| Abstrakt: |
Abstract: a_1Alpine vegetation is considered to be particularly sensitive to climate changes. Here we document changes in species richness, distribution and composition over the past 50 years by resurveying vegetation in Rondane, a well-studied alpine area in central Norway. We estimated changes in species occurrences, species richness and species’ realized optima to study relationships between vegetational and environmental change. We used a weighted average approach with elevation and indicator values for light, temperature, pH, moisture, nutrients and tolerance to snow-cover duration. Permutation tests, allowing for unequal sampling in the original survey and the resurvey, indicated whether vegetation changes were statistically significant. We found no significant change in the average number of species per plot since 1950. Of 21 species analysed for changes in frequency and realized optimum, ten showed statistically significant changes in frequency (six decreased, four increased), and six exhibited statistically significant changes in their optimum along the soil-pH gradient. Statistically significant optimum changes were found along the nutrient and light gradients (three species) and the elevation and snow-cover gradients (two species). No statistically significant changes were found along the temperature or moisture gradients. In comparison with other studies, our results suggest that recent climate changes have had a relatively low impact on alpine vegetation in the Rondane mountains. |
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