Global mangrove loss is occurring from deforestation and extreme climatic events, but changes to the coastal carbon cycle following mangrove mortality and/or loss are not well understood. In 2015/2016, a massive climate‐driven mangrove dieback event occurred over ~ 1000 km of Australian coastline. To assess carbon loss following mortality, carbon fluxes in adjacent living and dead forest areas were compared 8 and 20 months postforest dieback. Dead areas experienced an increase in soil CO₂ efflux by ~ 189%, and a decrease in oceanic dissolved inorganic carbon (DIC) outwelling of ~ 50% relative to living areas. DIC outwelling (predominantly carbonate alkalinity) and soil CO₂ efflux accounted for 81% and 16% of losses from the living forest, in comparison to 51% and 47%, respectively, from the dead forest. The dieback drove a shift from a dominance of oceanic carbon outwelling to increased atmospheric CO₂ emissions and decreased alkalinity exports. This shift was likely driven by increased oxygen sediment permeation and the loss of mangrove net primary productivity. Combining our new observations with literature data, we found a logarithmic relationship between soil carbon loss and time since mangrove loss. Using this relationship, we estimate ongoing global carbon losses from historical mangrove deforestation and dieback could be 13.7 ± 9.4 Tg C yr⁻¹, which is eightfold higher than previous estimates and offsets global mangrove carbon burial by ~ 60%. Even if no future deforestation occurred, we estimate ongoing carbon losses to the atmosphere and ocean from current global mangrove losses of 27 Tg C over the next 30 yr.

中文翻译：

---

红树林流失后沿海碳循环变化

全球红树林的丧失是由于森林砍伐和极端气候事件而发生的，但是人们对红树林的死亡和/或丧失后沿海碳循环的变化知之甚少。在2015/2016年，约有1000公里的澳大利亚海岸线发生了大规模的气候驱动型红树林死亡事件。为了评估死亡后的碳损失，比较了森林枯死后8个月和20个月内邻近的活林和枯林区域的碳通量。死区相对于居住区的土壤CO ₂外排量增加了约189％，海洋溶解无机碳（DIC）外向减少了约50％。DIC外溢（主要是碳酸盐碱度）和土壤CO ₂外排占活林损失的81％和16％，相比之下，死林损失分别为51％和47％。死亡使海洋碳占主导地位转向大气CO ₂排放增加和碱度出口减少。这种变化很可能是由于氧气沉积物渗透增加和红树林净初级生产力的丧失所致。将我们的新发现与文献数据相结合，我们发现了土壤碳损失与红树林损失以来的时间之间的对数关系。利用这种关系，我们估计历史红树林砍伐和荒漠化造成的持续全球碳损失可能是13.7±9.4 Tg C yr ^-1，比先前的估算高出八倍，使全球红树林的碳埋葬量减少了约60％。即使未来没有发生森林砍伐，我们也估计在未来30年中，当前全球红树林的碳损失为27 Tg C，从而持续向大气和海洋造成碳损失。