洞庭湖不同水位梯度川三蕊柳和短尖薹草土壤有机碳垂直分布特征

Vertical Distribution of Soil Organic Carbon in Salix triandroides and Carex brevicuspis Communities Along Water Level Gradients in the Dongting Lake Wetlands

以洞庭湖湿地3种水位梯度(-60、-40和-20 cm,即水位在土壤表层60、40和20 cm以下)的川三蕊柳(Salix triandroides)和短尖薹草(Carex brevicuspis)为研究对象,揭示0~20、>20~40、>40~60、>60~80 cm土壤有机碳及腐殖质碳(胡敏酸碳、富里酸碳、胡敏素碳)含量的垂直分布特征。结果表明,在3种水位下,川三蕊柳和短尖薹草群落土壤有机碳和腐殖质碳含量均以0~20 cm土壤较高。川三蕊柳0~20 cm土壤有机碳含量以高水位区较高,而>20~80 cm土壤以中水位区较高;短尖薹草4层土壤有机碳含量均以中水位区较高。对土壤富里酸碳含量而言,川三蕊柳和短尖薹草群落在3种水位之间无显著差异。对土壤胡敏酸含量而言,川三蕊柳群落0~20 cm土壤以高水位区较高,>20~60 cm土壤在3种水位之间无显著差异,而>60~80 cm土壤以高水位区较低;短尖薹草群落0~40 cm土壤以中水位区较高,>40~60 cm土壤在3种水位之间无显著差异,而>60~80 cm土壤以高水位区较低。对胡敏素含量而言,川三蕊柳群落0~20 cm土壤以高水位区较高,>20~80 cm土壤以高水位区较低;短尖薹草4层土壤胡敏素碳含量均以中水位区较高。与短尖薹草群落相比,川三蕊柳群落能提高低水位区0~80 cm和高水位区0~20 cm土壤有机碳及腐殖质碳含量,但降低了中水位区0~80 cm和高水位区>20~60 cm土壤有机碳及腐殖质碳含量。可见,湿地土壤有机碳含量受植被类型和水位的综合影响,在洞庭湖湿地应选取高水位洲滩恢复川三蕊柳群落,以提高湿地土壤有机碳含量。

The Salix triandroides and Carex brevicuspis communities in Dongting Lake wetland with three gradient of ground water level were studied, the comparison revealed the content of soil organic carbon and the composition of humus carbon (Humic acid carbon, Fulvic acid carbon and Humin carbon) in the four soil layers (0-20,>20-40,>40-60 and >60-80 cm) of the two plant communities. The results show that:(1) The content of organic carbon and humus carbon in the soil of two species of plant communities was higher at 0-20 cm soil layer.(2) In general, the organic carbon content of the four soil layers in the Carex brevicuspis community was higher in the middle water level area, while in the Salix triandroides community the 0-20 cm soil layer was higher in the high water level area, and the >20-80 cm soil layer was higher in the middle water level. There was no significant difference in the content of fulvic acid carbon between the three water levels in the Salix triandroides community and Carex brevicuspis community. The Salix triandroides community 0-20 cm soil humic acid and humin carbon content in high water level was higher,>60-80 cm soil humic acid carbon content in high water level was low, and >20-40 and >40-60 cm soil layer under the water level of three kinds of humic acid carbon content had no significant difference, in the three-layer of >20-80 cm were all low in high water level. Carex brevicuspis community soil humin carbon content is higher in middle water level area, 0-20 and >20-40 cm soil layer of the carbon content of humic acid in middle water level is higher,>60-80 cm soil layer with high water level is low, 40-60 cm soil layer humin carbon content under the three kinds of water level had no significant difference.(3) In each component of humus, humin carbon content was the highest in both plant communities.(4) Compared with Carex brevicuspis community, Salix triandroides community can improve the low water level area 0-80 cm, and high water area 0-20 cm of soil organic carbon and humus carbon content, but reduces the middle water level in the 0-80 cm, and high water level >20-60 cm soil organic carbon and humus carbon content. So that, the soil carbon of wetland is affected by the comprehensive vegetation type and water level gradient, and it is needed to combine with the hydrological characteristics to scientifically evaluate the soil carbon of wetland.