Institute at Brown for Environment and Society, Brown University, Providence, RI, 02912, USA.
Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, 02912, USA.
Sci Rep. 2021 May 28;11(1):11279. doi: 10.1038/s41598-021-90576-x.
Field measurements demonstrate a carbon sink in the Amazon and Congo basins, but the cause of this sink is uncertain. One possibility is that forest landscapes are experiencing transient recovery from previous disturbance. Attributing the carbon sink to transient recovery or other processes is challenging because we do not understand the sensitivity of conventional remote sensing methods to changes in aboveground carbon density (ACD) caused by disturbance events. Here we use ultra-high-density drone lidar to quantify the impact of a blowdown disturbance on ACD in a lowland rain forest in Costa Rica. We show that the blowdown decreased ACD by at least 17.6%, increased the number of canopy gaps, and altered the gap size-frequency distribution. Analyses of a canopy-height transition matrix indicate departure from steady-state conditions. This event will initiate a transient sink requiring an estimated 24-49 years to recover pre-disturbance ACD. Our results suggest that blowdowns of this magnitude and extent can remain undetected by conventional satellite optical imagery but are likely to alter ACD decades after they occur.
实地测量表明，亚马逊和刚果盆地存在碳汇，但碳汇的成因尚不确定。一种可能性是，森林景观正在从先前的干扰中经历短暂的恢复。由于我们不了解常规遥感方法对干扰事件引起的地上碳密度（ACD）变化的敏感性，因此将碳汇归因于短暂恢复或其他过程具有挑战性。在这里，我们使用超高密度无人机激光雷达来量化哥斯达黎加低地雨林中一次倒伏干扰对 ACD 的影响。我们表明，倒伏至少降低了 ACD 的 17.6%，增加了林冠空隙的数量，并改变了空隙大小频率分布。林冠高度转换矩阵的分析表明，稳态条件已经偏离。该事件将引发一个短暂的碳汇，需要大约 24-49 年才能恢复干扰前的 ACD。我们的结果表明，这种规模和程度的倒伏可能会被传统卫星光学图像所忽略，但在发生几十年后，它们很可能会改变 ACD。
