中文摘要：

在鄱阳湖南矶湿地国家级自然保护区沿水位梯度采集了7种优势植物群落下0～15、15～30 cm土壤样品，测定了土壤总有机碳（SOC）、重组有机碳（HFOC）、轻组有机碳（LFOC）、微生物生物量碳（MBC）和可溶性碳（DOC）含量，以阐明鄱阳湖典型湿地土壤有机碳及其不同组分特征与影响因子，探讨植物群落演替对有机碳库及其组分的影响。结果表明：（1） 各群落0～30 cm土层SOC、HFOC、LFOC、MBC和DOC含量变化范围分别为4.92～48.14 mg·g-1、4.66～41.42 mg·g-1、0.46～6.52 mg·g-1、124.22～419.23 mg·kg-1和33.17～153.63 mg·kg-1。（2） 土层、群落类型及其交互作用均对总有机碳及其组分产生显著影响，水位梯度的影响未达到显著性。（3） 湿地0～30 cm土壤HFOC、LFOC、MBC和DOC占总有机碳平均比例分别为92.9%、7.1%、1.44%和0.74%，土壤碳库以稳定的重组有机碳为主，LFOC、MBC、DOC等3种活性有机碳组分在空间分布上没有表现出一致性。（4） 鄱阳湖湿地沉水植物群落退缩，湿生、挺水植物群落的扩展短期内将增加土壤碳储量，但碳库的稳定性降低。

英文摘要：

Soil organic carbon is composed of active, slow and passive fractions. Separating different organic carbon components could help to improve modeling dynamic of soil organic carbon pool and its feedback to global climate change. Poyang Lake is the largest freshwater lake in China. It is a typical subtropical shallow water lake characterized by drastic annual and inter-annual water level fluctuation. In recent years, climate change and the operation of the Three Gorges Dam have largely altered the hydrological regime of Poyang Lake, resulting in reduction of summer flooding and extension of winter dry season. As a result, the submerged plant communities shrank, whereas the emergent plant communities expanded. In this study, soil samples at 0-15 cm and 15-30 cm depths under seven dominant plant communities were collected along a water table gradient in a typical Poyang Lake wetland. Subsequently, contents of total soil organic carbon （SOC）, heavy fraction organic carbon （HFOC）, light fraction organic carbon （LFOC）, microbial biomass carbon （MBC） and dissolved organic carbon （DOC） were measured. The objectives of this study were to clarify the characteristics of various soil organic carbon components and their affecting factors, and explore the potential impact of community succession on soil organic carbon and its components. Our results showed that the ranges of SOC, HFOC, LFOC, MBC and DOC were 4.92-48.14 mg·g-1, 4.66-41.42 mg·g-1, 0.46-6.52 mg·g-1, 124.22-419.23 mg·kg-1 and 33.17-153.63 mg·kg-1, respectively. The organic carbon components varied significantly with plant communities and soil layers. The content of each soil organic carbon component under various plant communities decreased from the top soil to the deeper profile. Soil layers and communities types as well as their interaction all significantly affected the spatial pattern of various organic carbon components. The ratios of HFOC/SOC, LFOC/SOC, MBC/SOC and DOC/SOC were 92.9%, 7.1%, 1.44% and 0.74%, respectively. The distrib