Relevance and magnitude of 'Blue Carbon' storage in mangrove sediments: Carbon accumulation rates vs. stocks, sources vs. sinks
Relevance and magnitude of 'Blue Carbon' storage in mangrove sediments: Carbon accumulation rates vs. stocks, sources vs. sinks
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DOI：
10.1016/j.ecss.2020.107027
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发表时间：
2020-12-05
影响因子：
2.8
通讯作者：
Jennerjahn, Tim C.
中科院分区：
文献类型：
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作者：
Jennerjahn, Tim C.
红树林生态系统储存了大量的“蓝碳”，特别是在沉积物中。过去十年的研究强调了红树林碳储存在减缓气候变化方面的定量意义，主要是通过确定碳储量并计算红树林退化造成的潜在二氧化碳排放量。然而，虽然这种方法侧重于可能因降解而损失的碳总量，但它未能捕获每年封存的碳量。因此，红树林沉积物中的碳积累也需要考虑在内。这项研究（i）解释了碳储量和碳积累率（CAR）之间的差异，（ii）解决了碳储存的地理变化和潜在因素，（iii）评估了红树林沉积物中“蓝碳”封存的全球相关性。结果表明，减少单个系统碳储存估算的不确定性需要一组涵盖系统内变异性的代表性数据。印度尼西亚的一个例子表明，碳储量高的红树林生态系统的碳排放量可能较低，反之亦然。因此，可以想象，矿物沉积物、有机质和养分异地供应较多的沿海环境环境大多具有低碳储量，但碳排放量较高。由于这些环境占全球红树林面积的 80% 以上，因此它们在长期碳储存方面最为重要。碳储量是衡量生态系统退化或完全损失情况下“脆弱性潜力”的指标，而碳储量则是衡量红树林生态系统碳储存“缓解潜力”的指标。本研究中根据 CAR 估计的红树林沉积物中的全球碳储量为 32 Tg yr(-1)，处于全球预算范围的上限（14.6-31.1 Tg yr(-1)，平均 22.9 Tg yr(-1)）。它强调红树林碳汇可能比以前认为的要大，但全球平均 CAR 233 +/- 280 g C m(2) yr(-1) 的巨大变化也表明需要进一步的数据。
Mangrove ecosystems store large amounts of 'Blue Carbon', in particular in the sediment. Research in the past decade has emphasized the quantitative significance of carbon storage in mangrove forests in climate change mitigation, mainly by determining carbon stocks and calculating potential CO2 emissions caused by mangrove degradation. However, while this approach focuses on the total amount of carbon that can be lost to degradation, it fails to capture the amount that is sequestered annually. Therefore, carbon accumulation in mangrove sediments also needs to be taken into account. This study (i) explains the differences between carbon stocks and carbon accumulation rates (CAR), (ii) it addresses the geographical variation of carbon storage and underlying factors and (iii) it assesses the global relevance of 'Blue Carbon' sequestration in mangrove sediments. Results indicate that reducing uncertainties in carbon storage estimates of individual systems requires a representative set of data that covers within-system variability. An example from Indonesia illustrates that a mangrove ecosystem with a high C stock can have a low CAR and vice versa. It is therefore conceivable that coastal environmental settings with high allochthonous supply of mineral sediment, organic matter and nutrients mostly have low carbon stocks, but high CARs. As these settings represent >80% of the global mangrove area they are most important in terms of long-term carbon storage. While a C stock is a measure of the "vulnerability potential" in the case of ecosystem degradation or total loss, a CAR is rather a measure of the "mitigation potential" of carbon storage in mangrove ecosystems. The global carbon storage in mangrove sediments of 32 Tg yr(-1) estimated from CARs in this study is at the upper end of the range of global budgets (14.6-31.1 Tg yr(-1), mean 22.9 Tg yr(-1)). It highlights that the mangrove carbon sink may be larger than previously thought, but the high variation in the global average CAR of 233 +/- 280 g C m(2) yr(-1) also indicates the need for further data.