Study On Aquatic Plant Diversity And Communities Characteristics Of Kaidu River Basin In Xinjiang Uygurautonomous Region

Kaidu river basin(E 82°?860,N 42°?43°),which is located in the south of Mount Tianshan and north of Yanqi basin,harbors unique aquatic plant diversity due to its diversity hydroclimate and landform.Although some prvious studies on macrophytes diversity have been carried out,the knowledge of the flora of aquatic vascular plants remains woefully inadequate in the Kaidu river basin.In this study,field investigations of aquatic vascular plants were carried out throughout the Kaidu river basin to study macrophytes distrubtion pattern and influencing factors.The main results are as follows:(1)The results obtained from the present field study showed that a total of 71 species belonging to 39 genera and 24 families in Kaidu river basin.Among these,1 family,1 genus and 2 species belong to Pteridophyte,69 species,38 genera and 24 families belong to angiosperm.From life form,macrophytes in Kaidu river basin can be divided into emergent aquatic plants,submerged plant,floating-leaved plant and free-floating plant.Among them,the number of emergent aquatic plant ranked first,followed by submerged plant,floating-leaved plant and free-floating plant.(2)According to family distribution areal type,aquatic plants in Kaidu river basin can be divided into cosmopolitan families(21 families,87.5%)and north temperate zone families(3 families,12,5%).From genera distribution areal type,macrophytes in Kaidu river basin can be divided into 5 distribution areal types.Among them,cosmopolitan genus(26)ranked the first,followed by north temperate zone genus(5),north temperate zone and south temperate zone discontinuous distribution genus(5),Eurasian temperate and South America discontinuous distribution genus(1)and Old World temperate distribution genus(2).(3)?-diversity analysis of aquatic plants in Kaidu river basin indicated that there were significant difference between specie composition,rather than between family composition between upstream,midstream and downstream.(4)TWINSPAN community classification results showed that aquatic plants in Kaidu river basin were divided into 15 communities.There are Ass.Nymphaea tetragona-Potamogeton malaianus,Ass.Nymphoides peltatum,Ass.Typha angustifolia,Ass.Phragmites australis,Ass.Najas marina,Ass.P.pectinatus +Myriophyllum Spicatum,Ass.P.pectinatus-Halerpestes cymbalaria,Ass.Ceratophyllum demersum,Ass.P.pectinatus + Callitriche stagnalis,Ass.Ranunculus natans,Ass.Triglochin palustre,Ass.P.pectinatus,Ass.Hippuris vulgaris +Heleocharis vallcculosa,Ass.Triglochin maritimum and Ass.Halerpestes tricuspis.(5)RDA analysis showed that,pH explained 27%of the relationship between a-diversity index and environmental factors;altitude explained 19%of the relationship between ?-diversity index and environmental factors;longitude explain 18%of the relationship between ?-diversity index and environmental factors.The correlation analysis between environmental factors and 4 ?-diversity index of main aquatic plants community indicated that significant negative correlation existed between pH and Shannon-Wiener and Simpson index,and between longtitude and Simpson index.Also positive correlation was found between Simpson index and altitude.