The major forest types in Europe, from the Boreal to the Mediterranean region, all include a variable number of native vascular plant species in the understorey layer (1.3 m height), both herbaceous and woody. In spite of its small stature and biomass this layer can contain 90% or more of the plant species of the forest. The functional role of the understory vegetation has already been shown in previous studies on temperate forests. They can serve as: