Abstract: To study the diurnal dynamics of microclimate at different succession stages of vegetation communities in the inner-river wetland of Zhenjiang City, three typical communities were chosen, and the light intensity, air temperature, soil temperature, and air relative humidity were measured. The results showed that with the succession of barren land →Phalaris arundinacea→Phragmites communis ,the diurnal mean values of light intensity,air temperature, and soil temperature decreased from 1 204.7 μmol·m^-2·s^-1 to 141.28 μmol·m^-2·s^-1, 32.2 ℃ to 24.9 ℃, and 21.83 ℃ to 19.47 ℃, and their daily variations decreased from 1 126 μmol·m^-2·s^-1 to 265 μmol·m^-2·s^-1, 12.75 ℃ to 4.8 ℃, and 4.5 ℃ to 2.1 ℃, respectively. The air relative humidity increased from 58.95% to 87.3%, while its variation decreased from 29.75% to 5.15%. Habitats were open at early succession stage but more closed at late succession stage, microclimatic conditions developed towards much more cloudy, cold, and moist, and microclimate had a less fluctuation. There were definite correlations among the light intensity, air temperature, soil temperature, and air relative humidity in the vegetation communities, but the correlation coefficients among the test factors were differed at different succession stages.

Key words: Hippophae rhamnoides L subsp sinensis, Clonal growth, Ramet group, Structure dynamics, Mu Us sandland