力的杨树吸盘覆盖。然后，需要做出重大的营林努力，以释放针叶树部分，并保持这些林分的混合结构。这项研究的第一个目标是评估云杉和杨树对两种常用的商业前间伐处理(系统间伐或作物-树木释放)的响应，从这两个物种的树木和林分生产力、动物栖息地质量以及土壤和地上、地下植被中固碳的动态。其次，我们想要评估杨树的公共根系在混合林中对商业前间伐和保留收获的反应中所起的作用。事实上，以前的研究已经表明，杨树相互关联的根系在树木对环境变化的生理反应中发挥了作用，我们希望利用这一知识来设计适应混交林背景下的营林情景。商业前间伐选择只保留最大的树干，无论它们的空间分布如何，都应该产生更有活力的更大的个体树干，以及随机分布的开口，用云杉幼苗丰富。此外，保留采伐选择，通过保持顶端优势进入共同的根系，保持穿插的杨树茎，应该会减少收获后产生的杨树吸盘的数量，为云杉苗木提供更好的生长条件，未来需要较少的营林干预。这项研究的结果将很容易地被转移到林业行业和MFFP(MFFP)的管理者，提供缺失的信息，根据管理目标指导森林培育选择，无论这些目标主要侧重于针叶或阔叶林生产力，或两者兼而有之，或固碳或最大限度地维持高质量的野生动物栖息地，或以上两者的组合。因此，我们将利用这项研究的结果，为北方针叶林的白杨/云杉混交林推荐合适的经营措施。

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.