Keeping mixtures of Norway spruce and birch in production forests: insights from survey data

Admixtures of birch in Norway spruce plantations are being promoted as a means to increase habitat and species diversity. The implications this mixture were analysed with regional survey data from southern Sweden. Permanent sample plots the Swedish National Forest Inventory (NFI), admixture birch, used describe temporal trends admixture, regarding composition competitive strength. Observations thinned show higher harvest removal (35%) than for (19%). without thinnings period before measurement showed that individual tree growth was lower compared it decreased even more increasing stand age competition. In addition, complementary field survey, multiple distributed each stand, detect within-stand variation density. Although heterogeneity larger mixed stands terms composition, not different monocultures These two surveys several reasons, decreases over although increases diversity, does necessary imply change