Abstract Last decades increase in reported events of drought-induced tree mortality evidences how climate-change is transforming forest ecosystems all over the world. The parallel increase in human pressure over the land is also causing major changes in forest functioning but it remains unclear how these two driving forces interact between them. We combined tree-ring data with aboveground cover, leaf area index (LAI), soil variables, and the standardized precipitation evapotranspiration index (SPEI) as water availability indicator to disentangle the existence of linkages between contrasting Holm oak (Quercus ilex L. subsp. ballota [Desf.] Samp) land-use practices and its drought-induced decline and mortality. We selected ten sites covering different soil and climatic gradients, land-use practices (i.e., declining dehesas, DH; declining coppices, FRd; and healthy coppices, FRh), and tree vigour classes (i.e., living, affected, and dead trees) in Spain. DH sites presented lower tree coverage, soil water holding capacity and soil pH than coppice (FR) sites. Dead Holm oaks from DH sites were younger than living ones, whereas dead trees from FRd sites were smaller and showed lower growth rates than living ones. We also found that conservation of traditional land-use practices in FR sites, resulting in less understorey cover but more soil erosion (less nutrients and microbial biomass and more bare soil), may positively affect the growth plasticity and sensitivity to drought of Holm oak trees by alleviating inter-specific competition, but in detriment of vegetation cover and soil health. Further studies should evaluate whether what holds true for FRh sites regarding the maintenance of traditional land-use practices might also apply for healthy DH. In the face of drier and hotter scenarios, our results add robust evidences on how the modulation of the intensity of the traditional uses could be a useful tool to optimize ecosystem services in Mediterranean systems highly vulnerable to climate change.

中文翻译：

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土地利用实践（小树林和 dehesas）和管理强度调节圣栎生长对干旱的响应

摘要 过去几十年，干旱引起的树木死亡报告事件的增加证​​明了气候变化正在改变世界各地的森林生态系统。人类对土地的压力同时增加也导致森林功能发生重大变化，但目前尚不清楚这两种驱动力如何相互作用。我们将树木年轮数据与地上覆盖、叶面积指数 (LAI)、土壤变量和标准化降水蒸发蒸腾指数 (SPEI) 结合作为可用水指标，以解开对比圣栎 (Quercus ilex L. subsp.) 之间是否存在联系。 ballota [Desf.] Samp) 土地利用做法及其干旱引起的衰退和死亡率。我们选择了 10 个地点，涵盖不同的土壤和气候梯度、土地利用实践（即下降的 dehesas、DH；下降的矮林、FRd; 和健康的灌木丛，FRh）和西班牙的树木活力等级（即活的、受影响的和死树）。DH 地点的树木覆盖率、土壤持水能力和土壤 pH 值低于矮林 (FR) 地点。来自 DH 地点的死圣橡树比活橡树年轻，而来自 FRd 地点的死树更小，生长速度低于活橡树。我们还发现，在 FR 地点保护传统的土地利用做法，导致下层覆盖较少，但土壤侵蚀更多（养分和微生物生物量减少，裸露的土壤更多），可能会对霍尔姆橡树的生长可塑性和对干旱的敏感性产生积极影响通过减轻种间竞争，但不利于植被覆盖和土壤健康。进一步的研究应该评估 FRh 场地在维护传统土地利用实践方面的适用性是否也适用于健康的 DH。面对更干燥和更热的情景，我们的结果提供了强有力的证据，证明传统用途强度的调节如何成为优化极易受气候变化影响的地中海系统生态系统服务的有用工具。