Warming temperatures and droughts are driving widespread forest dieback and growth decline worldwide. In forests experiencing dieback, declining trees may exhibit altered climate memory of growth, indicative of physiological impairment. Thus, we evaluated climate-growth responses of trees in four drought-disturbed forests dominated either by gymnosperms (Abies alba, Pinus sylvestris) or angiosperms (Fagus sylvatica, Quercus humilis) in Northern Spain, where we compared responses of declining (heavily defoliated) and non-declining (slightly or not defoliated) trees. To disentangle the effects of forest dieback and past climate on tree growth, we applied the stochastic antecedent modeling (SAM) framework to annual tree-ring widths to quantify climatic memory. Declining trees had lower recent growth than non-declining conspecifics. All species responded positively to precipitation and temperature, independent of their vigor class, except for declining silver fir (A. alba) and European beech (F. sylvatica) individuals, which showed a negative effect of warmer temperatures on growth. Declining trees of these two species were also more sensitive to recent temperature and precipitation conditions, whilst climatic conditions further into the past were more important for non-declining trees. Silver fir and European beech from both vigor classes were also coupled to climate conditions during markedly different seasons, with dry summer conditions particularly affecting declining trees. Declining and non-declining Scots pine (P. sylvetris) and pubescent oak (Q. humilis) trees did not show different responses to past climate. While drought-triggered dieback differentially impacted silver fir and European beech individuals, Scots pine and pubescent oak trees suffered from a chronic process of loss in tree growth and vigor. Our results highlight the differences in climate sensitivity and climate memory of tree growth in forests experiencing ongoing dieback.

气温升高和干旱正在推动世界范围内广泛的森林枯死和生长下降。在经历枯萎的森林中，衰退的树木可能会表现出对生长的气候记忆改变，表明生理受损。因此，我们评估了以裸子植物（Abies alba、Pinus sylvestris）或被子植物（Fagus sylvatica、Quercus humilis）为主的四个干旱森林中树木的气候生长响应) 在西班牙北部，我们比较了衰退（严重落叶）和非衰退（轻微或未落叶）树木的反应。为了解决森林枯死和过去气候对树木生长的影响，我们将随机先行模型 (SAM) 框架应用于年轮宽度以量化气候记忆。下降的树木最近的增长低于非下降的同种。所有物种都对降水和温度做出积极反应，与它们的活力等级无关，除了衰退的银杉 ( A. alba ) 和欧洲山毛榉 ( F. sylvatica) 个体，这表明温度升高对生长有负面影响。这两个物种的衰退树木对近期的温度和降水条件也更敏感，而过去的气候条件对未衰退的树木更为重要。两种活力等级的银杉和欧洲山毛榉在明显不同的季节也与气候条件相结合，夏季干燥的条件特别影响树木的衰退。衰退和非衰退的苏格兰松 ( P. sylvtris ) 和短柔毛橡树 ( Q. humilis) 树木对过去的气候没有表现出不同的反应。虽然干旱引发的枯死对银杉和欧洲山毛榉个体的影响不同，但苏格兰松树和短柔毛橡树却遭受了树木生长和活力的慢性丧失。我们的研究结果强调了在经历持续枯萎的森林中树木生长在气候敏感性和气候记忆方面的差异。