Study On Ecology Of Wetland Vegetation In Mang River Watershed, Shanxi

The wetland vegetation of Mang Rriver Watershed, shanxi wasstudied by quantitative ecological methods, including theclassification, ordination, species diversity, floristic andinterspecific association based on the dataset from the field inorder to offer scientific reference for the sustainable use andmanagement of the wetland resources and ecological environmentof Mang River.(1)45plots were investigated in the field, the results showedthat there were totally104species belonging to83genera and43families in the vegetation of Mang River Watershed. The hygrophyte,the hydrophyte and the mesophyte were dominant copsitions in thefloristic element.Asteraceae was the family with the richestspecies, next was Gramineae, Gramineae and Ranunculaceae. Theflora of156seed plants founded in the community was classifiedinto11areal types, of which North Temperate elements and Worlddistribution elements, Pantropical distribution and Old worldelements, and North Temperate elements and World distributionelements dominated in the communities.(2) Based on the data collected from216quadrats,the classification and ordination of the communities of Mang RiverWatershed were studied by using two-way indicator speciesanalysis (TWINSPAN),detrended correspondence analysis (DCA)and canonical correspondence analysis (CCA). According to theresults of TWINSPAN classification,216quadrats were classifiedinto15association types.The results of plots from DCA ordinationnot only exhibited the similaritive classification results to that ofTWINSPAN, but also reflected the relationship between associationtypes and environmental gradient, that is, the first axis of DCAmainly reflected the position change in the soil moisture, and thesecond axis of DCA indicated the change of the contents of the soilorganic. All these results showed that the species composition anddistribution of the communities were affected mainly by slopeposition and elevation change.The ecological meaning of CCAordination axes is much clearer than that of DCA axes. CCAordination can simultaneously express similaries of species withenvironment, and the quadrat location of CCA ordination is muchcloser to each other than that in DCA, and the boundary amongforest communities become more ambiguons. Therefore ifordination is combined with classification, the effect of DCA isbetter than CCA.(3) Three diversity indices were applied to analyze the speciesdiversity characteristics of Mang River Watershed community. Theresults show that all these indices could effectively reflect thecharacter of communities, such as the structure and habitat.Meanwhile, they also reflect the particularity of composition andstructure of Mang River Watershed community.The species diversity indices of Assoc. Lythrum salicaria+Potentillaanserina+Girardinia diversifolia was the largest, and the next wasAssoc. Commelina communis+Mentha haplocalyx Briq＋Artemisialavandulaefolia＋Bidens pilosa. Using the analysis from the diversityindices, it shows that human disturbances, community dynamics andhabitat types are influential factors for species diversity, with humandisturbances and habitat types to be the majoy factors.(4) Jaccard index and χ2test with2×2contingency table wereused to analyze the interspecific association among666species-pairs of37dominant species of Mang River Watershedcommunities. Additionally, Pearson correlation coefficient andSpearman rank correlation coefficient were also applied toinvestigated between species. The results showed that the numbersof positive correlated species-pairs were more than negatives.Compared with χ2test and Pearson’s correlation coefficient test,Spearman’s rank correlation coefficient test was an effectivemethod with χ2test and Pearson’s correlation coefficient test,Spearman’s rank correlation coefficient test was an effectivemethod to study the relationships between species.Moreover, basedon the results of the PCA, the37dominant species were divided intofour ecospecies, namely, aquatic, hygrophyte, hygrophytemesophyte and mesophyte.