Evaluating variation in the sensitivity of tree growth, mortality, and biomass allocation to climate-induced moisture stress across the western boreal forest

加拿大西部北部森林地区从马尼托巴省一直延伸到育空地区，是全球重要的碳库。然而，近几十年来干旱加剧导致整个区域的森林碳损失，因为水分压力降低了生产力(减缓了树木的生长)并增加了死亡率。这些变化构成了重大威胁，因为变暖的气温和更大的干旱共同加剧了火灾风险，使树木容易受到虫害的攻击，减少了可销售木材的供应，并在碳储存释放到大气中时引发了破坏性的气候变化反馈。为了更好地了解这一森林地区的气候敏感性，我们的合作伙伴关系将建立并反复调查加拿大西部三大北方生态区的400个地点的网络。我们将使用来自地面小区、无人驾驶飞行器图像和陆地激光扫描的数据来(1)评估气候水分可获得性对个体树木生长和存活的影响如何在物种间、与局部竞争以及与场地水文学之间的差异；(2)研究气候水资源可获得性和局部竞争如何影响树冠内和地上生物量异速生长模型中的生长分配。这项研究将更清楚地了解目前数据有限的加拿大主要林区的森林和碳动态。为了确保成果被主要利益攸关方广泛采纳，我们将根据我们的发现开发一个免费可用的气候风险测绘工具。这一工具将使森林业的最终用户能够评估林木和碳储存对未来某一感兴趣地区未来干旱的脆弱性。彻底了解森林对区域气候压力的敏感性如何变化，是在整个加拿大西部林业部门制定和部署气候适应和缓解战略的关键一步。

Stretching from Manitoba to the Yukon, Canada's western boreal forest region represents a globally significant carbon pool. However, increases in aridity in recent decades have caused region-wide losses of forest carbon as moisture stress has both reduced productivity (slowed tree growth) and increased mortality. These changes pose a significant threat as warming temperatures and greater aridity together exacerbate the risk of fire, predispose trees to attack by insect pests, reduce supplies of merchantable timber, and trigger damaging climate change feedbacks when carbon stocks are released to the atmosphere. To better understand the climate sensitivity of this forest region, our partnership will establish and repeatedly survey a network of 400 sites across three major boreal ecozones in western Canada. We will use data from ground plots, unmanned aerial vehicle imagery, and terrestrial laser scanning to (1) evaluate how the effects of climatic water availability on the growth and survival of individual trees vary among species, with local competition, and with site hydrology; and (2) examine how climatic water availability and local competition influence partitioning of growth within crowns and in allometric models for aboveground biomass. This research will provide a clearer understanding of forest and carbon dynamics across a major Canadian forest region for which there is currently limited data. To ensure results are widely taken up by key stakeholders, we will develop a freely-available climate risk mapping tool based on our findings. This tool will allow end-users in the forest industry to assess the vulnerability of forest stands and carbon stocks to future drought across a given area of interest. A thorough understanding of how forests vary in their susceptibility to regional climate stress represents a critical step towards the development and deployment of climate adaptation and mitigation strategies across western Canada's forest sector.