Changes Of Nutrition Eements And Microbial During Decomposition Of Phragmites Australis

Lake-side has a unique ecological significance as a link of water and land. Litter decomposition of wetland plant plays a key part of cycling of wetland nutrient and energy flow.Litter decomposition of wetlands is still the least part of functions and procedures we study for,which is a complex process of physical, chemical and biological.Phragmites australis as a major emergent application of mature plants,with is used widely in restoration project because of its high biomass,high N,P absorption, low cost and effect of a beautiful landscape.This reasearch took litter of Phragmites australis in East Taihu Lake as materials,using laboratory litter bag technique to study decomposition of different water level and explore the relationship of nutrients,microorganisms and sediment during decomposition of macrophytes..The research showed there was a fast decomposition rate during early experiment.The rate of the whole experiment was 50% flooding(0.0017d-1)> full flooded (0.0010d-1)> no flooding (0.0009d-1).The changes of reduce of biological was significantly different (p<0.01) with time, and the changes in biomass was significantly different (p<0.05) in three cases.Organic matter content changes were significantly decreased (p<0.05) with time.TN,TP had no significant difference (p> 0.05) with time.The annual loss rate of TN, TP was greater than biomass.During decomposition,fungi and actinomycetes were the main decomposers, and the amount of bacteria increased over time.The decomposition of bacterialunder was far more than the fungi and actinomycetes under 50% of the flooding. When completely submerged,actinomycetes were the main decomposers. The bacteria was the highest in sediments,followed by actinomycetes and fungi at least,this phenomeonon was related with the pH of sediment which is alkaline and poor ventilation.The changes of biomass of Phragmites australis litter were significantly correlated (p <0.01) with sediment organic matter content, sediment pH and sediment,which was negatively correlated with microbial biomass,correlation was not significant.