To determine population number and community characteristics of remnant populations of endangered Myricaria laxiflora
(Franch.) P. Y. Zhang et Y. J. Zhang, we investigated and analyzed the species composition, population number, species biodiversity, floristic composition, and life-form of M. laxiflora
populations in the Yangtze River Basin downstream of the Three Gorges Dam (Dianjun, Zhicheng, and Dongshi islands). Results showed 83 species, 73 genera, and 38 families of plants in the distribution area of the remnant M. laxiflora
populations. The shrub community was dominated by M. laxiflora
and Salix variegate
Franch. The M. laxiflora
population was only distributed in clusters in the flooded areas in summer and exposed areas in winter, with poor community stability. The M. laxiflora
population consisted of about 222 300 individuals in Dianjun island, 774 700 individuals in Zhicheng island, and 197 400 individuals in Dongshi island. For the three distribution areas, the species richness index was 10.5 – 11.5, Shannon-Wiener index was 1.21 – 1.54, Pielou index was 0.74 – 0.91, and Simpson index was 0.53 – 0.69, indicating that species biodiversity was low. The vegetation distribution areas were characterized as North Temperate and Pantropic, similar to the vegetation floristic composition of subtropical regions in China. However, life-forms were mainly geophytes and therophytes, similar to the tropical and subtropical desert climate vegetation type.