Abstract: The study of retrogress grassland species structure and diversity under the wasteland and Caragana forest with different density recover measures in Mu Us sandy land showed that the planting Caragana forest played a positive role in vegetation restoration.Along with the span of Caragana rows increasing,community structure tended to be more stable.Community structure succeeded from the instable annual of species of C.tylocarpum and Salsola collina in the wasteland to stable perennial species dominated by Pennisetum centrasiaticum,Leymus secalinus and Astragalus melilttoides.Vegetation coverage was in order of 10 m>7 m >4 m in terms of span width,while that of the community diversity was 10 m>4 m >7 m.There was positive correlation between the community evenness index and diversity index,while negative correlation between the dominate index and diversity index.

Key words: Daphnia magna, 1,8-dihydroxyanthraquinone, Toxicity, Toxicology