Abstract: In the field survey, we selected 59 sampling plots along the latitudinal gradient (from 21°N to 37°N, which were belonged to 10 provinces and 20 cities) in terrestrial habitats of mainland China, to explore the species structure characteristics and association classification of invasive plant Alternanthera philoxeroides community by using two-way indicator species analysis (TWINSPAN) and de-trended correspondence analysis (DCA). In addition, we used the de-trended canonical correspondence analysis (DCCA) to operate the ordination of plant species distributions along environmental factors (longitude, latitude and elevation). The results showed that: (1) 59 plots totally recorded 170 plant species, which were belonged to 52 families and 134 genera, A. philoxeroides had a significant highest dominance (its total importance value was 32.390). The co-occurring plants which had higher occurrence frequency were Alternanthera sessilis(16/59), Polygonum hydropiper (13/59) and Digitaria sanguinalis (12/59); (2) TWINSPAN and DCA divided the A. philoxeroides community into 10 plant associations, A. philoxeroides+D. sanguinalis association had the highest occurrence frequency (8/59), D. sanguinalis was the main co-occurring native species in A. philoxeroides invaded community, and it could be considered as an potential replacer for A. philoxeroides through interspecific competition in the future; (3) DCCA ordination indicated that latitude was the crucial environmental factor which determined species’ distributions, TWINSPAN divided the 30 main plant species (which total importance value was more than 0.2) into ten clusters, distribution regions of each plant cluster on DCCA two-dimensional diagram were all consistent with classifications, the ordination position of Humulus scandens was very close to A. philoxeroides; (4) DCA and DCCA all reflected the water gradient of associations and plant species’ distributions, with latitude increasing, the plant species in filed A. philoxeroides communities gradually changed from mesophytes to hygrophytes. These findings were helpful for understanding the numerical characteristics and predicting dynamics of invasive plant community, as well as making effective measurements for future biological invasions.

Key words: Alternanthera philoxeroides, biological invasion, community, classification, ordination, environmental gradient