Veränderung der Schweizer Moorvegetation innerhalb von fünf Jahren

Abstract

To assess whether short-term changes in mire vegetation can be detected using the phytosociological approach, paired vegetation relevés from two surveys of 112 mire sites of Switzerland were assigned to phytosociological alliances through a numerical approach. About 30% of the plots were assigned to different alliances in the two surveys. These transitions were analysed based on species frequencies and interpreted ecologically using Landolt's indicator values. Transitions between different alliances were more frequently related to the appearance of new species rather than to the disappearance of species. Transitions from and to peat bog communities were frequent. Many plots with fen vegetation were transformed into other wetland types. Fen-grassland increased in abundance, mainly at the cost of small-sedge fens. To reestablish the function of the Swiss mires as peat producers, we recommend to raise the mean summer water table to a maximum depth of 10 cm.

Monitoring Concept of Climate-Induced Impacts on Peat Bog Vegetation in Pokljuka Plateau in Triglav National Park, Slovenia

“…According to the results of other studies on peatbog and fen vegetation (Dakskobler et al 2011;Graf et al 2010) the occurrence of different plant species seems to be a good indicator for detecting early environmental changes. Earliest changes will be most probably detected according to the composition of different Sphagnum species, species abundances, the decrease of indicator species for low temperature, high humidity, low pH and low nutrient value (Table 11.1), the increase of generalists and of species which are characteristic for more dry habitats at the cost of peatbog specialists.…”

“…With water contents around 90 % (Parish et al 2008), hydrological regimes are the fundamental component of peatlands. For the appropriate functioning of mires and fens, an increase of mean summer water levels to maximum depths of about 10 cm are necessary (Graf et al 2010). At this level, fens start to produce peat during the summer months, whereas they loose peat if the water table is lower (Blankenburg et al 2001cited in Graf et al 2010).…”

Recent changes in the plant composition of wetlands in the Jura Mountains

“…Eutrophication is a serious threat to these wetlands and fens, especially oligotrophic and acidic fens ( Caricion fuscae ). Eutrophication has been repeatedly observed to be a serious problem with a substantial negative impact on many European habitats, such as wetlands (Bollens et al., ; Graf et al., ; Kapfer, Grytnes, Gunnarsson, & Birks, ), oligotrophic meadows (Diekmann et al., ; Mauchamp, ) and alluvial forests (Gallandat, Gobat, & Roulier, ). Hence, although legally protected and managed for conservation goals, the quality of these wetlands is still decreasing, with a loss of diversity, especially in typical species.…”

“…Vegetation changes in wet ecosystems have been studied in most Central European countries, e.g. in Switzerland (Bergamini & Pauli, ; Graf, Wildi, Küchler, & Ecker, ; Klaus, ), the Netherlands (ter Braak & Wiertz, ) and France (Bailly, Ferrez, Guyonneau, & Schaefer, ; Guyonneau, ), as in Northern Europe (e.g. Gunnarsson, Malmer, & Rydin, in Sweden).…”

“…More precisely, warmer and drier conditions accelerate organic matter mineralization, which releases supplementary nutrients (eutrophication) and, consequently, modifies species composition, particularly in nutrient‐poor fens. Taller, more competitive species colonize the wetlands, resulting in less available light at soil level (Bergamini et al., ; Graf et al., ; Pauli et al., ). Altogether, these drier, darker and more eutrophic conditions lead to a decrease in the frequency and cover of the typical vascular plants and bryophytes of wetlands (Gough, Osenberg, Gross, & Collins, ; Morecroft, Sellers, & Lee, ).…”