Natural Forest Reserves (NFR) are forested areas where the natural evolution of the forest ecosystem can be observed without any human interference. NFR should provide examples of naturally found mixed tree communities and flora when they are left untouched. Forest management, removal of dead wood and artificial seeding of forest trees is prohibited by agreement; however, hunting is still possible.
Both Natural Forest Reserves in the Windach Valley East of Sölden were enacted in 1998 in accordance with the National Program for NFR. They include about 135 ha (333 acres) and cover an area between 1800 and 2200 m above sea level. The Windach Valley NFR is characterized by Larch-Swiss Pine forests growing on silicate, which in many areas have already developed into maturity. There are some trees that are up to 300 years old, but on average they are 150 years. The tree communities serve a protective function as a result of their varied composition and age differences as well as their stages of decomposition.