Norwegian Journal of Agricultural Sciences : forest decline in Norway: monitoring results, international links and hypotheses

Abstract

It is widely accepted that forest decline is a multiple syndrome and that there is less synchrony in its incidence than was previously thought. T'here are also some doubts as to the «novelty- of some kinds of damage, e.g. magnesium deficiency and damage associated with needle fungi. Nevertheless, the appearance of so many ailments in the forest at roughly the same time suggests that there are linking and triggering factors. The large-scale surveys of forest damage are useful and very important for identifying and quantifying the problems with novel forest decline, but the scientific quest for its causes can probably be carried out only through detailed work in long-term studies of forest ecosystems. Models of nutrient cycling are necessary tools for revealing the true status of health in our forests. A continuation of the present pollution loads for extended periods of time or an increase in pollution Ievels may threaten the vitality of forests over large areas of Europe. A reduction in air pollution loads would improve the condition of our forests and postpone a possible expansion of forest decline. The important role of forests and the threat of global warming as a result of the possible greenhouse effect support the need for further measures to reduce air pollution.