**3.1.2 Alluvial formation**

The Alluvial Dense Rainforest grows in Fluvisols and Gleysols in alluvial plains influenced by mountain range sediments carried by rivers (Roderjan et al., 2002).

The canopy is usually 20-25 m tall and some expressive species of this formation are *Pseudobombax grandiflorum*, *Alchornea triplinervia*, *Ficus organensis*, *Andira anthelmia* and *Syagrus romanzoffiana*. *Inga sessilis, Coussapoa microcarpa, Psidium cattleianum*, *Ocotea pulchella*, *Myrcia insularis* and *Marlierea tomentosa* are also important in these communities (Roderjan et al., 2002; Pires et al., 2005; Zacarias, 2008).
