湿地挺水植物关键指标分解特征研究

Study on Decomposition Characteristics of Key Indexes of Wetland Emergent Aquatic Plant

  • 摘要: 为揭示湿地生态系统中挺水植物凋落物的分解特征,在云南高原湿地选取不同生境下典型广布的水葱和香蒲2种挺水植物,对其生长旺盛期、立枯、倒伏、沉水4个阶段的植物凋落物叶片及水底底泥样品进行采集,测定分析2种植物凋落物的物理、化学(元素及化合物)等关键指标在完整分解周期中的动态变化特征。结果表明:在整个分解期内,2种凋落物的氮、磷、半纤维素和灰分含量变化呈先上升后下降的趋势,表现为“富集–释放”特征;铁含量呈富集上升的趋势,表现为“富集”特征;钾、木质素和纤维素含量则呈释放下降的趋势,表现为“释放”特征。处于沉水阶段的凋落物,其干物质含量、灰分、磷含量、半纤维素含量与前期分解阶段的凋落物之间产生明显的差异性,表明当凋落物接触到水体后其关键指标将发生显著变化,沉水阶段是挺水植物完整分解周期内的重要拐点。在整个分解周期内,2种凋落物的干物质含量、比叶面积、穿刺力度、元素含量(氮、磷、铁、钾)、木质素、纤维素以及半纤维素含量动态变化规律具有趋同性,这些指标的分解动态变化规律可能在不同挺水植物的分解中具有普适性。

     

    Abstract: In order to reveal the decomposition characteristics of the emergent aquatic plants in wetland ecosystems, 2 typical wetland's emergent aquatic plants were selected under different habitats in Yunnan plateau wetlands: Scirpus tabernaemontani and Typha orientalis. The plant leaves litter samples from stages including the growth stage, withered stage, lodging stage, and the submerged stage as well as the bottom sediment samples were collected to analyze the changing dynamics of physical and chemical(elements and compounds) properties of the 2 plant litters in different stages of decomposition. The results showed that the contents of nitrogen, phosphorus, hemicellulose and ash of the 2 litters increased first and then decreased during the whole decomposition period, which was characterized by 'enrichment and release'. The iron content showed a tendency of increasing enrichment, which was characterized by 'enrichment'. The contents of potassium, lignin and cellulose showed a decreasing trend of release, which was characterized by 'release'. The dry matter content, ash content, phosphorus content and hemicellulose content of litters in the submerged stage were significantly different from litters in the early decomposition stage, indicating that the key properties of litters will change significantly after they touch the water body. During the whole decomposition period, the dry matter, specific leaf area, puncture strength, nitrogen, phosphorus, iron, potassium, lignin, cellulose and hemicellulose contents of the 2 litters showed the similar dynamic trends. It is implied that the dynamic change of these properties may be a general pattern involved in the decomposition of emergent aquatic plants.

     

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