Wong Guan Xhuan, Hirata Ryuichi, Hirano Takashi, Kiew Frankie, Waili Joseph Wenceslaus, Mander Ülo, Soosaar Kaido, Melling Lulie
Sarawak Tropical Peat Research Institute, Kota Samarahan, Malaysia.
Center for Global Environmental Research, National Institute for Environmental Studies, Tsukuba, Japan.
Sci Total Environ. 2025 Jan 25;962:178466. doi: 10.1016/j.scitotenv.2025.178466. Epub 2025 Jan 14.
Tropical peatlands are significant sources of methane (CH₄), but their contribution to the global CH₄ budget remains poorly quantified due to the lack of long-term, continuous and high-frequency flux measurements. To address this gap, we measured net ecosystem CH exchange (NEE-CH) using eddy covariance technique throughout the conversion of a tropical peat swamp forest to an oil palm plantation. This encompassed the periods before, during and after conversion periods from 2014 to 2020, during which substantial environmental shifts were observed. Draining the peatland substantially lowered mean monthly groundwater levels from -20.0 ± 14.2 cm before conversion to -102.3 ± 31.6 cm during conversion and increased slightly to -96.5 ± 19.3 cm after conversion. Forest removal increased mean monthly soil temperature by 2.3 to 3.1 °C, reducing net radiation (R) and raising vapor pressure deficit (VPD). Following the tree removal, controlled burning temporarily warmed air temperature by 8 °C, increased VPD and significantly attenuated R, resulting in negative values owing to radiation interception by smoke and increased surface warming. Contrary to expectations that drainage would lower CH emissions, the site remained a consistent net source, with even higher emissions observed during and after conversion. The mean monthly NEE-CH during conversion (23.3 ± 8.6 mg C m d) was about 2-times higher than before conversion (12.1 ± 5.3 mg C m d) and about 1.5-times higher than after conversion (16.3 ± 4.1 mg C m d). The heightened CH release is likely attributable to emissions from drainage ditches, underscoring their significant role in post-conversion CH dynamics. Despite its short duration, controlled burning substantially elevated NEE-CH, ranging from 0.04 to 0.91 mg C m s. Our findings highlight the substantial impact of land conversion on peatland CH dynamics, emphasizing the need for accurate flux measurements across various conversion stages to refine global CH budgets.
热带泥炭地是甲烷（CH₄）的重要来源，但由于缺乏长期、连续和高频的通量测量，它们对全球CH₄预算的贡献仍未得到很好的量化。为了填补这一空白，我们在一个热带泥炭沼泽森林转变为油棕种植园的整个过程中，使用涡度协方差技术测量了生态系统净CH交换（NEE-CH）。这涵盖了2014年至2020年转变期之前、期间和之后的时间段，在此期间观察到了显著的环境变化。排干泥炭地使平均每月地下水位大幅下降，从转变前的-20.0±14.2厘米降至转变期间的-102.3±31.6厘米，并在转变后略有上升至-96.5±19.3厘米。森林砍伐使平均每月土壤温度升高了2.3至3.1°C，减少了净辐射（R）并提高了水汽压差（VPD）。树木砍伐后，控制性焚烧使气温暂时升高了8°C，增加了VPD并显著减弱了R，由于烟雾对辐射的拦截和地表变暖加剧，导致R出现负值。与排水会降低CH排放的预期相反，该地点仍然是一个持续的净源，在转变期间和之后观察到了更高的排放。转变期间的平均每月NEE-CH（23.3±8.6毫克碳/平方米/天）比转变前（12.1±5.3毫克碳/平方米/天）高出约2倍，比转变后（16.3±4.1毫克碳/平方米/天）高出约1.5倍。CH释放的增加可能归因于排水沟的排放，突出了它们在转变后CH动态中的重要作用。尽管控制性焚烧持续时间较短，但它显著提高了NEE-CH，范围从0.04至0.91毫克碳/平方米/秒。我们的研究结果突出了土地转变对泥炭地CH动态的重大影响，强调需要在各个转变阶段进行准确的通量测量，以完善全球CH预算。
