Secondary forests are a prominent component of tropical landscapes, and they constitute a major atmospheric carbon sink. Rates of carbon accumulation are usually inferred from chronosequence studies, but direct estimates of carbon accumulation based on long-term monitoring of stands are rarely reported. Recent compilations on secondary forest carbon accumulation in the Neotropics are heavily biased geographically as they do not include estimates from the Guiana Shield. We analysed the temporal trajectory of aboveground carbon accumulation and floristic composition at one 25-ha secondary forest site in French Guiana. The site was clear-cut in 1976, abandoned thereafter, and one large plot (6.25 ha) has been monitored continuously since. We used Bayesian modeling to assimilate inventory data and simulate the long-term carbon accumulation trajectory. Canopy change was monitored using two aerial lidar surveys conducted in 2009 and 2017. We compared the dynamics of this site with that of a surrounding old-growth forest. Finally, we compared our results with that from secondary forests in Costa Rica, which is one of the rare long-term monitoring programs reaching a duration comparable to our study. Twenty years after abandonment, aboveground carbon stock was 64.2 (95% credibility interval 46.4, 89.0) Mg C/ha, and this stock increased to 101.3 (78.7, 128.5) Mg C/ha 20 yr later. The time to accumulate one-half of the mean aboveground carbon stored in the nearby old-growth forest (185.6 [155.9, 200.2] Mg C/ha) was estimated at 35.0 [20.9, 55.9] yr. During the first 40 yr, the contribution of the long-lived pioneer species Xylopia nitida, Goupia glabra, and Laetia procera to the aboveground carbon stock increased continuously. Secondary forest mean-canopy height measured by lidar increased by 1.14 m in 8 yr, a canopy-height increase consistent with an aboveground carbon accumulation of 7.1 Mg C/ha (or 0.89 Mg C·ha-1 ·yr-1 ) during this period. Long-term AGC accumulation rate in Costa Rica was almost twice as fast as at our site in French Guiana. This may reflect higher fertility of Central American forest communities or a better adaptation of the forest tree community to intense and frequent disturbances. This finding may have important consequences for scaling-up carbon uptake estimates to continental scales.

中文翻译：

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与新热带地区的其他地区相比，圭亚那的次生森林碳积累速度慢。

次生林是热带景观的重要组成部分，它们构成了主要的大气碳汇。通常从时间序列研究中推断出碳积累的速率，但是很少报告基于对林分的长期监测得出的碳积累的直接估算值。关于新热带地区次生林碳积累的最新汇编在地理上存在严重偏差，因为它们不包括圭亚那盾构的估算。我们分析了法属圭亚那一个25公顷次生林地上地上碳积累和植物区系的时间轨迹。该场地于1976年被砍伐，之后被废弃，此后一直监视着一个大片土地（6.25公顷）。我们使用贝叶斯建模来吸收库存数据并模拟长期碳积累轨迹。我们在2009年和2017年进行了两次空中激光雷达测量，监测了冠层的变化。我们将该地点的动态与周围的老树森林进行了比较。最后，我们将研究结果与哥斯达黎加的次生林进行了比较，这是罕见的长期监测计划之一，其持续时间与我们的研究相当。废弃20年后，地上碳储量为64.2 Mg C / ha（95％可信区间46.4，89.0），此碳储量在20年后增加到101.3（78.7，128.5）Mg C / ha。积聚在附近的老生长森林中的平均地上碳的一半（185.6 [155.9，200.2] Mg C / ha）的时间估计为35.0 [20.9，55.9]年。在最初的40年中，长寿命的先驱物种Xylopia nitida，Goubia glabra，Laetia procera的地上碳储量不断增加。在8年中，用激光雷达测得的次生林平均冠层高度增加了1.14 m，冠层高度的增加与在此期间地上碳的积累为7.1 Mg C / ha（或0.89 Mg C·ha-1·yr-1）一致。期。哥斯达黎加的长期AGC积累率几乎是我们在法属圭亚那的站点的两倍。这可能反映了中美洲森林群落的肥力较高，或者森林树木群落对强烈和频繁干扰的更好适应。这一发现可能会对将碳吸收估算规模扩大到大陆规模产生重要影响。在此期间，冠层高度的增加与地面上的7.1 Mg C / ha（或0.89 Mg C·ha-1·yr-1）的碳积累一致。哥斯达黎加的长期AGC积累率几乎是我们在法属圭亚那的站点的两倍。这可能反映了中美洲森林群落的肥力较高，或者森林树木群落对强烈和频繁干扰的更好适应。这一发现可能会对将碳吸收估算规模扩大到大陆规模产生重要影响。在此期间，冠层高度增加与地面上的7.1 Mg C / ha（或0.89 Mg C·ha-1·yr-1）的碳积累一致。哥斯达黎加的长期AGC积累率几乎是我们在法属圭亚那的站点的两倍。这可能反映了中美洲森林群落的肥力更高，或者森林树木群落对强烈和频繁干扰的更好适应。这一发现可能会对将碳吸收估算规模扩大到大陆规模产生重要影响。