Systematic forest networks of health monitoring have been established to follow changes in tree vigor and mortality. These networks often lack long-term growth data, but they could be complemented with tree ring data, since both defoliation and radial growth are proxies of changes in tree vigor. For instance, a severe water shortage should reduce growth and increase tree defoliation in drought-prone areas. However, the effects of climatic stress and drought on growth and defoliation could also depend on tree age. To address these issues, we compared growth and defoliation data with recent climate variability and drought severity in Abies pinsapo old and young trees sampled in Southern Spain, where a systematic health network (Andalucía Permanent Plot Network) was established. Our aims were: (i) to assess the growth sensitivity of old and young A. pinsapo trees and (ii) to test if relative changes in radial growth were related with recent defoliation, for instance, after severe droughts. We also computed the resilience indices to quantify how old and young trees recovered growth after recent droughts. Wet-cool conditions during the prior autumn and the current early summer improved the growth of old trees, whereas late-spring wet conditions enhanced the growth of young trees. Old trees were more sensitive to wet and sunny conditions in the early summer than young trees. Old and young trees were more responsive to the Standardized Precipitation-Evapotranspiration Index drought index of June–July and July–August calculated at short (one–three months) and mid (three–six months) time scales, respectively. Old trees presented a higher resistance to a severe drought in 1995 than young trees. A positive association was found between stand defoliation and relative growth. Combining monitoring and tree ring networks is useful for the detection of early warning signals of dieback in similar drought-prone forests.

中文翻译：

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西班牙南部冷杉冷杉林中气候，径向生长和落叶之间的联系

建立了系统的森林健康监测网络，以追踪树木活力和死亡率的变化。这些网络通常缺乏长期的生长数据，但是由于落叶和径向生长都是树木活力变化的代理，因此可以用树环数据进行补充。例如，严重缺水将减少干旱多发地区的生长并增加树木的落叶。但是，气候压力和干旱对生长和落叶的影响也可能取决于树龄。为了解决这些问题，我们将生长和落叶数据与近来冷杉的气候变异性和干旱严重程度进行了比较在西班牙南部采样了老树和幼树，在那里建立了系统的卫生网络（安达卢西亚永久性地块网络）。我们的目标是：（i）评估老年和幼年A. Pinapo的生长敏感性（ii）测试径向生长的相对变化是否与最近的落叶（例如，严重干旱后）有关。我们还计算了恢复力指数，以量化在近期干旱后老树和幼树如何恢复生长。前一个秋天和当前初夏的湿冷条件改善了老树的生长，而后春的潮湿条件则促进了幼树的生长。在初夏，老树比年轻树对潮湿和阳光充足的条件更为敏感。在短（一到三个月）和中期（三到六个月）的时间尺度上计算，老龄树和幼树对6月至7月和7月至8月的标准降水-蒸散指数干旱指数反应更快。1995年，老树比年轻树对干旱的抵抗力更高。林分落叶与相对生长之间存在正相关关系。将监视网络和树环网络相结合对于检测类似干旱多发森林中的枯死预警信号很有用。