Growth analysis of the ramets of Phragmites australis in different habitats in Zhalong wetland

In order to explore the influence of habitat on growth and biomass allocation and the trade-offs for the ramets of Phragmites australis, a comparative study was performed on quantity characteristics, biomass allocation, and growth relationship of ramets of P. australis in different habitats in Zhalong wetland using a large sample survey and statistical analysis. The results showed that during the vegetative growth period of July, the height and weight of ramets and weight of modules of P. australis in these four habitats were largest in the aquatic habitat and smallest in the saline-alkali habitat. The difference between habitats reached a significant level (P < 0.05); the maximum values of height and weight of ramets were 2.7～4.5 times and 4.9～18.8 times the minimum values within the habitat, and 2.9～4.6 times and 3.6～4.6 times among habitats, respectively. The coefficient of variance of ramet height among habitats (48.05%) was higher than that within habitat (24.87%～40.51%), and the coefficient of variance of ramet weight and the module between habitats (42.26%～64.09%) was lower than that within habitat (55.79%～99.76%). The biomass allocation ratios of leaves, leaf sheaths, and stems ranged from 27.79%～38.29%, 17.93%～25.66%, and 36.05%～54.14%, respectively. The relationship between ramet height and leaf weight, leaf sheath weight, stem weight, and ramet weight was a power function allometric scaling relationship, while the relationship between ramet weight and leaf weight, leaf sheath weight, and stem weight was a linear function isokinetic scaling relationship. The ramets of P. australis in different habitats had greater ecological plasticity with increasing height and weight. The growth of ramets was controlled by both genetic and environmental factors, and the growth relationships among the modules were highly conservative. This indicates there was a significant relationship between resource allocation and trade-offs among different modules of ramets of P. australis in different environments.