The stand development of "forest of age classes" in TANAP after the wind disturbance

The paper presents the results of research of forest stands partly managed by irregular shelterwood system. There were the initial stages of fir and spruce natural regeneration present on the plot. The permanent research plot (PRP) was established in 1999. The regeneration felling was marked and subsequently performed in the same year. This stand was affected by wind storm in November 2004. The stand condition was evaluated in 2005. The total area secured by natural regeneration was 0.17 ha. The rest of the plot (0.08 ha), in form of scattered spots, showed no signs of natural regeneration. The analysis in 2010 confirmed that whole stand area including PRP was secured by natural regeneration of climax tree species (fir, spruce) and pioneer tree species (birch, goat willow). The height growth dynamics analysis of selected plots showed the same rate of height growth of both climax tree species in the advance growth stage. The height growth of spruce individuals was significantly higher in thicket growth stage. The fir maintains the position of middle and lower layer in vertical profile of advance growth stage or thicket respectively. There was determined successive birch invasion followed by consecutive arrival (with 2--3 years delay) of goat willow on the plot secured by regeneration of pioneer tree species. The average height of birch individuals was 4.01 m in time span from its origin in 2005 to presence. It represented the same height value as spruce had reached, that was in advance growth phase during the windstorm impact. The research confirmed that stands with realized regeneration fellings with initial phases of natural regeneration create the preconditions for achieving of the mosaic stand structure on the research plots in TANAP.