This alpine valley has a mild, humid climate as a result of the föhn wind from the Rhine valley. Twenty-five kilometres of the valley is covered by near-natural montane and subalpine forest. This consists mainly of species-rich, old-growth stands of broadleaved deciduous forest and mixed forest, interspersed with pioneer communities along ravines and avalanche tracks, and dwarf pines Pinus on rocky slopes. Forestry activities are limited to a few sites.
An important site for forest species.
Pressure/threats to key biodiversity
Threats include forest dieback as a result of acid rain (`Other' threats, above), exacerbated by traffic pollution from the valley floor, and high levels of grazing by deer preventing regeneration. Problems of access are likely to limit an expansion of forestry.
National None International High1,500 ha of IBA covered by Special Protection Area (Bergwälder Klostertal, 1,500 ha).