The Ecological Characteristics Dynamic of Phragmites australis Community in wetland of Semi-arid Areas——A Case of Momoge Wetland

Based on the observation data of ecological characteristics of Phragmites australis community and the situation of flooding in Momoge National Nature Reserve during growing season in 2007,the dynamic changes of Phragmites australis community growth and the water flooding dynamics were analyzed to study the seasonal changes of ecological characteristics of plant community and the impacts of flooding changes in semi-arid areas wetlands under natural state.The seasonal changes of coverage,height,density,above ground biomass of Phragmites australis community and the influence of the changes of flooding depth were analyzed in detail.The results showed that:growth process of Phragmites australis community had obvious seasonal regularity.The coverage of Phragmites australis community gradually increased with the seasonal change,reaching the highest level in the end of August and early September.The height of Phragmites australis community continued to rise until the end of growing season.The density of Phragmites australis community firstly increased and then decreased.The ground biomass of Phragmites australis community gradually increased with the season and its peak appeared in the end of August and early September,and then reduced because of impacts of its growth regularity.The depth of flooding had an important influence on the growth process of Phragmites australis community.The relative growth rate of height,density and above ground biomass showed significant positive correlation with the changing rate of depth of flooding(n=5,p0.05);while coverage was mainly affected by its growth rhythm,the correlation between coverage and the depth of flooding was not obvious.