Birch mixture in spruce forest - a method to reduce the effects of acidification?

Acidification has lately been focus of increased attention in the business, industrial and public sectors. One measure that can prevent further acidification is the liming of forest soils. Another strategy would be to increase the admixture of deciduous tree species in conifer forest. This paper deals with the latter problem. From ecological and economical standpoints, the tree species offering the most advantageous admixture in Sweden would be birch, Betula pendula, and Norway spruce, Picea abies. Birch trees help to increase soil pH, while decreasing atmospheric deposition and protecting young spruce seedling from frost. The use of birch admixture need to be 50% or more to get required effect. This will lead to a reduction in spruce wood production. This need not to be a problem, however, since birch pulp will probably become more valuable in the future. The admixed forests have a higher biological diversity and are of greater value for recreation. Although spruce production on acidified sited is still high, further atmospheric deposition could lead to declines in production. Forest soils will eventually sustain serious damage if acid deposition continues to increase, which will require new alternatives for wood production be found. A high admixture of birch can offer a temporary respite if emission and deposition continue, but cannot completely compensate for the acidifying effects of present deposition levels. 26 refs, 2 figs