Linking forest structure to forest productivity using remote sensing

利用遥感将森林结构与森林生产力联系起来

• 批准号: RGPIN-2021-02802
• 负责人: Schneider, Robert
• 金额: $ 2.62万
• 依托单位: Université du Québec à Rimouski
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=745106
• 关键词: Linking; forest; structure; productivity; using

Forest productivity, or how forests grow, is influenced by how the trees, their branches, and their leaves are positioned within the canopy. This complexity is, in turn, determined by both the species found in the forest and the architecture of individual trees. Past studies have reported that forests with a greater diversity of tree species have higher productivity; for example, higher-diversity forests can have less-spaced trees, leading to more trees in a given area. However, trees in mixed stands will occupy the canopy differently than if found within a monospecific stand. The relative effect of diversity versus structure on forest productivity remains nevertheless difficult to untangle. The question thus arises: Should forest managers aim for complexity or diversity to increase stand productivity? Advances in remote sensing, such as terrestrial and airborne LiDAR, have enabled researchers and forest managers to gain valuable insight into the detailed structure of forest canopies. The general objective of this research program is to improve forest management practices by describing forest structure and understanding its relationship to forest productivity. To achieve this long-term goal, the proposed research program will be divided into three themes: (I) develop easy-to-use indices to quantify stand structure for forest management. These remote sensing-derived indices quantify the 3D arrangement of woody and leaf material within a stand; (II) understand how forest structure influences forest productivity; and (III) synthesize this acquired information within a modelling framework to derive new forest management tools. The effect of forest structure on productivity will be studied within both an ecophysiological and biomechanical framework. Trees growing under different environmental and structural conditions differ in their growth. In terms of ecophysiology, climatic variables are hypothesized to influence how water flows within a tree and how growth shifts among the various tree compartments. In regard to biomechanics, trees subjected to strong winds will favour secondary growth (e.g. diameter growth at the base of the tree) to prevent buckling under mechanical constraints. The way wind interacts with forests is thus linked to canopy structure, through fluid dynamics at the canopy-atmosphere junction, and canopy porousness, by which wind enters the forest. The results will help better understand how forest diversity and structural complexity interact and influence forest productivity. For the forest industry to continue or increase its critical contribution to Canada's economy, forest management must adapt to new realities, such as ecosystem-based management and global change. Natural and anthropogenic disturbances will continue to increase pressure on Canada's forests. An improved understanding of stand structure and growth permits an evaluation of how best to structure forests to ensure they are resilient to projected pressures.

森林生产力，或者说森林的生长方式，受到树木、树枝和叶子在树冠内的位置的影响。这种复杂性反过来又取决于森林中发现的物种和个体树木的结构。过去的研究表明，树种多样性较高的森林生产力较高；例如，多样性较高的森林树木间距较小，从而导致特定区域内树木较多。然而，混合林分中的树木所占据的树冠结构与单一林分中的树木不同。然而，多样性与结构对森林生产力的相对影响仍然难以理清。因此，问题出现了：森林管理者是否应该以复杂性或多样性为目标来提高林分生产力？地面和机载激光雷达等遥感技术的进步使研究人员和森林管理者能够深入了解森林冠层的详细结构。该研究计划的总体目标是通过描述森林结构并了解其与森林生产力的关系来改进森林管理实践。为了实现这一长期目标，拟议的研究计划将分为三个主题：（I）开发易于使用的指数来量化森林管理的林分结构。这些源自遥感的指数量化了林分内木质和树叶材料的 3D 排列； （II）了解森林结构如何影响森林生产力； (III) 在建模框架内综合所获得的信息，以得出新的森林管理工具。将在生态生理学和生物力学框架内研究森林结构对生产力的影响。在不同的环境和结构条件下生长的树木，其生长情况有所不同。在生态生理学方面，假设气候变量会影响水在树内的流动方式以及不同树室之间的生长变化。就生物力学而言，遭受强风的树木将有利于二次生长（例如树根部的直径增长），以防止在机械约束下弯曲。因此，风与森林相互作用的方式与树冠结构（通过树冠-大气交界处的流体动力学）以及树冠多孔性（风进入森林的方式）有关。研究结果将有助于更好地了解森林多样性和结构复杂性如何相互作用并影响森林生产力。为了使森林工业继续或增加对加拿大经济的重要贡献，森林管理必须适应新的现实，例如基于生态系统的管理和全球变化。自然和人为干扰将继续增加对加拿大森林的压力。更好地了解林分结构和生长，可以评估如何最好地构建森林，以确保它们能够抵御预计的压力。