| 独流减河不同植被缓冲带土壤有机碳的空间分布特征及其季节变化 |
| 摘要点击 1591 全文点击 417 投稿时间：2023-12-21 修订日期：2024-02-23 |
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| 中文关键词 独流减河 植被缓冲带 土壤有机碳（SOC） 溶解性有机质（DOM） 季节变化 |
| 英文关键词 Duliujian River vegetation buffer zone soil organic carbon（SOC） dissolved organic matter（DOM） seasonal variation |
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| 中文摘要 |
| 不同植被类型会影响土壤有机碳（SOC）的积累和转移特征,但这种影响是否通过枯落物的输入或根系调节土壤环境因子以及溶解性有机质（DOM）以达到有机碳固定的目的尚不清晰.以天津市独流减河生态堤岸上部的乔木林带、中部的混交林带和滨水植物带的土壤为研究对象,研究不同植被带表层土壤（0~10 cm）中易氧化有机碳（EOC）、溶解性有机碳（DOC）、颗粒有机碳（POC）和矿物质结合态有机碳（MAOC）的空间分布特征及其季节变化,并结合紫外可见光谱和三维荧光光谱进一步分析土壤DOM组分及其介导作用. 结果表明：①夏季滨水植物带SOC的积累显著高于乔木林带和混交林带,春季则正好相反,这表明夏季土壤中根系的分布是决定SOC积累的关键因素,而春季地上枯落物的输入质量对SOC的固存更重要. ②DOM组分的差异解释了SOC在不同季节的固定和转化方式,春季类腐殖质DOM促进了DOC向POC和MAOC的转化,而夏季微生物来源的DOM推进了EOC在微生物的作用下向MAOC转移的过程. ③土壤理化性质对SOC的直接影响较小,其更倾向于通过调控土壤DOM的成分以及化学结构,从而影响SOC的积累. ④结构方程模型表明含水率（MC）和总磷（TP）直接参与了土壤有机碳的迁移和转化过程,而铵态氮（NH4+-N）、硝态氮（NO3--N）、电导率（EC）、有效磷（AP）、pH、K+和Na+则是通过腐殖质来源和微生物来源的DOM介导间接影响SOC积累. 综上所述,本研究阐释了影响河岸水陆生态交错带这一关键功能区SOC封存的权衡机制,研究结果可为进一步探索入海河流“流域-河口-近海”系统生态廊道的构建方法及其固碳增汇路径提供理论支持. |
| 英文摘要 |
| Different vegetation types may affect the accumulation and transformation of soil organic carbon （SOC）, but it is unclear whether the organic carbon fixation is realized by litter input and/or root control of environmental factors and dissolved organic matter （DOM） of soils. In this study, the spatial distribution characteristics of easily oxidizable organic carbon （EOC）, dissolved organic carbon （DOC）, particulate organic carbon （POC）, mineral-bound organic carbon （MAOC）, and their seasonal variations in the surface soil （0-10 cm） were studied in different vegetation zones of the arbor forest （at the upper position）, the mixed forest of arbor and shrub （at the middle position）, and the waterfront vegetation （at the bottom position） in the ecological embankment of Duliujian River, Tianjin, China. The spatial distribution characteristics of soil DOM components and their seasonal changes were also analyzed by combining UV-visible spectroscopy and 3D fluorescence spectroscopy. The results showed that： ① The accumulation of SOC was significantly higher in the waterfront vegetation than in the arbor forest and the mixed forest of arbor and shrub in summer, whereas the opposite was true during the spring season. It was indicated that the root input of the soil was the key driving factor for determining the accumulation of SOC in summer, whereas the input quality of above-ground litters was more important for the sequestration of SOC in spring. ② Differences in DOM fractions explained the fixation and transformation pathways of SOC in different seasons, with humus-derived DOM in spring promoting the transformation of DOC to POC and MAOC and microbial-derived DOM in summer advancing the transfer of EOC to MAOC under the action of microorganisms. ③ Soil physicochemical properties had less direct influences on SOC, which preferentially affected SOC accumulation by regulating the composition as well as the chemical structure of soil DOM. ④ The structural equation modeling indicated that water content （MC） and total phosphorus （TP） were directly involved in SOC transport and transformation, whereas ammonium nitrogen （NH4+-N）, nitrate nitrogen （NO3--N）, electrical conductivity （EC）, available phosphorus （AP）, pH, K+, and Na+ indirectly affected SOC accumulation mediated by DOM from humus and microbial sources. In summary, the present study elucidated that the trade-off mechanisms affecting SOC sequestration in the critical functional zone along the land-river ecotone, and the results can provide theoretical support for further exploring the constructive methods of ecological corridors and the pathways of carbon sequestration and sink enhancement in the “watershed-estuary-offshore” system of the coastal rivers. |
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