Biodiversity fosters the functioning and stability of forest ecosystems and, consequently, the provision of crucial ecosystem services that support human well-being and quality of life. In particular, it has been suggested that tree speciesdiversity buffers ecosystems against the impacts of disturbances, a relationship known as the “insurance hypothesis”.
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:
