The Ecological Plasticity Of Phragmites Communis Population In Restoration Succession Series With Flooded Meadow In The Songnen Plains Of China

Phragmites communis,which is a typical clonal plant of grass family with rhizome,has a broad ecological adaptation.This experiment on Phragmites communis population was conducted on four stands in different growth seasons and the ecological plasticity of ramets module was analyzed statistically.The results indicated: With the elongation of the flooding durations,there were some differences in the spatial dynamic change on Phragmites communis population characters and the characteristics were mostly influenced by the environment.There was a highest height on Phragmites communis population in fourth stand with longest flooding durations,and there were the most density and biomass in third stand.But the above reached minimums in first stand with shortest flooding durations. The quantitative characters of Phragmites communis population,such as the height,above ground biomass,biomass of stems and leaves showed the increased regulation of change.There was obviously significant difference within stands (p<0.01) and significant difference among stands (p<0.05).The ecological plasticity of ramet module on Phragmites communis population,was smaller variations within stages than those among stages,and among stands than among stages.There were smaller variations within stands than among stands in June and August,but larger variations in July.The ecological plasticities of ramets height were far smaller than biomass within stands and among stands,the same as those within stages and among stages.The sensitivity degree in respond to environment changed of the ramet biomass were far higher than height in Phragmites communis population. The biomass allocation in leaves was decreased with the height increased in Phragmites communis ramet,but the biomass allocation in stems was increased.The biomass allocation in stems in fourth stand reached maximum on every growth period,which was respectively 49.30%,56.31% and 62.71%.There were smaller variations among populations than within populations on the biomass allocation in stems and leaves,and kept stable comparatively among populations. The biomass of ramet module on Phragmites communis population were increased by power function with the ramet height increased in different stands,and the increasing speed on biomass allocation in stems was higher than leaves obviously.The definitive coefficient R2 of fitted equation was between 27.21% and 95.17%,and correlation coefficient r was between 0.5216 and 0.9756.They all reached extremely significant levels.Both the increased height and weight of ramets had a stable regulation of the heterogeneous speed. The biomass of ramet module on Phragmites communis population were increased by power function with the ramet biomass increased in different stands.It was between 69.95% and 97.46% that definitive coefficient R2 of fitted equation about biomass of stems,and it was between 69.62% and 98.51% about biomass of leaves.There was extremely similar power value b of increasing speed about biomass of stems in every stands,and the power value b was between 0.858 and 1.2074.But the power value b about biomass of leaves was between 0.8094 and 1.2312,and two groups of power value b were closed to 1.Both the increased weight of ramets and every component showed a stable regulation of the heterogeneous speed in different stands and stages.