A study was conducted in the natural riverbed of the Maggia near Cevio and Giumaglio in the Canton of Tessin. The course of the river had not been deliberately altered by man. The riparian vegetation dynamics were reconstructed from records of yearly maximum river flow, seven aerial photographs taken since 1935, observations on soil profiles, scars on the stems of trees, the presence of tension wood, and the shapes and ages of trees and shrubs growing along the river. Periodically, floods destroy the tree sites or sedimentation or erosion affect the ecology of the sites. Even though the trees and shrubs are adapted to extreme site conditions, they rarely become older than 20 years. Species characteristics leading to survival are: resistance to long periods of flooding, rapid vegetative regeneration of roots and branches, fast germination of seeds, rapid shoot growth, rapid healing of wounds, and effective comparimentalisation of rot within the tree. Alnus incana, Salix elaeagnos, and S. purpure are species most likely to survive in the river bed.
Dendrochronologically dated scars and observations on the beginning of tension-wood in the stems are especially useful in assessing the mechanical stress of floods on trees growing in the river bed and along the flood plain.