Changes in carbon allocation patterns in spruce and pine trees following irrigation and fertilization.

The paper presents an overview of the results of long-term fertilization and irrigation experiments in stands of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.). Large increases in stemwood production during the first 12 years of the experiments were achieved by fertilization especially when a balanced mixture of macro- and micronutrients was applied. The effect of irrigation alone was small, but it greatly enhanced the response of the ground vegetation to the application of a balanced fertilizer. Fertilization did not greatly affect the leaf/stemwood biomass ratio, but reduced the ratio of fine roots to total biomass. Drought reduced the coarse-root biomass/fine-root biomass ratio.