Abstract: The distribution characteristics of the soil organic matter,total nitrogen,and total phosphorus contents at 5 soil profiles with the different distances from the water surface,and the different groundwater level,were studied by the method of the space for time substitution in the degraded wetland of Mu Us Sandy land.The results show that the soil organic matter and total nitrogen had one enrichment layer,i.e.peat settled layers before the wetland degraded and the depth of the peat layer gradually increased along with the aggravation of wetland degradation degree.The content of soil organic matter and total nitrogen above the enrichment layer tend to be identical.The soil phosphorus had a larger fluctuation cross the profile and the distribution characteristic had no significant correlation with the wetland degradation.All these results show that the invasion of mobile dune could be the first cause of wetland degradation.

Key words: Mu Us sandy land, Degraded wetland, Soil nutrients, Response

摘要： 采用湿地生态理论中空间替代时间的研究方法,以毛乌素沙区退化湿地为研究对象,选择距退化湿地水面不同距离,具有不同地下水位埋深的研究区域代表湿地不同退化阶段,通过分析5个不同阶段退化湿地土壤的有机质、全氮、全磷随水平距离的变化特征,研究了土壤养分对湿地退化不同退化程度的响应特征。结果表明,不同退化阶段土壤有机质与全氮剖面均具有一个明显的富集层,既湿地退化前的泥炭沉积层。该沉积层在剖面中所处深度随退化程度的加剧而逐渐增加,且沉积层以上深度的有机质和全氮含量趋于一致。土壤中全磷含量在剖面波动较大,分布特征无明显规律,不同水平距离全磷平均含量无明显变化规律说明湿地退化对全磷含量无明显影响。以上研究结果表明,由于流动沙丘入侵是导致毛乌素沙地湿地退化的首要原因,湿地退化导致土壤有机质和全氮富集层深度逐渐下移,平均含量逐渐下降,而对全磷影响不大。

关键词: 毛乌素沙区, 退化湿地, 土壤养分, 响应