The clear-cuts cause considerable changes to forest ecosystems, including physical and chemical changes to understory vegetation. Forest restoration processes strongly depend on the degree of disturbance caused by this activity. Our aim was to assess short-term changes to Vaccinium myrtillus and V. vitis-idaea populations in Pinus sylvestris-dominated forests following the clear-cuts. Vegetative performance of V. myrtillus and V. vitis-idaea populations was determined for mature forest stands and for clear-cuts. Spectrophotometric tests of plant samples were used to measure the total phenolic compound content, as well as flavonoid content, together with free radical scavenging activity in both aboveground and underground parts of V. myrtillus and V. vitis-idaea. Statistical data mining using MATLAB v9.1 software was performed on vegetative characters of V. myrtillus and V. vitis-idaea, as well as on data relating to the antioxidant properties of these samples. Investigation of V. myrtillus and V. vitis-idaea revealed different responses following the clear-cut. We detected immediate changes in aboveground and underground parts, as well as in the number of individual shrubs of V. vitis-idaea and V. myrtillus after clear-cuttings. The both species showed higher vitality in Pinetum vaccinio-myrtillosum following the clear-cut. An increase in total phenolic and free radical scavenging activity was observed in V. vitis-idaea populations after clear-cutting in both types of forest.

Keywords: biomass, clear-cuts; phenolic compounds; Vaccinium.