Abstract: The seasonal variation of calorific power of the litters of three typical wetland plants decomposing through one growth season were studied and its influencing factors were explored.The calorific power of the litters varied from plant community to community due to differences in their micro-environment.In the Calamag rostis angustifolia community,the calorific power tended to decline gradually from June to October,whereas in the Carex lasiocarpa community and Carex pseudocuraica community,it showed a dropped-rose-dropped trend,owing to their positions in the annular wetland leading to hydrothermic conditions different from the former′s.The calorific power also varied with depth of the litter layer in the same community.It showed a similar trend in the depth of 0-10,10-20,2030 cm,but a significantly different one in the depth of 3040 cm.

Key words: annular wetland, litter, calorific power, Calamag rostis angustifolia, Carex lasiocarpa, Carex pseudocuraica