Marchand William, Depardieu Claire, Campbell Elizabeth M, Bousquet Jean, Girardin Martin P
Institut National de l'Information Géographique et Forestière (IGN), Château des Barres, Nogent-sur-Vernisson, France.
Laurentian Forestry Centre, Natural Resources Canada, Canadian Forest Service, Québec, Québec, Canada.
Glob Chang Biol. 2025 Jul;31(7):e70330. doi: 10.1111/gcb.70330.
Severe drought increasingly threatens the resilience, productivity, and distribution of forest biomes worldwide. Understanding the evolution of tree drought resilience over the past century, along with its geographical and taxonomic relationships, is essential for predicting future forest dynamics. Using a tree-ring database from Canadian forests, encompassing 40,147 trees across 4558 plots and 23 species, we analyzed temporal and spatial patterns of drought resilience. We examined how leaf habit, prior drought exposure, and site- and tree-level factors influence growth resistance (immediate drought response), growth recovery (post-drought growth resumption), and overall resilience. Our findings indicate that most major Canadian tree species exhibit low and declining drought resilience. Mean temperature, moisture availability, and elevation emerged as critical factors in shaping tree responses to drought. At high elevation, drought impacts were buffered by cool temperatures, enabling trees to maintain stable growth rates. Deciduous species showed a significant decline in recovery and resilience throughout the 20th century, whereas evergreen species displayed stable but low resilience and recovery. Summer droughts particularly reduced resistance and recovery in deciduous species compared to evergreens. However, prior drought exposure mitigated negative drought responses over a tree's lifetime, suggesting an adaptive capacity in both evergreen and deciduous species. Older forests unaccustomed to severe droughts appear especially vulnerable, potentially leading to shifts in ecosystem composition and reduced biodiversity. The declining resilience of deciduous species, combined with the low resilience of evergreens, suggests major changes for Canadian forests, including reduced productivity and altered species composition. Our results emphasize the importance of proactive forest management strategies to preserve forest productivity and biodiversity in the context of a changing climate.
严重干旱日益威胁着全球森林生物群落的恢复力、生产力和分布。了解过去一个世纪树木抗旱恢复力的演变及其地理和分类关系，对于预测未来森林动态至关重要。利用来自加拿大森林的树木年轮数据库，该数据库涵盖了4558个地块的40147棵树和23个物种，我们分析了抗旱恢复力的时空模式。我们研究了叶片习性、先前的干旱暴露以及地点和树木水平的因素如何影响生长抗性（即时干旱响应）、生长恢复（干旱后生长恢复）和总体恢复力。我们的研究结果表明，加拿大的大多数主要树种表现出较低且不断下降的抗旱恢复力。平均温度、水分可利用性和海拔成为塑造树木对干旱响应的关键因素。在高海拔地区，凉爽的温度缓冲了干旱的影响，使树木能够保持稳定的生长速度。落叶树种在整个20世纪的恢复力和恢复能力显著下降，而常绿树种表现出稳定但较低的恢复力和恢复能力。与常绿树种相比，夏季干旱尤其降低了落叶树种的抗性和恢复能力。然而，先前的干旱暴露减轻了树木一生中干旱的负面响应，这表明常绿和落叶树种都具有适应能力。不习惯严重干旱的老龄森林显得特别脆弱，可能导致生态系统组成的变化和生物多样性的减少。落叶树种恢复力的下降，加上常绿树种恢复力较低，表明加拿大森林将发生重大变化，包括生产力下降和物种组成改变。我们的结果强调了积极的森林管理策略在气候变化背景下保护森林生产力和生物多样性的重要性。
