不同地下水位灰化薹草分解过程中木质素降解与碳、氮、磷释放的关系

为研究湿地植物分解过程中木质素分解与碳、氮、磷元素释放之间的关系及其对不同地下水位环境梯度的响应,在鄱阳湖典型碟形湖泊-白沙湖设置了200 m×300 m分解试验样地,沿地下水位梯度划分4个试验样带(从湖岸到湖心依次为GT-A, GT-B, GT-C, GT-D),采用分解袋法模拟了典型湿地植物灰化薹草在不同地下水位环境的分解过程。结果表明,分解15 d后,地下水位的升高促进了木质素的分解和碳、氮、磷元素的释放;在分解第60—90天,碳、氮、磷元素的相对归还指数随着木质素分解速率的升高而显著增大,并且相关性程度随着分解时间先增强,后减弱;分解过程中土壤pH、含水量和微生物量碳、氮对木质素的分解和碳、氮、磷元素的归还具有显著的促进作用。研究结果将有助于深化对湿地植物分解和生物地球化学循环过程的认识,为湿地自然保护区的科学有效管理提供理论依据。

Correlations between lignin degradation and the C, N, P release during Carex cinerascens decomposition under different ground water level

To reveal the relationship between lignin degradation and release of Carbon (C), Nitrogen (N), Phosphorus (P) and their response to the change of ground water level, a field experimental site with 200 m×300 m was setup in the beach of Baisha Lake, a typical shallow lake of Poyang Lake Wetlands. The site included 4 ground water levels: GT-A, GT-B, GT-C, and GT-D (moving from shore to center). Litter bag technique was applied to simulate the Carex cinerascens decomposition under different groundwater level gradients. The results showed that the rise of groundwater level promoted the lignin degradation and release of C, N, and P (CRRI, NRRI, PRRI) after 15 days'' decomposition. The CRRI, NRRI, and PRRI had significant positive correlations with lignin decay rates during 60-90 days, and the degree of these correlations increased for the first 60 days and then declined. Lignin degradation and the release of C, N, and P were influenced positively and consistently by soil pH, moisture, soil microbial biomass carbon, and soil microbial biomass nitrogen. This study provides useful insight for plant decomposition and biogeochemical processes of wetland ecosystem, and provides basis for the scientific management of the wetland nature reserves.