毛乌素沙地飞播植被演替的阶段与速度

毛乌素沙地飞播植物的演替，可分为３个时期或阶段。第１阶段为飞播植物群落阶段；第２阶段为飞播植物＋天然植物或飞播植物＋油蒿群落阶段；第３阶段为天然植物群落阶段或油蒿群落阶段。从各阶段所能维持的时间或演替的速度来看，毛乌素流动沙地飞播以后，飞播植物占优势的阶段最大不超过２０年，飞播植物群落阶段和飞播植物与油蒿共同占优势的时间最大不超过３５年。也就是说，３５年以后，天然植物油蒿在群落中占绝对优势，而飞播植物仅作为伴生种存在。

SUCCESSIONAL STAGE AND RATE OF THE AERIAL SEEDING VEGETATION IN THE MAOWUSU SANDYLAND

Succession of the aerial seeding vegetation in the Maowusu Sandyland can be divided into three periods or stages, the first stage is aerial seeding plants dominated communities stage, the second one is dominated by both aerial seeding plants and natural plant, especially Artemisia ordosica, and the third stage is called natural plants or A. ordosica dominated community stage. With regard to the time of each stage maintained or the rate of succession, the stage dominated by aerial plants is no more than 20 years at most. The period of the first two stages together is less than 35 years, that is to say, 35 years after the aerial seeding A. ordosica will occupy predominance in communities, and the aerial plants will exist only as accompanying species.