Modelling the effects of environmental conditions on wood physico-mechanical properties

木材的物理力学性质是树木的关键功能性状，影响树木对机械刺激的结构抗性和木质部汁液的传导性。木材细胞生产的发展限制，以及优化树木的机械稳定性和水力效率的需要，导致木材属性(即幼龄和成熟木材)的独特径向模式，影响最终产品性能。然而，环境条件的影响及其与营林栽培处理的潜在相互作用对这些变异模式的影响仍然知之甚少。这项研究计划的长期动机是开发模型，帮助了解和预测木材属性在树干内的分布，目的是表征当前森林资源对各种最终用途的适宜性，并预测环境条件和营林做法对木材产品流动和价值的影响。基于对木材形成的环境驱动因素的更好的理解，我们的目标是产生新一代模型，能够预测与森林管理者相关的尺度上的木材性质的变化。具体地说，我们的目标是1)了解森林干扰，如火灾和林分动态对木材性质的影响；2)量化木材性质对气候变量的响应；3)扩大从树轮到森林景观等不同等级变化水平之间的预测。为了实现这一目标，我们的总体方法包括将木材性质的变异来源从细胞壁的规模划分到树木、林分和森林景观的规模。我们将使用机会主义抽样方法，研究树木的生长历史，以量化它们所处的环境条件的影响。我们将对从安大略省北部到纽芬兰的五个地区的树木进行采样，这将使我们能够调查水可获得性对北美北部针叶林中黑云杉木材性质的影响。木髓-树皮模型将产生密度、尺寸稳定性、强度和硬度等木材属性，这些属性是木质部结构的生理和最终用途适宜性的关键决定因素。这笔赠款将用于资助学生在加拿大缺乏合格人才的领域进行培训。随着森林部门目前从商品生产转向附加值生产，人们对使用能够在多个尺度上预测木材质量变化的模型非常感兴趣。在该计划内开发的模型和软件工具不仅将为整合我们最新的知识提供一个可识别的场所，而且还将有助于为价值链中更早的决策提供信息，从而提高这一对加拿大经济至关重要的部门未来的效率。

Wood physico-mechanical properties are key functional traits of trees that influence both their structural resistance to mechanical stimuli and the conductivity of sap in the xylem. Developmental constraints on wood cell production, and the need for optimising both the mechanical stability of trees and their hydraulic efficiency result in distinctive radial patterns of wood properties (i.e. juvenile and mature wood) that influence end-product performance. However, the effects of environmental conditions, and their potential interactions with silvicultural treatments, on these patterns of variation remain poorly understood. The long-term motivation for this research program is to develop models that can help understand and predict the within-stem distribution of wood properties with the aim of characterizing the suitability of the current forest resource for various end-uses and anticipating the impact of environmental conditions and silvicultural practices on wood product flows and value. Based on an improved understanding of the environmental drivers of wood formation, we aim to produce a new generation of models that can predict the variation of wood properties at a scale that is relevant to forest managers. Specifically, we will aim to 1) understand the effects of forest disturbances, such as fire, and stand dynamics on wood properties; 2) quantify the response of wood properties to climatic variables, and 3) scale up predictions between the hierarchical levels of variation, from the tree-ring to forest landscapes. To achieve this, our overall approach consists of partitioning sources of variation in wood properties from the scale of the cell wall to that of trees, stands and forest landscapes. We will use an opportunistic sampling approach whereby we will examine the growth history of trees to quantify the effects of the environmental conditions to which they were exposed. We will sample trees in five regions spanning from Northern Ontario to Newfoundland, which will allow us to investigate the effects of water availability on black spruce wood properties across the North American boreal forest. Pith-to-bark models will be produced of wood properties such as density, dimensional stability, strength and stiffness, which are key determinants of xylem structure both physiologically and in terms of the suitability for end-use. The grant will be used to fund student training in a field which has a shortage of qualified personnel in Canada. With the forest sector currently shifting from commodity to value-added production, there is significant interest in using models that can predict wood quality variation at multiple scales. The models and software tools developed within this program will not only provide an identifiable locus for the integration of our most up-to-date knowledge, but they will also help inform decision-making earlier in the value chain, and thus improve the future efficiency of this important sector for the Canadian economy.