Ecological Study Of Algae Crusts In Leymus Chinensis Grassland

In this paper , we studied the algae crusts which is growing in the Leymus chinensis grassland in Jilin Province. In this experiment, we selected six communities :Leymus chinensis,Puccinellia tenuiflora,Chloris virgata, Eleocharis congesta,Carex duriuscula, Alkali spot. First,we identified the species of the algae crusts,and then we studied the allelopathy of the algae crusts which has action on Chloris virgata,s germination percentage and the length of root and bud of Chloris virgata seeds. we also studied the difference of soil water content and soil temperature and nitrogen content between the sample plots with algae crusts and the sample plots without algae crusts. Last we measured the degradation of the algae crusts and the nitrogen content.We also studied the photosynthesis of algae crustsThe results showed that the algae crusts was composed of subaerial blue-green algae. The allelopathy of the algae crusts has no significant affect on Chloris virgata,s germination percentage ,but has significant affact on the length of root and bud of Chloris virgata seeds. Concerning the root ,there has allelopathic inhibition, while about the bud ,the allelopaty of algae crusts in low density can increase the lenth of bud ,and inhibit the length of bud in high density. Soil water content with algae crusts is wetter than that without algae crusts, but only the differences about Alkali spot sample plot were statistically significant. Nitrogen content of sample plots with crusts is higher than that without crusts.Soil temperature with algae crusts is lower than that without algae crusts,and the differences were statisticaly significant except for Alkali spot sample plots and Eleocharis congesta sample plots. The degradation of crusts and nitrogen in crusts is affected by many factors.At last we tried to use LI-6400 photosynthesis equipment and self-made room to measure gas exchange of crusts.