The country's long-standing commercial use of the Alps for recreational purposes has also come under examination. Extensive tourism places an inordinate amount of pressure on sensitive Alpine ecosystems. Ski runs damage forests, as do summer sports such as off-trail mountain hiking or mountain biking. Many Alpine villages have also grown greatly because of the tourist industry. In extreme cases, they have up to twenty hotel beds for each inhabitant, a ratio that places a disproportionate seasonal burden on communal infrastructures and the environment. For these reasons, efforts have been made to introduce "green" or "soft" forms of tourism that are more compatible with the Alpine environment.