贵州高原草海湿地土壤有机碳分布特征及其与酶活性的关系

基于时空替代的研究方法,对贵州草海湿地土壤有机碳和氧化还原酶活性分布进行了研究,分析了土壤总有机碳(TOC)和可溶性有机碳(DOC)与土壤酶活性、环境因子之间的关系.结果表明,不同退化梯度湿地土壤中有机碳存在较大的差异,沿着退化梯度表层土壤TOC、DOC含量和脱氢酶(DHA)活性逐渐降低(p0.05),而多酚酶(PPO)活性逐渐升高(p0.05);在垂直剖面上,原生湿地(CH1)和轻度退化湿地(CH_2)土壤TOC先增加后减少,而沼泽化湿地(CH3)和草甸湿地(CH_4)土壤TOC无明显的分层和富聚现象;相关性分析表明,TOC、DOC与PPO显著负相关(p0.01),而PPO与土壤含水率(WHC)、总氮(TN)和硝酸盐(NO-3-N)含量等显著负相关(p0.01),与pH显著正相关(p0.01).以上结果表明,土壤有机碳和酶活性的变化是对湿地退化的响应,湿地退化碳库的损失与PPO活性增加有关,而WHC、TN、NO-3-N和pH是影响PPO活性分布的重要因子.

Distribution characteristics of soil organic carbon and its relationship with enzyme activity in the Caohai wetland of the Guizhou Plateau

In this study, we determined the distribution characteristics of soil organic carbon and oxidoreductases activity in the Caohai wetland of Guizhou Plateau, and investigated the relationships between total organic carbon(TOC), dissolved organic carbon(DOC), polyphenol oxidase(PPO), dehydrogenase(DHA) and environmental factors. The results showed that there was significant difference in the wetland soil TOC content at different degradation stages.Soil TOC,DOC and DHA decreased significantly(p<0.05)and PPO increased significantly(p<0.05)along the wetland degradation stages. Soil TOC content in native and mild-degraded wetlands(CH1 and CH2) decreased with depth in the top soil and increased subsequently in the deep soil,however, that of swamp and meadow wetlands(CH3 and CH4) did not show clear vertical stratification and accumulation phenomenon. There were significant negative correlations between wetland soil TOC, DOC and PPO (p<0.01). Significant negative correlations existed between PPO and soil water content (WHC), total nitrogen (TN) as well as nitrate (NO₃^--N) (p<0.01), whereas significant positive correlations existed between PPO and soil pH (p<0.01). These results suggested that the changes of soil organic carbon and enzyme activity responded to the degradation of wetlands, and loss of carbon stocks along with wetland degradation could probably be linked to was primarily due to the increase of PPO activity, and the WHC, TN, NO₃^--N and pH were the important driving factors for PPO activity.