Forest acidification and the socio-economic costs.

The continuing anthropogenic acidification of forests soils in Sweden is a serious threat to the longevity of these utilities. Anthropogenic activities can thus lower the total value the forest represents, which in turn would have a negative impact on the welfare of Swedish society. The acidification of soil results in the leaching of plant nutrients (Falkengren-Grerup 1995) such as potassium, calcium, and magnesium, which in the long term can cause nutrient deficiencies (Thelin et al. 1998), threatening the productivity of forest soils. The process of acidification also results in elevated concentrations of dissolved aluminium and other toxic metals in the soil, ground water, and surface water (Berggren et al 1990; Johansson et al 1995). Biodiversity in lakes and rivers in areas affected by water acidification is seriously impoverished (Brodin and Henriksson 1995). Acidified ground water can cause problems of various sorts, such as the by corroding of pipe-work (Bertills et al. 1989) and the creation of health risks (Bjertness and Alexander 1997), since the acidification increases the mobility of various harmful metals such as aluminum, mercury, copper, zinc, cadmium, and lead (Johansson 1995). Acid deposition accelerates the deterioration of building materials as well as of objects of art and of historical interest, particularly in urban areas (Kucera et al. 1996). The understanding of how forests are affected by acid deposition has improved significantly and it has become clear that many values in society are threatened by the ongoing acidification of Swedish forest soils (Johansson et al. 1999). There are measures of several kinds, apart from the lowering of the acid deposition, which can be carried out to mitigate such effects.