采用凋落袋法，研究了亚热带低洼滩地绿化树种湿地松(Pinus elliottii Engelm.)、‘中山杉302’(Taxodium ‘Zhongshanshan 302’)、垂柳(Salix babylonica Linn.)和乌桕〔Triadica sebifera (Linn.) Small〕凋落叶在3种水位〔水位位于土壤界面之上5 cm(Tf)、水位与土壤界面持平(Tw)及水位位于土壤界面之下5 cm(Td)〕下180 d内的分解规律，分析了不同凋落叶分解对土壤有机碳组分和微生物群落结构的影响。结果表明：凋落叶种类和水位显著(P＜0.05)或极显著(P＜0.01)影响凋落叶分解及土壤有机碳含量。凋落叶C/N比和纤维素含量越低，其分解速率越快。垂柳和乌桕凋落叶分解较快，湿地松凋落叶分解最慢，‘中山杉302’凋落叶分解居中。Tf、Tw和Td处理中，凋落叶分解180 d时乌桕凋落叶干质量损失率均最高，分别为94.14%、69.80%和79.67%，对应土壤有机碳含量也最高，分别为11.99、11.97和12.38 g·kg^-1。相关性分析结果表明：土壤有机碳含量与土壤M/P比（土壤矿物结合态有机碳含量与颗粒态有机碳含量的比值）呈极显著负相关。此外，水位对土壤微生物群落影响较大，Td处理中纤维素、木质素分解性细菌和真菌富集，而Tw和Tf处理中厌氧细菌及水生真菌的相对丰度较大。综上所述，乌桕凋落叶分解较快，其通过短期内输入大量不稳定碳组分增加土壤有机碳含量；与凋落叶种类相比，水位对土壤微生物群落结构的塑造更为明显。

The decomposition patterns within 180 d of leaf litter from wetland greening tree species in subtropics, namely Pinus elliottii Engelm., Taxodium ‘Zhongshanshan 302’, Salix babylonica Linn., and Triadica sebifera (Linn.) Small, at three water levels 〔water level is 5 cm above the soil interface (Tf), water level is at the same level with the soil interface (Tw), and water level is 5 cm below the soil interface (Td)〕 were investigated by using the litterbag method, and the effects of decomposition of different leaf litter on soil organic carbon composition and microbial community structure were analyzed. The results show that leaf litter species and water level significantly (P<0.05) or extremely significantly (P<0.01) affect leaf litter decomposition and soil organic carbon content. Leaf litter with lower C/N ratio and cellulose content has faster decomposition rate. The decomposition of S. babylonica and T. sebifera leaf litter is relatively fast, that of P. elliottii leaf litter is the slowest, and that of T. ‘Zhongshanshan 302’ leaf litter is in the middle. Among Tf, Tw, and Td treatments, the dry mass loss rates of T. sebifera leaf litter are the highest at 180 d of leaf litter decomposition, which are 94.14%, 69.80%, and 79.67%, respectively, and the contents of corresponding soil organic carbon are also the highest, which are 11.99, 11.97, and 12.38 g·kg^-1, respectively. The correlation analysis result shows that soil organic carbon content shows an extremely significant negative correlation with   soil M/P ratio (ratio of soil mineral-bound organic carbon content to particulate organic carbon content). In addition, water level has a relatively large impact on soil microbial community, cellulose-and lignin-degrading bacteria and fungi are enriched in Td treatment, while the relative abundance of anaerobic bacteria and aquatic fungi is relatively large in Tw and Tf treatments. In conclusion, T. sebifera leaf litter decomposes relatively fast, which increases soil organic carbon content by inputting a large amount of unstable carbon components in a short term; compared with leaf litter species, water level exerts more evident effects in shaping soil microbial community structure.