**3.3.1 Alluvial formation**

This formation is distributed over riverine floodplains and some islands in the Paraná river, and also around some of its tributaries. The Alluvial formation occurs predominantly in soils with considerable hydromorphy, such as some Fluvisols, Entisols (Quartzipsamments) and Gleysols (Roderjan et al., 2002).

The Alluvial Semideciduous Seasonal Forest is characterized by a canopy about 15 to 20 m height and lower floristic diversity. Among the main species are *Cecropia pachystachya*, *Triplaris americana*, *Calophyllum brasiliense, Gallesia integrifolia* and *Chrysophyllum gonocarpum. Sebastiania commersoniana*, *Anadenanthera colubrina, Acrocomia aculeata* and *Inga uruguensis* are also common (Leite et al. 1986; IBGE, 1992, Roderjan et al., 2002; SEMA, 2002; Costa Filho et al., 2006).
