Explaining links between structure, albedo and nitrogen availability in forests using LiDAR and modelling

使用激光雷达和建模解释森林结构、反照率和氮可用性之间的联系

• 批准号: RGPIN-2016-06247
• 负责人: Béland, Martin
• 金额: $ 1.68万
• 依托单位: Université Laval
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=710230
• 关键词: Explaining; links; between; structure; albedo

Forest canopies are complex arrays of leaves with different angles, density, morphological features and photosynthetic capacity. Understanding the appropriate level of model complexity and applying the mathematics to compute gas exchanges accurately remains an important topic of biosphere-atmosphere interactions. For example, current models of global photosynthesis remain highly uncertain, ranging between 100 and 170 PgC, and this is the primary input into ecosystem, carbon cycling and coupled climate models. We need to do better if we are to make credible predictions about the response of forests to changing climate and potential feedbacks with the climate. Understanding the scale sensitive mechanisms driving CO2 assimilation by trees also has economic ramifications considering the ratified role of forests as credits in future carbon market schemes. The aim of this research program is to use LiDAR technology to investigate how leaves in a canopy function together across strong environmental gradients to determine CO2 and energy exchanges with the atmosphere. LiDAR instruments use millions of laser pulses emitted in a scanning motion to determine the 3D position of objects in their field of view. This technology allows detailed descriptions of the geometry of forest canopies, including the location and density of foliage. Such descriptions allow us to simulate the interaction of sun light (the energy source driving photosynthesis) and other abiotic variables with plant canopies in a virtual vegetation lab'. The approach has the potential for transforming the way we consider canopy structure by moving away from simple descriptors, like tree height and crown size, towards community arrangement based descriptors relating to photosynthetic production. This new knowledge will contribute significantly to our capacity to predict the effect of global environmental changes on forests, and on the role of forest responses in feedback loops with climate. This will lead to better informed decisions regarding Canada's energy challenges of the 21st century.

林冠是由不同角度、密度、形态特征和光合能力的叶片组成的复杂阵列。理解模型复杂性的适当水平并应用数学方法准确计算气体交换仍然是生物圈-大气相互作用的重要课题。例如，目前的全球光合作用模型仍然高度不确定，范围在100至170 PgC之间，这是生态系统、碳循环和耦合气候模型的主要输入。如果我们要对森林对气候变化的反应和对气候的潜在反馈做出可信的预测，我们就需要做得更好。考虑到森林在未来碳市场计划中作为信用额的批准作用，了解推动树木吸收二氧化碳的规模敏感机制也具有经济影响。该研究项目的目的是利用激光雷达技术研究冠层中的叶子如何在强环境梯度下共同发挥作用，以确定二氧化碳和与大气的能量交换。LiDAR仪器使用数百万个激光脉冲在扫描运动中发射，以确定物体在其视野中的3D位置。这项技术可以详细描述森林树冠的几何形状，包括树叶的位置和密度。这样的描述使我们能够在虚拟植被实验室中模拟阳光（驱动光合作用的能量来源）和其他非生物变量与植物冠层的相互作用。这种方法有可能改变我们考虑冠层结构的方式，从简单的描述符，如树高和树冠大小，对社区安排有关光合生产的描述符。这一新知识将大大有助于提高我们预测全球环境变化对森林的影响以及森林应对措施在气候反馈回路中的作用的能力。这将导致对加拿大21世纪世纪的能源挑战作出更明智的决定。