Abstract Plantations of Mediterranean pines will face warmer and drier climate conditions during the 21st century. However, we lack field assessments of how severe droughts could threaten the viability of many of these plantations, often located at xeric sites and lacking adaptive management measures such as thinning. In this work, we related radial-growth variability to recent defoliation, to evaluate the resilience and vulnerability of Maritime pine (Pinus pinaster) plantations from xeric sites in south-eastern Spain to three recent droughts (1995, 2005, and 2012). Tree diameter and growth resistance after the most severe drought, which occurred in 1995, were positively related to growth. In addition, the current defoliation level, a proxy for tree vigor, was related to growth, decreasing as tree-to-tree competition increased. These findings indicate that increasing drought will reduce growth and increase the needle loss and mortality rate across many dense pine plantations in the Mediterranean Basin, suggesting that they are more prone to die. Thus, limited resilience of plantations may explain their higher defoliation and indicate that future severe droughts could lead to widespread dieback and high mortality at marginal sites. Therefore, if effective management is not implemented, warmer and drier conditions will likely threaten the viability of many of these drought-prone plantations and their ability to deliver key ecosystem services.

中文翻译：

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面对气候干燥的转变，松树种植园的复原力高，但生存能力低

摘要 21 世纪地中海松林将面临更加温暖干燥的气候条件。然而，我们缺乏对严重干旱如何威胁许多这些人工林的生存能力的实地评估，这些人工林通常位于干旱地区，缺乏适应性管理措施，如间伐。在这项工作中，我们将径向生长变异性与最近的落叶联系起来，以评估来自西班牙东南部干旱地区的海松（Pinus pinaster）种植园对最近的三场干旱（1995、2005 和 2012）的恢复力和脆弱性。1995 年发生的最严重干旱后的树木直径和生长抗性与生长呈正相关。此外，当前的落叶水平（树木活力的代表）与生长有关，随着树木间竞争的增加而减少。这些发现表明，在地中海盆地的许多茂密的松树种植园中，干旱加剧将减少生长并增加针叶损失和死亡率，这表明它们更容易死亡。因此，种植园的有限恢复力可能解释了它们落叶率较高的原因，并表明未来的严重干旱可能导致边缘地区的广泛枯死和高死亡率。因此，如果不实施有效管理，更温暖和更干燥的条件可能会威胁到许多这些易旱种植园的生存能力及其提供关键生态系统服务的能力。种植园恢复力有限可能解释了它们落叶率较高的原因，并表明未来的严重干旱可能导致边缘地区的广泛枯萎和高死亡率。因此，如果不实施有效管理，更温暖和更干燥的条件可能会威胁到许多这些易旱种植园的生存能力及其提供关键生态系统服务的能力。种植园恢复力有限可能解释了它们落叶率较高的原因，并表明未来的严重干旱可能导致边缘地区的广泛枯萎和高死亡率。因此，如果不实施有效管理，更温暖和更干燥的条件可能会威胁到许多这些易旱种植园的生存能力及其提供关键生态系统服务的能力。