Abstract: To explore the mechanism underlying community stability of the invasive plant Alternanthera philoxeroides, we set up 73 plots (39 terrestrial and 34 aquatic) with a size of 10 m×10 m each in the latitudinal gradient from 21°N to 37°N in China. We calculated the Godron community stability coordinates and four α-species diversity indices, and measured seven environmental factors (longitude, latitude, elevation, NH₄⁺-N, NO₃-N, mean annual temperature, and mean annual precipitation). We used regression analysis and redundancy analysis to examine the effects of species diversity and heterogeneous habitats on the stability of invaded communities. The results showed that: (1) A total of 169 plant species were recorded in the terrestrial communities, belonging to 55 families and 147 genera, and the dominant species accompanying A. philoxeroideswere Digitaria Sanguinalis, Echinochloa crusgalli,Bidens pilosa andEleusine indica. A total of 107 plant species were recorded in the aquatic communities, belonging to 49 families and 92 genera, and the dominant accompanying species werePaspalum bipinnata, Ceratopteris thalictroides, E. crusgalliand Bidens pilosa. (2) Results of regression analysis showed that the stability of terrestrial communities decreased with the increases of Simpson diversity index, Shannon diversity index, and Pielou evenness index, whereas the stability of aquatic communities decreased with the increases of Pielou index. There was a unimodal change with the increases of Patrick richness index. (3) Results of regression analysis and redundancy analysis showed that the dominant environmental factors determining the stability of A. philoxeroides community in terrestrial and aquatic habitats were longitude, latitude, mean annual temperature, and mean annual precipitation. Among them, terrestrial community stability increased with the increases of longitude and latitude, but decreased with the increases of mean annual temperature and mean annual precipitation. However, the change ofaquatic community stability along the environmental gradient was opposite to that of terrestrial communities. These results indicated that the responses of A. philoxeroides community stability to species diversity and heterogeneous environments differ greatly between terrestrial and aquatic habitats. Under the rapid global environmental changes, more attentions should be paid to the monitoring of terrestrial A. philoxeroides community dynamics in high latitudes as well as aquatic A. philoxeroides community in heavy rainfall areas.

Key words: biological invasion, Alternanthera philoxeroides, community stability, heterogeneous habitat, species diversity, redundancy analysis.