科尔沁沙地围封草地种子库特征

科尔沁沙地自由放牧草地围封7a后土壤种子库中植物种类有25种，其中一、二年生植物19种，土壤种子库密度3314粒.m^-2，其中，黄蒿（Artemisia scoparia)、狗尾草（Setaria viridis)、三芒草（Aristida adscensinis)等一年生植物种子占总数的95.3%，而多年生植物仅占4.7%。若以单子叶和双子叶植物统计，单子叶植物种子数占14%，双子叶植物的种子数占86%，其中豆科植物仅占2.4%。土壤种子库植物的种子数与其相应植物在植被中出现频率有明显的相关性，从种子库组成分析，围封7a的草地植被维持在黄蒿一杂类草混合植被阶段，围封草地对农牧生产方式转换频繁的科尔沁沙地草地植被恢复起着“种子岛”作用，它们的存在可以缩短周围被干扰草地恢复的时间，应该加强围封草地的管理利用研究。

Characteristics of Seed Bank at Fenced Grassland in Horqin Sandy Land

The seed bank of sandy grassland after 7 years enclosure (nograzing) was investigated. The results showed that ①the number of plant species was 25, and that of annuals and biennals was 19 in the seed bank; ②The density of seed bank was 3 314 grains.m-2, and 95.3% of that was seeds of Artemisia scoparia, Setaria viridis and Aristida adscensinis and other annuals, whilst 4.7% of that was those of perennials; ③If divided into monotyledoneous and dicotyledonueous, the number of seeds of former accounted for 14% of that of total seeds while that of later constituted 86%,and that of bean family species comprised 2.4%; ④There exists a significant correspondence between the number of seed bank and the frequency of associated vegetation;⑤The fenced grassland vegetation will be in the stage of mixture of Artemisia scoparia and forbs; ⑥Fenced grasslands provided their surrounding disturbed grassland a seed island. This can reduce the restoration processes of these disturbed habitats effectively. Therefore, the relevant researches on the management and utilization of fenced grasslands should be paid more attention to.