Forest degradation is widespread around the world, due to multiple factors such as unsustainable logging, agriculture, invasive species, fire, fuelwood gathering, and livestock grazing. In the Brazilian Amazon forest degradation from August 2006 to July 2016 reached 1,1869,800 ha. The processes of forest degradation are still poorly understood, being a missing component in anthropogenic CO2 emission estimates in tropical forests. In this work, we analyzed temporal trajectories of forest degradation from August 2006 to July 2016 in the Brazilian Amazon and assessed their impact on the regional carbon balance. We combined the degradation process with deforestation-related processes (clear-cut deforestation and secondary vegetation dynamics), using the spatially-explicit INPE-EM carbon emission model. The trajectory analysis showed that 13% of the degraded area ended up being cleared and converted in the period and 61% of the total degraded area experienced only one event of degradation throughout the whole period. Net emissions added up to 5.4 GtCO2, considering the emissions from forest degradation and deforestation, absorption from degraded forest recovery, and secondary vegetation dynamics. The results show an increase in the contribution of forest degradation to net emissions towards the end of the period, related to the decrease in clear-cut deforestation rates, decoupled from the forest degradation rates. The analysis also indicates that the regeneration of degraded forests absorbed 1.8 GtCO2 from August 2006 and July 2016 – a component typically overlooked in the regional carbon balance.

中文翻译：

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巴西亚马逊地区森林退化造成的CO ₂排放

由于不可持续的伐木、农业、入侵物种、火灾、薪柴收集和牲畜放牧等多种因素，森林退化在世界各地普遍存在。2006 年 8 月至 2016 年 7 月，巴西亚马逊森林退化面积达 1,1869,800 公顷。森林退化的过程仍然知之甚少，是热带森林人为二氧化碳排放估计中的一个缺失部分。在这项工作中，我们分析了 2006 年 8 月至 2016 年 7 月巴西亚马逊地区森林退化的时间轨迹，并评估了它们对区域碳平衡的影响。我们使用空间明确的 INPE-EM 碳排放模型将退化过程与森林砍伐相关过程（砍伐森林和次生植被动态）相结合。轨迹分析表明，13% 的退化区域在此期间最终被清除和转化，61% 的退化区域在整个期间仅经历了一次退化事件。考虑到森林退化和森林砍伐造成的排放、退化森林恢复的吸收以及次生植被动态，净排放加起来达到 5.4 GtCO2。结果显示，到该时期结束时，森林退化对净排放量的贡献有所增加，这与森林砍伐率的下降有关，与森林退化率脱钩。分析还表明，从 2006 年 8 月到 2016 年 7 月，退化森林的再生吸收了 1.8 GtCO2——这是区域碳平衡中通常被忽视的一个组成部分。