Abstract: Based on the investigation and measurement of Phragmites communis in a single dominant species community in dry land habitat of Songnen Plain, the seasonal variation of dry matter storage and water soluble sugar content in different age classes rhizomes at three growth stages were analyzed. The results showed that at all growth stages, younger age class rhizomes had lower dry matter storage and water soluble sugar content, and there was an obvious difference between younger and older age classes. The dry matter storage and water soluble sugar content in younger age class rhizomes increased rapidly with growth season, and the difference between younger and older age classes reduced gradually. In the whole growth season, all the rhizomes of six age classes kept up the activities in nutrient consumption, restorage and even overcompensating storage, and the activities of younger age class rhizomes were much higher. The dry matter storage and water soluble sugar content in older age class rhizomes increased with year. There existed extremely significant differences (P<0.01) in the dry matter storage within and among different age class rhizomes, and the difference was larger within age classes than among age classes. Significant differences (P<0.05) in water soluble sugar content were also observed among different age class rhizomes. The dry matter storage and water soluble sugar content in P. communis rhizomes increased in quadratic with increasing age class.

Key words: topographic effect, fractional vegetation coverage, Pisha sandstone, trend analysis