关于欧洲橡树为主的森林生态的大多数信息来自数百年来改变的森林,因为古老森林的残留物很少。旧森林的干扰和招募制度提供了有关森林动态及其对长期碳储存的影响的信息。在西班牙西北部的一个古老的橡树森林中,我们清点了三个地块,并从树冠类别(DBH≥5cm)的166棵活树和枯树中提取了岩心。我们根据树木的年轮宽度重建了过去500年的扰动动力学。我们还使用异速方程重建了过去的地上生物量(AGB)动态和最近的AGB积累率。从这些数据来看,我们提出了一种新的基于树木年轮的方法来估计AGB中储存的碳的年龄。最老的树至少有568年,使它成为迄今为止已知的最古老的精确年份的橡树,也是北半球最古老的阔叶树之一。所有地块都包含超过400年的树木。骚乱政权以小规模为主,频繁释放,只有一些更强烈的干扰,影响≤20%的树木。橡树的招募是可变的,但持续了500年。碳周转时间在153至229年之间,平均碳龄在108至167年之间。超过50%的AGB(150Mg·ha-1)持续≥100年,而多达21%的AGB(77Mg·ha-1)持续≥300年。低干扰率和低生产率保持了目前的树冠优势。在过去的500年中,没有管理或替代林分干扰导致了高度的森林稳定性,长的碳周转时间和长的平均碳年龄。观察到的动态和缺乏耐荫物种表明,橡树的优势可能会在未来继续。我们对无管理的老森林百年尺度的长期碳储存的估计强调了管理和自然干扰对全球碳循环的重要性。
Most information on the ecology of oak-dominated forests in Europe comes from forests altered for centuries because remnants of old-growth forests are rare. Disturbance and recruitment regimes in old-growth forests provide information on forest dynamics and their effects on long-term carbon storage. In an old-growth Quercus petraea forest in northwestern Spain, we inventoried three plots and extracted cores from 166 live and dead trees across canopy classes (DBH ≥ 5 cm). We reconstructed disturbance dynamics for the last 500 years from tree-ring widths. We also reconstructed past dynamics of above ground biomass (AGB) and recent AGB accumulation rates at stand level using allometric equations. From these data, we present a new tree-ring-based approach to estimate the age of carbon stored in AGB. The oldest tree was at least 568 years, making it the oldest known precisely-dated oak to date and one of the oldest broadleaved trees in the Northern Hemisphere. All plots contained trees over 400 years old. The disturbance regime was dominated by small, frequent releases with just a few more intense disturbances that affected ≤20% of trees. Oak recruitment was variable but rather continuous for 500 years. Carbon turnover times ranged between 153 and 229 years and mean carbon ages between 108 and 167 years. Over 50% of AGB (150 Mg·ha-1) persisted ≥100 years and up to 21% of AGB (77 Mg·ha-1) ≥300 years. Low disturbance rates and low productivity maintained current canopy oak dominance. Absence of management or stand-replacing disturbances over the last 500 years resulted in high forest stability, long carbon turnover times and long mean carbon ages. Observed dynamics and the absence of shade-tolerant species suggest that oak dominance could continue in the future. Our estimations of long-term carbon storage at centennial scales in unmanaged old-growth forests highlights the importance of management and natural disturbances for the global carbon cycle.