鄱阳湖典型湿地土壤有机碳分布及影响因子

在南矶湿地国家级自然保护区设置采样带,对鄱阳湖典型湿地土壤有机碳分布及影响因子进行了研究。结果表明:1)湿地土壤0～15、15～30、30～50cm有机碳含量分别为1.07%～3.52%、0.31%～1.96%、0.27%～0.92%,有机碳含量自表层以下急剧降低。2)湿地土壤0～50cm有机碳密度变化范围为3.02～10.19kg·m-2,其中,表层0～15cm约占42.5%～72.6%;土壤有机碳含量、碳密度均以苔草植物群落最高,其他依次为南荻群落、南荻+苔草群落、芦苇群落、水蓼群落。3)土壤水分与植物生物量是鄱阳湖湿地土壤有机碳分布的2个主要影响因子,土壤水分能解释湿地表层0～15cm有机碳40%的变异,总生物量则能解释28%的土壤有机碳变异。4)鄱阳湖湿地碳密度与长江中下游地区的湖泊湿地类型具有较好的可比性,远低于若尔盖、三江平原等冷区泥炭湿地类型。

Distribution pattern of soil organic carbon in Poyang Lake wetland and related affecting factors

In order to provide basic data for further study the wetland carbon cycle in Poyang Lake and to understand the responses of soil organic carbon pool to climate change, sampling belts were installed in Nanji Wetland National Nature Reserve, and soil organic carbon content was analyzed. In the Reserve, the soil organic carbon content in 0-15, 15-30, and 30-50 cm layers was 1.07%-3.52%, 0.31%-1.96%, and 0.27%-0.92%, respectively, being decreased sharply from top to deep layers. The soil carbon density in 0-50 cm depth ranged in 3.02-10.19 kg·m-2, and that in 0-15 cm layer accounted for 42.5%-72.6% of total carbon stock. Both the soil organic carbon content and the carbon density were the highest under Carex cinerascens-dominated community. Soil moisture and plant biomass were the two main factors affecting the distribution of soil organic carbon and carbon density. Soil moisture explained 40% of the top layer organic carbon variation, while total plant biomass explained 28% of the variation. By comparison, the soil carbon density in Poyang Lake wetland was closer to that in other lake wetlands in the middle and lower reaches of Yangzi River, but far lower than that in the peat lands in Ruoergai Plateau and Sanjiang Plain.