Klibbalens gödslingseffekt på volymproduktionen i ett blandbestånd av gran och klibbal
en simulering i Heureka
A secondary and a pioneer tree species can with advantage be included in a mixed stand to increase the use of sunlight. Nitrogen-fixing plants have been shown to increase the supply of nitrogen in the soil by, for example, litter fall. This deposition acts as a biological fertilization, which may be used by non-fixing plants. Alder is a nitrogen-fixing, pioneer tree species that loses its nitrogen-rich leaves late in the autumn. The aim of this study was to examine the effect on the total volume of production, when different proportions of nitrogen-fixing Alder were part of spruce stands. A second goal was to identify at which approximate proportion of Alder the highest volume production was achieved. In Heureka StandWise a mixed population consisting of various shares of spruce and alder (0%, 30%, 45%, 60%) with each three different management programs (no thinning, one thinning, two thinnings) were simulated. The results showed that 30% Alder, in the mixed stand, gave the highest total volume production regardless of the management program that was used. This may indicate that the optimum probably lies close to this value. The average amount of nitrogen in the simulations ranged between 9 to 19 kilogram per ha and year. Positive side-effects which follow this type of species mixture is increased frost protection and increased storm resistance for spruce. The results of this study could form an idea and inspire further research on how forests of this type can be established and managed.