Abstract: We investigatedthe effects of aqueous extract from litter of Spartina alterniflora with different concentrations (0, 0.02, 0.04, 0.10 mg·L^-1) on the growth and physiological characteristics of Skeletonema costatum. The cell concentration of S. costatum, chlorophyll-a content, antioxidant enzyme (superoxide dismutase and peroxidase) activities and malondialdehyde contentwere examined. Moreover, we isolated and identified the algicidal allelochemicals from S. alterniflora. The results showed that the inhibitory effect of the extract of S. alterniflora litter on the growth of S.costatumincreased with the extract concentrations.The inhibitory rate was 69.2% under 0.10 mg·L^-1 of extract. The content of chlorophyll a and the activities of antioxidant enzyme were lower in all treatments than the control, and the content of malondialdehydeincreased in all treatments. The components of allelochemicals from S. alterniflora were mainly composed of long-chain fatty acids, including hexadecanoic acid, linoleic acid, and oleic acid.

Key words: bryophyte soil crust, hydrological process, karst rocky desertification, biological process., physical and chemical properties of soil