Study On Dynamic Changes Of Root Characteristics Of Dominant Emergent Plants In Nanji Lake Wetland

Strengthening the study of root function traits is of great significance for further revealing the underground ecological processes and mechanisms,and understanding the relationship between environmental factors and wetland ecosystems.In this study,the Nanyang Wetland National Nature Reserve,a typical area of Poyang Lake Wetland,was selected as the research area.The dynamics of above-ground(Plant height,Stem and Leaf biomass)and underground traits of three emergent plants in Nanji wetland,Phragmites australis Trin.ex Steud?Triarrhena lutarioriparia L.Liu?Zizania latifolia Turcz.ex Stapf,dynamic changes of plant underground functional traits(Underground biomass,SRL,RTD,Branching ratios,Branching intensity),nutrient contents(C?P?N)and stoichiometry(C/N?N/P)based on the root branch order of the Primit order proposed by Pregitzer,to explore the dynamic characteristics of plant characters in wetland and the differences among species,to analyze the adaptation strategies of three emergent plants to the natural environment,and to provide a reliable way to further reveal the coexistence mechanism of plant species in Nanji wetland and the response mechanism to environmental changes.The research results showed that:(1)The fluctuations of Plant height,Stem and Leaf biomass and Underground biomass of three emergent plants in the Nanji wetland of Poyang Lake showed strong regularity,and the Plant height increased with increasing growth time in different growing seasons.The trend of stem and leaf biomass and underground biomass increased continuously in the early and middle stages of the growing season,and decreased in the late;there was a significant positive correlation between Plant height and Stem and Leaf biomass,and Stem and Leaf biomass and Underground biomass did not exist.(2)The SRL,RTD and Branching intensity are different in the first orde of the three emergent plants.and the second root and third root do not show significant differences,while the Branching ratios are in the first and second grades.Roots do not have interspecies differences.The SRL of the three plants in different growth seasons was higher than that in the early and late growth seasons.The differences in RDT and seasonal variation were small,and the Branching ratio and Branching intensity decreased in the middle and early stages of the growth season.(3)The contents of C,N,P,C/N and N/P in different root orders of three wetland plants were significant.The C content,C/N and N/P increased with the root order increase,but the N and P content decreased.Among the species,the root order of Phragmites australis Trin.ex Steud and Triarrhena lutarioriparia L.Liu had significant differences in C,N,and P content and their stoichiometry characteristic,while Zizania latifolia Turcz.ex Stapf did not show differences in root order.With the growth of plants,the C content and C/N of roots increased.On the contrary,the N and P content and N/P decreased.