Changes of biologically active compounds in the forest litter during the vegetation of understory plants before and after clear cutting of forest

Abstract

The impact of forest clear cutting to the understory plants and insects populations, to the soil or forest litter is not clear and is discussible between scientists nowadays [1-3]. Therefore, the aim of this study was to evaluate changes of the total phenolic compounds content and antiradical activity in the forest litter at different collection times before and after clear-cutting of the forest. The samples of forest litter were collected considering the vegetation phases of understory plants of Ericaceae family, such as Vaccinium myrtillus, V. vitis-idaea, and Caluna vulgaris, in the tested forests. In the previous study, it was determined, that highest contents of phenolic acids are in aqueous extracts of C. vulgaris from one-year-old clear cuttings, which demonstrated a strong phytotoxicity on Scots pine seed germination [4]. Forest litter from Lithuanian Pinetum vacciniosum and Pinetum vaccinio-myrtillosum forest types were analyzed in the present project. Samples were collected in April (the beginning of vegetation of understory plants), in May (blooming of Vaccinium myrtillus and V. vitis-idaea), in July (development of V. myrtillus and V. vitis-idaea berries, and blooming of C. vulgaris), and in November (the end of the vegetation of the understory plants). Total phenolic compounds content and antiradical activity varied in the samples depending both on the forest type and collection period. The reduction of total phenolic compound content and antiradical activity was observed after clearcutting in the samples collected in Pinetum vacciniosum forest type; while the content of total phenolic compounds in the samples from Pinetum vaccinio-myrtillosum remains constant during three periods out of four, and the reduction was noticed in the samples collected in November. Antiradical activity of two samples from this forest remarkably increased, and slightly was reduced in one sample