Root exudate analogues accelerate CO2 and CH4 production in tropical peat
Root exudate analogues accelerate CO2 and CH4 production in tropical peat
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DOI：
10.1016/j.soilbio.2017.11.008
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发表时间：
2018-02-01
影响因子：
9.7
通讯作者：
Sjogersten, S.
中科院分区：
文献类型：
--
作者：
Girkin, N. T.;Turner, B. L.;Sjogersten, S.
在热带泥炭地，根系分泌物是一种大量且不稳定的碳输入，但它们对二氧化碳（CO2）和甲烷（CH4）产生的贡献仍知之甚少。响应全球变化的泥炭地植物群落物种组成和生产力的变化可能改变渗出物的输入和相关的温室气体排放。我们使用可操作的实验室孵育来评估根系分泌物量和化学成分对热带泥炭地温室气体排放的影响程度。在巴拿马的一个疏养湿地中，从冠下棕榈树（Raphia taedigera）和阔叶常绿乔木（Campnosperma panamensis）中取样泥炭。根渗出物类似物由糖和有机酸的混合物组成，被添加到从这两种植物中提取的珍珠的溶液中，随着时间的推移测量CO2和CH4。在大多数处理下，CO2和CH4产量增加，但响应的幅度和持续时间取决于添加的不稳定碳混合物的组成，而不是添加的碳量或泥炭的植物来源。有机酸处理增加了土壤pH值，改变了包括氧化还原电位在内的其他土壤性质，但不影响细胞外水解酶的活性。CO2产量与微生物活性和氧化还原电位呈线性相关，而CH4产量与氧化还原电位呈线性相关。研究结果表明，根系分泌物组成在调节温室气体通量中的重要性，并提出原位植物物种变化，特别是与土地利用变化相关的物种变化，可能解释了物种特异性根系分泌物组成导致的CO2和CH4通量的小尺度空间变化。
Root exudates represent a large and labile carbon input in tropical peatlands, but their contribution to carbon dioxide (CO2) and methane (CH4) production remains poorly understood. Changes in species composition and productivity of peatland plant communities in response to global change could alter both inputs of exudates and associated greenhouse gas emissions. We used manipulative laboratory incubations to assess the extent to which root exudate quantity and chemical composition drives greenhouse gas emissions from tropical peatlands. Peat was sampled from beneath canopy palms (Raphia taedigera) and broadleaved evergreen trees (Campnosperma panamensis) in an ombrotrophic wetland in Panama. Root exudate analogues comprising a mixture of sugars and organic acids were added in solution to peals derived from both species, with CO2 and CH4 measured over time. CO2 and CH4 production increased under most treatments, but the magnitude and duration of the response depended on the composition of the added labile carbon mixture rather than the quantity of carbon added or the botanical origin of the peat. Treatments containing organic acids increased soil pH and altered other soil properties including redox potential but did not affect the activities of extracellular hydrolytic enzymes. CO2 but not CH4 production was found to be linearly related to microbial activity and redox potential. Our findings demonstrate the importance of root exudate composition in regulating greenhouse gas fluxes and propose that in situ plant species changes, particularly those associated with land use change, may account for small scale spatial variation in CO2 and CH4 fluxes due to species specific root exudate compositions.