Climate change and water use: can increase diversity help protect forests?

该研究项目是基于我们的合作伙伴和森林管理人员对气候变化对森林的影响的预测和缓解战略，以限制由于水压力及其对加拿大森林生产力的影响而造成的预期死亡率所表达的需求。** 事实上，本项目开展的研究将大大有助于减轻加拿大森林面临的一些最重要威胁的影响：由于无法迁移，树种多样性减少和适应不良，加上气候变化导致干旱期增加。** 该项目的主要科学目标是评价经常被引用但证明不充分的假设，即森林多样性将缓冲缺水对生产力、特别是死亡率的不利影响。这是一个高度战略性的假设，因为加拿大预计的气候变化会导致降水量的变化和不确定性。它也将很容易转化为有管理的天然林和植树造林的适应战略。此外，我们将评估气候变化后树木适应不良造成的死亡率增加对森林生产力的影响，这在很大程度上是未知的，目前管理者和政府也没有考虑到这一点。为了做到这一点，我们使用了实验方法，受益于我们的树木多样性实验网络（IDENT），以及使用永久森林地块数据的观察方法。该实验方法将利用稳定同位素（氘）追踪树木的吸水情况，并利用遥感（无人机）对树叶温度（热感相机）和空间树冠组织进行监测，以跟踪在高度受控的树木多样性实验（包括水分胁迫处理）中的用水和蒸散情况。观测分析将受益于我们在魁北克的大型永久性地块网络以及全球森林生物多样性倡议，包括世界上所有森林生物群落的100多万个森林地块。

This research project is strongly grounded on the needs expressed by our partners and by forest managers for predictions on the impacts of climate change on forests, and mitigation strategies to limit the expected mortality due to water stress and its effect of the productivity of Canadian forests. **Indeed, the research developed in this project will contribute significantly to mitigating the impacts of some of the most important threats to Canadian forests: decreasing diversity and maladaptation of tree species from failure to migrate, combined with increasing periods of drought due to changes in climate. **The main scientific objective of the project is to evaluate the often cited but poorly demonstrated hypothesis that forest diversity will buffer the negative impacts of water stress on productivity, especially mortality. This is a highly strategic hypothesis given the expected changes, and uncertainty, in precipitation from projected climate change in Canada. It will also be easily translated into adaptation strategies for both managed natural forests and tree plantations.**Furthermore, we will evaluate the size of the impact that increased mortality caused by the maladaptation of trees following climate change will have on forest productivity, which is largely unknown at this time, and not accounted for at present by managers and governments.**To do so, we use both an experimental approach, benefiting from our network of tree diversity experiments (IDENT), as well as an observational approach using data from permanent forest plots. The experimental approach will make use of a stable isotope (deuterium) to trace water uptake in trees, as well as remote sensing (drones) of leaf temperatures (thermal cameras) and canopy organization in space, to track water use and evapo-transpiration, in highly controlled tree diversity experiments that include water stress treatments. Observational analyses will benefit from our network of large permanent plots in Québec, as well as the Global Forest Biodiversity initiative, encompassing over 1 million forest plots across all forested biomes of the world.******