Ecological succession of aquatic macrophytes on floating meadows in the Pantanal wetland

With the aim of documenting aquatic macrophyte succession on floating meadows and its relationship with histosol thickness, we sampled six-hundred 0.5 × 0.5 m2 plots of ten randomly chosen floating meadows in Baía Grande lake (Aquidauana, MS, Brazil). The floating meadows were marked in order to follow, since August 2014–August 2015, floristic and phytosociological changes and to assess their relationship with histosol thickness. We recorded 58 species belonging to 23 families and 47 genera. The richest families were Poaceae (8 species), Asteraceae (7) and Cyperaceae (6). Four species stood out for their high importance value: Oxycaryum cubense (Poepp. & Kunth) Lye, Ludwigia helminthorrhiza (Mart.) H. Hara, Eichhornia azurea (Sw.) Kunth and Vigna longifolia (Benth.) Verdc. Histosol thickness of the floating meadows varied from 1 to 51 cm, making it possible to classify them into three classes. We observed that most species (63.3%) were in the initial and intermediate stages of succession (1–34 cm histosol) and that species were replaced as a function of histosol thickness. We conclude that floating meadows have succession stages with various species of aquatic macrophytes related with histosol thickness, but species composition regarding succession stages differs from other water bodies in the Pantanal wetland.