Abstract: To study influence of sand burial depths on the sprouting and growth of Cynodon dactylon in low-water-levelfluctuating zone of the Three Gorges Reservoir after flooding, C. dactylon was transplanted and buried by 10 cm and 20 cm depth sands, respectively. Results showed that 10cmdepth sand burial significantly inhibited the sprouting of C. dactylon, and its sprouting rate was reduced by 15.5%. On the contrary, 20cmdepth sand burial increased the sprouting rate by 75.9%. During the experiment, sprouted seedlings of 10cmdepth sand burial could penetrate the cover layer of the sands and formed ramets, but the seedlings of 20cmdepth sand burial couldn’t. For the former, stem length, stem width, internode number, total internode number, ratio of internode number to stem length, leaf length, leaf number, fresh weight, dry weight, ratio of dry weight to fresh weight were 19.2%, 8.2%, 45.4%, 16.8%, 42.7%, 7.2%, 4.0%, 19.1%, 35.3%, and 13.5% higher than those of the control, respectively. However, for the latter, stem length, internode number, fresh weight, dry weight, ratio of dry weight to fresh weight were 76.3%, 20.3%, 88.3%, 92.6%, and 36.7% lower than those of the control, respectively. Furthermore, under the 10cmdepth sand burial, total stem length of seedlings, total leaf number of seedlings, total fresh weight of seedlings, total dry weight of seedlings, ratio of total fresh weight of seedlings to total population fresh weight, ratio of total dry weight of seedlings to total population dry weight were 4.2%, 36.3%, 31.9%, 22.7%, 24.4%, and 12.4% lower than under the control, respectively. Under the 20cmdepth sand burial, total stem length, total fresh weight of seedlings, total dry weight of seedlings, ratio of total fresh weight of seedlings to total population fresh weight, ratio of total dry weight of seedlings to total population dry weight were 65.3%, 74.5%, 83.8%, 76.4%, and 86.7% lower than under the control, respectively. These results indicated that 10cmdepth sand burial could promote the elongation of stems and leaves and the formation of internodes and leaves of C. dactylon, reducing sand burial’s injury. However, 20cmdepth sand burial couldn’t make seedlings grow normally.

Key words: community structure, secondary Picea forest, spatial pattern, species composition