Understory dynamics after disturbance accelerate succession from spruce to beech-dominated forest - the Siggaboda case study

Context: It is assumed that climate change will favour European beech (Fagus sylvatica L.) to Norway spruce (Picea abies [L.] Karst.) at its northern range margins due to climate change and induced disturbance events. Aims: An old-growth mixed forest of spruce and beech, situated near the northern beech margin, was studied to reveal effects of disturbances and response processes on natural forest dynamics, focussing on the understory. Methods: We carried out analyses on understory dynamics of beech and spruce in relation to overstory release. This was done based on a sequence of stand and tree vitality inventories after a series of abiotic and biotic disturbances. Results: It became apparent that beech (understory) has a larger adaptive capacity to disturbance impacts and overstory release (68 % standing volume loss) than spruce. Understory dynamics can play a key role for forest succession from spruce to beech-dominated forests. Disturbances display an acceleration effect on forest succession in the face of climate change. Conclusion: Beech is poised strategically to replace spruce as the dominant tree species at the study area. Due to an increasing productivity and a lower risk of stand failure, beech may raise into the focus of forestry in southern Sweden.