Fluvial organic carbon fluxes from oil palm plantations on tropical peatland
Fluvial organic carbon fluxes from oil palm plantations on tropical peatland
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DOI：
10.5194/bg-15-7435-2018
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发表时间：
2018-12-21
期刊：
影响因子：
4.9
通讯作者：
Page, Susan E.
中科院分区：
文献类型：
--
作者：
Cook, Sarah;Whelan, Mick J.;Page, Susan E.
完整的热带泥炭地是密集的长期碳库。然而，这些生态系统的未来安全面临着土地转换和广泛的泥炭地排水的风险。这可以加强泥炭的氧化，并将长期碳汇转化为重要的碳源。在东南亚，泥炭地上最大的土地用途是油棕榈种植园农业。在这里，我们给出了马来西亚沙捞越四个泥炭地油棕榈种植区排水中出口河流有机碳的第一个年度估计。人工林二、三级排水口的总有机碳(TOC)通量以溶解有机碳(DOC)为主(91%)，变化范围为34.4+/-9.7 cm-2yr(-1)~57.7%，16.3gcm(2)yr(-1)(+/-95%可信区间)。这些通量是一年一次的调查，受到厄尔尼诺事件的强烈影响，因此观测到的流量比往常要低。通量的大小受到地下水位深度的影响，排水越深的站点TOC通量越高。DOC组分的放射性碳测年表明，所有收集的样品中都存在旧的(1950年代之前)碳，DOC在排水最深的地方的平均年龄为735岁。总体而言，我们的估计表明，河流中的TOC占泥炭上油棕榈园碳损失总量的5%左右。维持油棕榈种植园高而稳定的地下水位似乎是将总有机碳损失降至最低的关键。这加强了在热带泥炭地转化研究中考虑所有碳损失途径的重要性，而不仅仅是泥炭表面的二氧化碳排放。
Intact tropical peatlands are dense long-term stores of carbon. However, the future security of these ecosystems is at risk from land conversion and extensive peatland drainage. This can enhance peat oxidation and convert long-term carbon sinks into significant carbon sources. In Southeast Asia, the largest land use on peatland is for oil palm plantation agriculture. Here, we present the first annual estimate of exported fluvial organic carbon in the drainage waters of four peatland oil palm plantation areas in Sarawak, Malaysia. Total organic carbon (TOC) fluxes from the plantation second-and third-order drains were dominated (91 %) by dissolved organic carbon (DOC) and ranged from 34.4 +/- 9.7 Cm-2 yr(-1) to 57.7 %, 16.3 gCm(2) yr(-1) (+/- 95% confidence interval). These fluxes represent a single-year survey which was strongly influenced by an El Nino event and therefore lower discharge than usual was observed. The magnitude of the flux was found to be influenced by water table depth, with higher TOC fluxes observed from more deeply drained sites. Radiocarbon dating on the DOC component indicated the presence of old (pre-1950s) carbon in all samples collected, with DOC at the most deeply drained site having a mean age of 735 years. Overall, our estimates suggest fluvial TOC contributes similar to 5% of total carbon losses from oil palm plantations on peat. Maintenance of high and stable water tables in oil palm plantations appears to be key to minimising TOC losses. This reinforces the importance of considering all carbon loss pathways, rather than just CO2 emissions from the peat surface, in studies of tropical peatland land conversion.