In the Alps the protective effects of forest vegetation were recognized as early as the 14th century and this aspect of forests kept preference to wood production until to-day. This contrasts the purely economic valuation of forests in Central Europe's plains around 1900, which gave way to a juster judgment only when the known classical forest influences, such as protection from soil erosion by water and wind, were reinforced by the modern ones, such as protection from factory fumes, noise, and radiation. Increasing importance of forests in water economy and as recreational areas supported this change of opinion which climaxes in to-day's demand for optimum balance of both economical and welfare aspects and use of forests. This development was greatly facilitated and promoted by the demonstrative investigations of Hans Burger.