Spatial pattern of Norway spruce and silver fir natural regeneration in uneven-aged mixed forests of northeastern Bohemia

Two permanent sample plots (both 0.25 ha) were established in a mixed forest in the Orlické hory Mts. Protected Landscape Area (northeastern Bohemia) to analyze the natural regeneration of Norway spruce (Picea abies [L.] Karst.) and silver fir (Abies alba Mill.). All the seedlings (height 0.1-0.5 m), saplings (height 0.5 m, d1.3 3 cm) and trees (d1.3 > 3 cm) were localized and measured. The analysis of the spatial pattern and statistical evaluation were carried out by means of Ripley's K-function. All the growth stages of the spruce and the fir showed an aggregated (clump) pattern, whereas the regeneration of fir was positively correlated with mature spruces and the regeneration of spruce was in a positive relation with mature firs. The results indicate that for germination and stable growth in the first stages of development, the fir can find more favourable conditions under the crowns of spruce trees and the spruce under mature firs.