AimIncreased tree mortality linked to droughts and fires is occurring across temperate regions globally. Vegetation recovery has been widely reported; however, less is known about how disturbance may alter forests structurally and functionally across environmental gradients. We examined whether dry forests growing on low‐fertility soils were more resilient to coupled extreme drought and severe fire owing to lower tree mortality rates, higher resprouting success and persistence of juveniles relative to wetter forests on more fertile soils.LocationFire‐tolerant eucalypt forests of temperate southeastern Australia.Time period2020–2023.Major taxa studiedEucalyptus, Corymbia, Angophora.MethodsDemographic surveys of tree mortality and regeneration in all combinations of dry/wet forest, fertile/less fertile substrates exposed to extreme drought and fire were conducted. We used Bayesian regression modelling to compare tree mortality, diameter, response traits, population structure and occurrence of fire scars between substrates/forest types.ResultsOverall mortality (20%–33%) and topkill (34%–41%) were within historically reported ranges for various forests and soil types. However, we observed an atypical trend of increased mortality and topkill in the largest trees, particularly when they had structural damage from past fires. Trees in wet forests on more fertile soils had the highest levels of mortality. Numbers of persistent resprouting juveniles were highest in dry forests on low‐fertility soils. Dry forests growing on low‐fertility soils appear more resilient to compound disturbances due to lower rates of mortality and higher rates of juvenile persistence. Wet forests on more fertile soils may experience greater demographic change due to higher mortality of small and large trees.Main conclusionsMesic forests on relatively fertile soils were found to be at relatively high risk of demographic change from compound disturbances. Combined, fire and drought are likely to reduce the number of large trees in affected areas, with consequences for forest carbon cycling and storage.

中文翻译：

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遭受巨大干扰的重发桉树林中的人口变化和大树损失

目标全球温带地区因干旱和火灾导致树木死亡率增加。植被恢复已得到广泛报道；然而，人们对干扰如何在环境梯度上改变森林的结构和功能知之甚少。我们研究了生长在低肥力土壤上的干燥森林是否比生长在更肥沃土壤上的湿润森林更能抵御极端干旱和严重火灾，因为树木死亡率较低，再发芽成功率较高，幼树的持久性也较高。澳大利亚东南部温带地区。时间段2020–2023。研究的主要类群桉树,珊瑚属,安格芙兰方法对暴露于极端干旱和火灾的干燥/潮湿森林、肥沃/贫瘠基质的所有组合中的树木死亡率和再生进行人口统计调查。我们使用贝叶斯回归模型来比较基质/森林类型之间的树木死亡率、直径、响应特征、种群结构和火痕发生情况。结果总死亡率 (20%–33%) 和顶杀率 (34%–41%) 在历史报告范围内各种森林和土壤类型的范围。然而，我们观察到最大的树木死亡率和枯死率增加的非典型趋势，特别是当它们因过去的火灾而受到结构性损坏时。土壤较肥沃的潮湿森林中的树木死亡率最高。在低肥力土壤的干燥森林中，持久再发芽幼体的数量最高。由于死亡率较低和幼年持续率较高，生长在低肥力土壤上的干燥森林似乎对复合干扰更具抵抗力。由于小树和大树的死亡率较高，土壤较肥沃的潮湿森林可能会经历更大的人口变化。主要结论发现土壤相对肥沃的湿森林因复合干扰而面临相对较高的人口变化风险。火灾和干旱可能会减少受影响地区大树的数量，从而对森林碳循环和储存产生影响。