Studies On The Hygrophyte In The Section From Yibin To Jiangjin In The Upper Yangtze River

Riparian Hygrophyte are an important component part of riparian ecosystem, it takes a key role in material and energy recycling, contaminants resorting and filtering, riparian stability and structure maintaining, and river ecosystem functional continuity keeping, etc. between water and land ecological system. The current study focus on surveying of habitat conditions, flora distribution, and community characteristics of Hygrophyte community, and using Hygrophyte to assess river ecosystem health of the upper Yangtze River (from Yibin to Jiangjin), from November 2013 to July 2014. The methods of field investigation combined with laboratory experiments were used. The results are as follows:1. In the current investigation, we obtained total 60 Hygrophyte species, distributed in 22 families, and 54 genera. The major families are Gramineae (11 genera,11 species,16.67% of total species), Asteraceae (nine genera, nine species,15% of total species), and Polygonaceae (two genera, six species,10% of total species) from the surveying river section.2. Based on the study of Hygrophyte flora composition, on the family level, the major distributed Hygrophyte are families of cosmopolitan,90.91% of total families, combining with the minor distributed Hygrophyte which belong to the families of pantropic, and Trop. Asia to Trop. Africa. While, on the genera level, the major distributed Hygrophyte still are genera of cosmopolitan, 31.48% of total genera, and then are genera of north temperate and pantropic,24.07% and 23.37% of total genera, respectively, five genera (9.26%) are old world temperate.3. The Shannon-Wiener index of Hygrophyte is in the range of 0.37 to 1.57, the Pielou index of Hygrophyte is in the range of 0.05 to 0.27, the Margalef index of Hygrophyte is in the range of 0.55 to 4.28 in our surveying river section. All these indexes suggest that, from Yibin to Jiangjin river section, the river ecological function is very weak, hygrophyte diversity degree is low, the population distribution is more concentrated, species Pielou index was low. The Hygrophyte biomass display a gradually increasing trend from January to July in the annual period. Furthermore, when we evaluate the percentage of common species between any two different sampling area, we found that more close of the sampling area, more similarity of common species.4. According with Hygrophyte characteristics, we try to setup a model to evaluate healthy condition of the river. Eighteen biologic factors are analyzed, and 4 factors, F (M3), G (M5), species percentage of Gramineae (M12), and average coverage (M16), are secreted to setup HP-IBI model. The results indicated that the river healthy level is health at Jiangan section, sub healthy at Baisha, Deganba, Yibin, and Gaozhuang briGe section, while generally at Yangshi section. Together, the river healthy condition is good in our surveying river section. In the current study, we obtained a useful model to evaluate river healthy condition according with Hygrophyte characteristics, which fit to upper Yangtze River, furthermore, this model will be a good reference for other rivers.