The Growth and Dynamics of Biomass of Reed Phragmites australis in Wetlands of Daguhe Estuary

Based on the data of reed Phragmites australis from the surveys conducted in wetlands of Daguhe Estuary between April and October 2009,the growth and dynamics of biomass of reed in main growth periods were analyzed.The results showed that average height of reed increased gradually in growth season with the lowest value of 117.07 mm in April and highest 2 305.35±65.48 mm in October.The density of reed showed a decreasing trend with the highest value of 362.33±24.52 shoots·m-2 in May and the lowest value of 255.0±36.17 shoots·m-2 in October.The average height of reed was uncorrelated with density of reed(P0.05).During the main growth season periods,the aboveground biomass of reed showed overall increasing tendency which reached the maximum point in October and exhibited evident changes monthly,ranging from between(37.59±13.94) to(7 033.02±967.37) g·m-2 for dry weight.Biomass of leaves,stem and sheath of reed increased generally from April to October.The dry weight was the highest in October at about(1 264.32±202.19) g·m-2,(3 667.58±475.22) g·m-2,(1123.78±178.37) g·m-2 for leaves,stem and sheath,respectively.F/C decreased gradually from April to October.Aboveground biomass of non-photosynthetic organs made a great contribution to the changes of total aboveground biomass.Preliminary study showed that rainfall had great positive effects on growth of aboveground biomass of reed in the wetlands of Daguhe Estuary.Underground biomass of each depth level showed a similar trend with no significant difference between months during the study period.The root/shoot ratio(R/S) of reed ranged between 0.29 and 1.93 from May to October.R/S was affected by environmental factors and was closely associated with variations in aboveground biomass and underground biomass.The growth of root was related to the self-regulation of reed,which could obtain survival conditions such as nutrition.