LONG-TERM INFLUENCE OF LARGE FOREST FIRE ON GROUND VEGETATION

Fire is a major disturbance in hemiboreal forests; it affects not only trees, but also ground vegetation. Previous studies have analysed the succession of ground vegetation after the fire, but not addressed the impact of the size of the burned area on revegetation of it. Therefore, the aim of our study was to assess the differences in post-fire ground vegetation in relation to the distance from the edge of the affected area. Vegetation data were collected using Braun-Blanquet method in three sites (122 sample plots) affected by forest fire and five clearcuts (not affected by fire) (92 plots), all regenerated by Scots pine 6 - 7 years before the assessment. The number of ground vegetation species (in all sites predominantly birds or wind dispersed) as well as their projective cover was not affected by the distance from the nearest edge of burned or clearcut, except in burned sites on dry sand soil (Vaccinosa and Myrtillosa), where herbaceous plant and shrub cover was decreasing (from 23.5% to 11.6%) and bryophyte and lichen cover - increasing (from 3% to 13.9%) with an increasing distance from the edge of the area. The total number of plants in burned areas was twice smaller than in clearcut in the same soil conditions but such large difference in projective cover was not observed. There were no significant differences between burned and clearcut areas in respect to Ellenberg's indicator values on both soil types, as well as no trend in Ellenberg's values for soil moisture in relation to distance from the nearest stand edge.