The paper analyzes data sets from three regions: 34 permanent research plots in the Orlické hory Mts. (1951-2001); 32 plots in the Giant Mts. (1980-2005); 20 plots in the Bohemian Forest (1997-2007). Each plot was studied using repeated plant-coenological relevés. Plots were clustered into groups regarding dominant species in the tree etage (Fagus sylvatica and Picea abies), the dieback of the tree etage and altitudinal zone.
The plot change during the investigated period represents a temporal gradient. Such gradient can be described by Α-diversity at each time of sampling and by Β-diversity as a measure of community dynamics. Two new indices dH and dS based on Shannon-Wiener's index and species richness are introduced and used.
Separate community etages show more or less different dynamics during forest succession. Rapid tree stand damage as a result of bark beetle (Ips typographus) gradation was recorded in the Bohemian Forest as an effect of climate extremes. Gradation of bark beetle can be of natural origin. The tree etage decline in the spruce forests holds lower importance in species composition than has been mentioned earlier.
Beech-mixture forests shows higher changes, without a complete tree etage decline, compared with spruce forests with completely dying trees, because the herb etage shows higher species richness and many of the species is very sensitive to changes.