Comparison of species composition and diversity of vascular plants and bryophytes in seminatural forests and spruce plantations

The effect of spruce plantations at sites originally covered by deciduous forests on understory species has only rarely been studied. The aim of this work is to compare the diversity and species composition of understory in natural stands dominated by European beech (Fagus sylvatica) and cultural stands dominated by Norway spruce (Picea abies). The study was carried out in the Blanský les Protected Landscape Area in South Bohemia (Czech Republic), where both cultural spruce forests and natural beech forests are available. Data for the comparison were obtained by means of phytosociological records. In total, 60 relevés were recorded (30 in beech and 30 in spruce stands). A maximum distance of 350 m between pairs of relevés was chosen to include similar habitat conditions for both stand types. The analysis shows that there is no significant difference in the diversity of plants in beech (13.43 species on average) and spruce stands (13.8). Nevertheless, species composition in the studied stand types is different. Beech forests are characterized by the occurrence of vascular species typical of mesophilous forests (e.g. Galium odoratum, Milium effusum, Luzula luzuloides) whereas mosses are more frequent in spruce plantations (Dicranella heteromalla, Dicranum scoparium). From the analysis of background environmental factors we found slope, aspect, coverage of tree layer, rainfall and stand type (beech/spruce) to be insignificant. In contrast, the factors sample pair (i.e., pure effect of the locality) and altitude are significant and explain most of the variability in species composition.