基于景观尺度下的鄱阳湖湿地浅层土有机碳的空间特征

湿地土壤有机碳研究是全球碳循环研究的基础性工作, 对于准确评估湿地固碳增汇和全球温室气体减排都具有重要意义。以鄱阳湖国家自然保护区为研究区域, 选择六种景观类型(湿地洲滩景观包括受人工控制的碟形湖泊常湖池、半人工控制的碟形湖泊蚌湖、不受人工控制的洲滩前缘泗洲头以及岗地景观包括林地、田地和菜地), 湿地洲滩景观在各1 m高程(泗洲头和蚌湖采样高程10-17 m, 常湖池采样高程12-17 m)内的浅土壤采取3个土壤样品, 岗地景观浅层土壤各采取3个土壤样品, 分析浅层土壤有机碳含量。结果表明, 鄱阳湖不同景观类型的浅层土壤有机碳含量差异性显著。湿地洲滩浅层土壤(特别是0-10 cm土层)的有机碳随高程梯度变化呈现倒U型变化, 即低海拔与高海拔土壤有机碳的含量较中海拔土壤有机碳的含量低, 泗洲头洲滩土层0-10 cm的有机碳含量最高值出现在13-14 m高程, 其中0-10 cm土层的土壤有机碳含量变化值为1.56-12.29 g·kg-1, 10-20 cm土层的土壤有机碳含量变化值为0.96-8.19 g·kg-1; 蚌湖洲滩土层0-10 cm的有机碳含量最高值出现在14-15 m高程, 其中0-10 cm土层的土壤有机碳含量变化值为6.36-23.32 g·kg-1, 10-20 cm土层的土壤有机碳含量变化值为4.14-8.88 g·kg-1; 常湖池洲滩土层0-10 cm的有机碳含量最高值出现在16-17 m高程, 其中0-10 cm土层的土壤有机碳含量变化值为6.51-18.91 g·kg-1, 10-20 cm土层的土壤有机碳含量变化值为3.83-10.05 g·kg-1。岗地浅层土壤有机碳(特别是0-10 cm土层)田地的土壤有机碳含量最高, 菜地土壤有机碳含量最低。比较六种景观类型的浅层土壤有机碳含量, 泗洲头洲滩浅层土壤有机碳含量最低, 蚌湖洲滩浅层土壤有机碳含量最高。六种景观类型的浅层土壤有机碳含量呈现一致的现象是土层0-10 cm的机碳含量明显高于土层10-20 cm的有机碳含量, 说明鄱阳湖国家自然保护区内土壤有机碳含量主要富集在土壤浅层的特征。土壤pH值对湿地土壤有机碳呈显著负相关性, 而土壤含水量、地上部分生物量与土壤有机碳呈显著正相关性。

Spatial characteristic of SOC in surface soil in different landscape of Poyang Lake wetlands

Research of soil organic carbon(SOC)was the foundation for global carbon cycle,and it payed an important role to accurately evaluate the carbon sink and greenhouse gases reduction.The national reserve of Poyang Lake was an example to analyze the SOC in surface soil with a depth 0-20 cm to be sampled from six different landscapes.The marshland was sampled in three plots in each elevation,and the woodland,vegetable land and rice land was sampled in three plots.The elevation of Sizhoutou marshland and Banghu marshland were from 10 m to 17 m elevation,and the elevation of Changhuchi marshland was from 12 m to 17 m.The result explained the SOC in surface soil was different in six landscapes.The SOC in surface soil in marshland was various when the elevation changed(especially the depth of soil in 0-10 cm),and it was the reversed U in the figure.Namely,the content of SOC was low in lowest elevation and highest elevation,however,it was high in middle elevation.The high content of SOC was in 13-14 m elevation in Sizhoutou marshland,the range was 1.56-12.29 g·kg^-1 in the depth 0-10 cm,and the range was 0.96-8.19 g·kg^-1 in the depth 10-20 cm.The high content of SOC was in 14-15 m elevation in Banghu marshland,the range was 6.36-23.32 g·kg^-1 in the depth 0-10 cm,and the range was 4.14-8.88 g·kg^-1 in the depth 10-20 cm.The high content of SOC was in 16-17 m elevation in Changhuchi marshland,the range was 6.51-18.91 g·kg^-1 in the depth 0-10cm,and the range was 3.83-10.05 g·kg^-1 in the depth 10-20 cm.The content of SOC was high in rice land,and the content of SOC was low in vegetable land in others three landscapes.The highest content of SOC was in Banghu marshland,and the lowest content of SOC was in Sizhoutou marshland in six landscapes.They were the same characteristic of SOC,the content of SOC was higher in depth 0-10 cm than in depth 10-20 cm,and it explained the SOC was accumulation in surface soil in National Reserve of Poyang Lake.The pH was negatively correlated with soil organic carbon,while soil water content,aboveground biomass and soil organic carbon were positively correlated.