Over recent decades, climate change has been particularly severe in the Mediterranean basin, where the intensity and frequency of drought events have had a significant effect on tree growth and mortality. In this context, differences in structural and physiological strategies between tree species could help to mitigate the damage inflicted by climate variability and drought events. Here, we used dendroecological approaches to observe common associations (synchrony) between indexed ring width in Pinus pinea and P. pinaster, as a measure of degree of dependence on climate variation or growth sensitivity to climate, as well as to analyze species growth responses to drought events through the Lloret’s indices of resistance, recovery and resilience. Based on data from 75 mixed and pure plots installed in the Northern Plateau of Spain, we used modeling tools to detect the effect of the mixture, along with climate and stand-related variables, on the short-term responses and long-term growth sensitivity to climate. Our results showed a trade-off between resistance and recovery after the drought episodes. In addition, different attributes of tree species, such as age and size as well as stand density seemed to act synergistically and compensate drought stress in different ways. The presence of age and quadratic mean diameter as covariates in the final synchrony model for P. pinaster reflected the influence of other variables as modulators of growth response to climate. Furthermore, differences in growth synchrony in mixed and monospecific composition suggested the existence of interactions between the two species and some degree of temporal niche complementarity. In mixed stands, P. pinaster exhibited a lower sensitivity to climate than in monospecific composition, whereas P. pinea enhanced its resistance to extreme droughts. These results allowed us to identify the species-specific behavior of P. pinea and P. pinaster to mitigate vulnerability to climate-related extremes.

中文翻译：

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松和松属混交林和单种林对气候的短期和长期生长响应

近几十年来，地中海盆地的气候变化尤为严重，干旱事件的强度和频率对树木生长和死亡率产生了重大影响。在这种情况下，树种之间结构和生理策略的差异可能有助于减轻气候变异和干旱事件造成的损害。在这里，我们使用树木生态学方法观察松树和松树的索引环宽度之间的共同关联（同步），作为对气候变化的依赖程度或对气候的生长敏感性的度量，以及分析物种生长对气候变化的响应通过 Lloret 的抗性、恢复和复原力指数来预测干旱事件。基于安装在西班牙北部高原的 75 个混合和纯地块的数据，我们使用建模工具来检测混合物以及气候和林分相关变量对气候的短期响应和长期增长敏感性的影响。我们的结果显示了干旱事件后抗性和恢复之间的权衡。此外，树种的不同属性，如年龄和大小以及林分密度似乎协同作用并以不同方式补偿干旱胁迫。在 P. pinaster 的最终同步模型中，年龄和二次平均直径作为协变量的存在反映了其他变量作为生长对气候响应的调节因子的影响。此外，混合和单种组成中生长同步性的差异表明这两个物种之间存在相互作用，并且存在一定程度的时间生态位互补性。在混合看台上，P. pinaster 对气候的敏感性低于单一成分，而 P. pinea 增强了其对极端干旱的抵抗力。这些结果使我们能够确定 P. pinea 和 P. pinaster 的物种特异性行为，以减轻对气候相关极端事件的脆弱性。