盐度对互花米草枯落物分解释放硅、碳、氮元素的影响

为了研究潮汐湿地盐度对枯落物分解过程中硅、碳、氮元素释放的影响,通过室内模拟不同盐度(0、5、15和30)对互花米草枯落物茎和叶分解释放过程中硅、碳、氮元素的动态变化进行测定。结果表明:(1)互花米草茎和叶枯落物失重率和分解速率均随盐度增加而降低。(2)互花米草茎和叶枯落物分解水体中硅含量均随着盐度升高而增加,并且盐度30处理下,枯落物分解硅释放量显著高于盐度0和5(P0.05)。而分解末期生物硅残留量则随盐度升高而降低。(3)不同盐度处理茎枯落物分解碳释放量无显著差异,但叶枯落物分解碳释放量在盐度5、15和30处理中显著高于淡水(P0.05)。(4)互花米草茎枯落物分解释放到水中的NH_4~+-N含量随着盐度的升高而减少,NO_3~--N含量与之相反。研究单因素盐度对枯落物分解及元素释放的影响,可以为预测潮汐湿地枯落物分解对盐水入侵的响应机制提供参考,为湿地生源要素生物地球化学循环过程研究提供基础依据。

Effect of salinity on silicon, carbon, and nitrogen during decomposition of Spartina alterniflora litter

To investigate the effect of salinity on silicon, carbon, and nitrogen values during decomposition of wetland litter, the changing dynamics of silicon, carbon, and nitrogen in Spartina alterniflora stems and leaves under different salinities (0, 5, 15, and 30) were analyzed in the laboratory. The results showed that the percentage weight loss and decomposition rate of litter decreased with increasing salinity. The silicon release concentrations of litter increased with higher salinity, and were significantly greater in the high salinity treatment (30) than in the freshwater(0) and low salinity(5) treatments (P < 0.05). In contrast, the biogenic silica (BSi) residual contents demonstrated an opposite trend during the terminal decomposition. The carbon contents released from the stem were not significantly different between the different salinity treatments, but the leaf were lower in the freshwater treatment than in the other treatments (P < 0.05). In the higher salinity treatments, the stem litter had higher NH₄⁺-N release, with NO₃^--N contents shown to be the opposite. Salinity impact studies on litter decomposition and element release provides reference information for decomposition responses of tidal wetland litter to saltwater intrusion and is the basis for further research on biogeochemical cycles of biogenic elements in wetlands.