Crack willow
Salix fragilis
The crack willow is a medium-sized deciduous tree reaching heights of up to 20 meters, characterized by a furrowed bark and a spreading crown. Its leaves are narrow-lanceolate, up to 15 cm long, and have finely serrated margins. A distinctive feature is the extreme brittleness of the twigs at their base, which gave the species its name. It prefers to grow on the banks of flowing waters and in moist lowlands.
Details
Habitat function
Important structural element in softwood riparian forests; root systems provide shelter for fish; nesting site for cavity nesters.
Nutrient uptake
High capacity for uptake of nitrogen and phosphorus from near-shore groundwater.
Food source for
Bees, hoverflies, caterpillars of over 100 butterfly species (e.g., eyed hawkmoth).
Human use
Bark for extracting salicin (natural remedy); weaving material (limited); wood for light construction and fuel.
Ecology
Ecological role
Pioneer tree species in floodplains; stabilizes riverbanks and provides habitat for specialized insects and birds.
Natural predators
Larvae of the goat moth (Cossus cossus), willow leaf beetles, various fungi such as the willow bracket.
Competitor species
White willow (Salix alba), European alder (Alnus glutinosa), hybrid willows.
Ecosystem service
Erosion control on banks, filtering of surface runoff, provision of early spring forage for pollinators.
Threats
Loss of retention areas due to river channelization, hybridization with Salix alba, invasive neophytes.
Scientific profile
Profile
Protection & threats
Main threats
Loss of natural river dynamics, hybridization with Salix alba (forming Salix x rubens), river channelization, and lowering of water tables.