Zmeny v štruktúre vegetácie alpínskeho vegetačného stupňa Vysokých a Belianských Tatier

Abstract

In the framework of the research project ”High mountain ecosystems in the Western Carpathians, ecological causes of man activities (No. VI–4–4)”, floristic and structural changes in alpine plant communities caused by immissions, acid rains, and man trampling was studies in the 10 monitoring plots (50 × 50 cm) in the period 1986-96. Five monitoring plots (1. under the peak Priehyby, 1 945 m a.s.l.; 2. the Furkotská valley, near the lake Nižné Wahlenbergovo pleso, 2 060 m a.s.l.; 3. the Furkotská valley, under the peak Predné Solisko, 2 075 m a.s.l.; 4. the Velická valley, under the Kotlový peak, 1 850 m a.s.l.; 5. the lake Skalnaté pleso, under the Lomnický peak, 2 050 m a.s.l.) were set in the community Juncetum trifidii, two plots in Festuco pictae–Calamagrostietum villosae (1. Zadné Meďodoly, the ridge between Predný žľab and Široké sedlo, 1 610 m a.s.l.; 2. the valley of Siedmich prameňov, the slope under the Murárikova wall, 1 640 m a.s.l.), Carduo glaucini–Caricetum tatrorum (1. Zadné Meďodoly, the slopes near the Široké sedlo, 1 820 m a.s.l.; 2. the Bujačí peak, the slope in the end of the Babia valley, 1 910 m a.s.l.), and Saxifrago caesiae–Caricetum firmae (1. Zadné Meďodoly, the slopes near the Široké sedlo, 1 820 m a.s.l.; 2. the Bujačí peak, the slope in the end of the Babia valley, 1 910 m a.s.l.). The monitoring plots were set in the relatively intact communities and in the communities on tourist rails effected by trampling. In two plots, vegetation and soil layer were removed to study the succession process. In the association Juncetum trifidii, totally 2 200–2 700 ind. were estimated in the intact plots, while only 1 100 ind. were found in the disturbed by trampling and erosion. Trampling significantly decreased the abundance of Juncus trifidus and increased. Epigeic lichens of genera Cetraria and Cladonia were even more sensitive to trampling. In contrast, lichen Polytrichum piliferum increased. In the association Juncetum trifidii, abundance of Juncus trifidus and Festucha supina fluctuated, Oreochloa distichta and Luzula alpino-pilosa declined, and Campanula alpina increased. Production of green biomass declined from 215.6 g/m²/year to 146.0 g/m²/year, yet production of dead biomass increased from 72.4 g/m²/year to 116.4 g/m²/year in the Velická valley. Explanation of the described pattern by the damaging effects of immissions and acid rains is not, however, straight forward due to possible effects of climatic factors and effects of vegetation destruction resulting from data sampling. Two monitoring plots of the association Carduo glaucini–Caricetum tatrorum were totally surveyed 4 times during the studied period. In the first plot located in Zadné Meďodoly, of 25 detected species of higher plants during the study period, 19 species were detected in each survey. Four species, Hieracium villosum, Gentianella lutescens, Polygala brachyptera, and Galium anisophyllum found in 1986, absented in 1996. In the second plot sited near the Bujačí peak, of 20 species found during the studied period, 13 species were detected in each survey. Three species, Carduus glaucinus, Pedicularis verticillata, and Carlina acaulis found in 1986, absented in 1996. Biomass production was estimated on 78.5–118.2 g/m²/year. Similarly, reduction of species richness was also found in the monitoring plots of the association Saxifrago caesiae–Caricetum firmae. Of 17 species of higher plants detected during the study period, 12 species was found in each survey in the first plot. Only one species, Cherleria sedoides, absented and one, Minuartia gerardii, was new for the community. In the second plot located in the Bujačí peak, of 22 species of higher plants found during the study period, 13 species were detected in each survey. Five species, Biscutella austriaca, Salix alpina, Galium anisophyllum, Tofieldia pusilla, and Campanula alpina, disappeared after 11 years. Only Larix decidua was new in the community. Biomass production varied between 147.6–172.5 g/m²/year. In the monitoring plot of the association Saxifrago caesiae–Caricetum firmae located on the tourist trail, abundance of higher plants dropped from 550 ind. of 14 species to 421 ind. of 13 species due to trampling. The highest abundance, 812 ind., was found in 1988. In total, 21 species of higher plants were detected during the studied period. The strongest decline showed Arenaria tenella, less Poa alpina. In opposite, Bistorta vivipara, Carex firma, and Festuca versicolor showed higher abundance in the latter period. Total abundance of the community continued to decline since 1991. In 1997, it reached only 48.1 % of the maximum total community abundance found during the studied period. The results may indicate increased intensity of trampling in the Vysoké Tatry Mts.