盐城滩涂湿地典型植物群落土壤活性有机碳组分分布特征

Distribution characteristics of active components in soil organic carbon across typical plant communities in Yancheng coastal wetlands

土壤活性有机碳是土壤有机碳动态的敏感性指标,可以及时反映土壤有机碳库的周转和动态变化过程。为探究盐城滩涂湿地土壤活性有机碳组分的分布特征及其影响因素,本研究以江苏盐城滩涂湿地4种典型植物群落为对象,分析了0~10 cm(表层)、10~30cm(中层)、30~60 cm(深层) 3个层次土壤总有机碳(TOC)、易氧化碳(EOC)、水溶性有机碳(DOC)、颗粒有机碳(POC)等与土壤因子、地上生物量等之间的相关性。结果表明:(1)不同植物群落间,土壤TOC含量差异较大,但土壤EOC和DOC含量差异相对较小。不同土层间,互花米草群落深层TOC含量略高,其他群落随深度增加呈下降趋势,POC含量随土壤深度增加逐渐下降。(2)冗余分析表明,地上生物量(AGB)和土壤pH对3个土层土壤有机碳组分含量的单独解释率均为最高,土壤还原性物质总量(RS)的解释率随土壤深度的增加呈上升趋势。土壤含水量(SWC)在表、中层土壤的单独解释率均为最低,其对土壤有机碳组分含量影响较小。(3) EOC在表层土壤中与总磷(TP)、总氮(TN)呈显著正相关,与pH呈显著负相关,在中、深层与土壤因子无显著相关。DOC在表层土壤中与AGB、TP、RS呈显著正相关,在中层土壤中与TN、TP、SWC呈显著正相关,在深层土壤中与pH呈显著负相关。POC在表、中层土壤中与AGB、TP、RS呈显著正相关,在深层中无显著相关性。本研究表明,地上生物量、土壤pH在3个土壤层次对土壤有机碳组分含量的影响均较显著,而土壤氧化还原状况的影响则随土壤深度的增加而更显著。土壤活性有机碳的相对含量及其影响因素,因群落类型、土壤层次、有机碳组分类型等而存在较大差异。

The active components of soil organic carbon are sensitive indicators of carbon stock change,which can timely reflect the turnover and dynamics of soil organic carbon pool. In this study,soil samples at 0-10 cm(surface layer),10-30 cm(middle layer) and 30-60 cm(deep layer) depths of four typical plant communities were collected in Yancheng coastal wetlands. The relationships between soil total organic carbon(TOC),easily oxidizable carbon(EOC),dissolved organic carbon(DOC),particulate organic carbon(POC) and soil environmental factors and aboveground biomass(AGB) were examined. The results showed that:(1)TOC content varied greatly in different plant communities,whereas the differences in soil EOC and DOC contents were relatively minor. TOC content declined with soil depths except for the Spartina alterniflora community,which was slightly higher in deep layers. POC content gradually decreased with soil depths.(2) Redundancy analysis results showed that AGB and soil pH had the highest single explanatory power for the variation of soil organic carbon component content in the three soil layers. With increasing soil depth,the explanatory power of total reducing substances(RS) showed an upward trend. The separate explanatory power of soil water content(SWC) in surface and middle layers was the lowest. Soil water content had little effect on the content of soil organic carbon components.(3) EOC was significantly positively correlated with total phosphorus(TP) and total nitrogen(TN),negatively correlated with pH in surface layer,and had no correlation with soil factors in the middle and deep layers. DOC was significantly positively correlated with AGB,TP,and RS in surface layer,positively correlated with TN,TP and SWC in the middle layer,and negatively correlated with pH in deep layer. POC was significantly positively correlated with AGB,TP and RS in surface and middle layers,but not in the deep layer. Our results indicated that AGB and soil pH significantly affected the contents of soil organic carbon components in the three soil layers,while the effect of soil redox status was more significant with the increasing soil depths. The relative contents of soil organic carbon components and their influencing factors were quite different,depending on community types,soil layers,and organic carbon component types.