Alnus incana

Growing up to the forest line in the north, grey alder is an important pioneer species in the wild. Growing shrub-like at first, during its relatively short life it can reach almost 20m in fertile soil. By dropping its leaves while still green and fixing atmospheric nitrogen in its roots, grey alder improves the soil of sites like worked-out sand and gravel pits. It also provides an excellent protective canopy for less hardy species.