The temporal-spatial trends in contents of soil free iron and amorphous iron, and activation degree of iron oxides in soil were studied in three types of wetlands in Momoge National Nature Reserve, including Phragmites marsh and Leymus chineruis meadow and Phragmites-L. chinensii meadow. Result showed that the most significant seasonal variation in the content of soil free iron was in spring, followed by summer and fall. However, the most significant seasonal variation in the content of soil amorphous iron was in summer, followed by fall and spring. Free iron content decreased gradually with increasing soil depth, but there was a slight increase in 60-90 cm. Amorphous iron content decreased from the surface to the deep layer. The content of free iron in L chinensis meadow was the highest, followed by Phragmites marsh and Phrag-mites-L. chineiuis meadow, while the content of amorphous iron was the highest in Phragmites marsh, followed by L. chineruis meadow and Phragmites-L. chinensis meadow. The activation degree of soil iron oxides in wetland in summer and fall was higher than that in spring, and the activation degree decreased from the soil surface to the deep layer.%以莫莫格芦苇沼泽、芦苇—羊草草甸和羊草草甸3种类型湿地土壤为时象,研究了土壤游离铁和无定形铁的质量分数以及铁活化度的时空变化趋势.结果表明:土壤游离铁质量分数的季节变化为春季最明显,其次为夏季,秋季最弱；而无定形铁质量分数的季节变化则表现为夏季明显,秋季次之,春季最弱.随着土壤深度的增加,游离铁质量分数逐渐降低,至60 -90 cm处略有升高；而无定形铁质量分数则表现为自表层向深层递减的规律.3种类型湿地土壤游离铁质量分数比较,羊草草甸最高、芦苇沼泽次之、芦苇—羊草草甸最低；无定形铁质量分数则表现为芦苇沼泽最高、羊草草甸次之、芦苇—羊草草甸最低.湿地土壤铁的活化度夏、秋季节高,春季低；土壤表层铁活化度高于底层.
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