Natural regeneration potential of the degraded Krkonose forests

Abstract

Self-regulating mechanisms and natural regeneration capacities still exist in the Krkonose National Park, although the magnitude of these varies with altitude. A study of changes after forest decline and clear-cut with respect to the establishment of pioneer trees, changes in the herb layer, changes in humus profile characteristics and soil base status was conducted in the Krkonose Mountains National Park in order to evaluate potentials for natural regeneration in forest affected by severe atmospheric deposition. Pioneer trees establish in both the upper and the lower supramontane zones. Even lowland species such as Fagus sylvatica appear to rejuvenate at high altitude, although in low numbers. Cover values of Betula pendula increase during clear-cut development, partly because they are avoided by deer; those of Sorbus aucuparia remain low due to browsing. In the upper supramontane zone changes in the herb layer are not significant: Calamagrostis villosa is dominant in (already declined) forests and remains so in clear-cut areas. In the lower supramontane zone Vaccinium myrtillus has its optimum in forests, while Deschampsia flexuosa strongly increases in clear-cut areas. Pioneer herbs establish after clear-cut. During clear-cut development, LF horizons decrease, due to a shift in input from low-decomposable spruce needles to easily decomposable grass (and later pioneer) litter. H horizons increase because of continuing decomposition and organic matter transfer from F to H. horizons. At higher altitude, these processes occur at a lower rate. Pioneer trees have ameliorating effects on the soil via an increase in base elements and pH compared to spruce forests. There are only few indications that pioneer trees are severely hampered by dense grass carpets, which may occur in particular microhabitats escaping attention in the larger plot descriptions. High grass covers instead seem to have stimulating effects on seedling establishment via the improvement of the humus profile, which continues after pioneer trees grow up. Copyright (C) 2000 John Wiley and Sons, Ltd.