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Influence of increasing grazing pressure on
species richness in subalpine grassland in the Swiss National Park
Martin Schütz, Thomas Wohlgemuth, Gérald Achermann, Bertil O. Krüsi, Helena GrämigerSwiss Federal Research Institute WSL, CH-8903 Birmensdorf, SwitzerlandAbstractThe development of both the ungulate populations and the vegetation have been monitored since the Swiss National Park was founded.The analysis of these basic data has revealed a highly significant positive correlation between the increase in the number of red deer and the number of phanerogam species in those parts of the subalpine pastures that are intensively grazed by red deer. These observations apply regardless of the size of the permanent plots, which varies from 1 sqm to 3055 sqm. The connection between the increase in species richness since the Park was founded and the rising numbers of red deer is most evident in former tall-herb communities (Rumicetum alpini) and golden oat-grass meadows (Trisetetum flavescentis) In former red fescue pastures (Crepido-Festucetum nigrescentis)the same trend is evident, though less pronounced. The different developmental paths depend on the initial situation, which was determined by how the land was used agriculturally before the National Park was founded and also by the nutrient gradient. It seems very likely that there is a direct, causal relationship between the increase in species diversity on nutrient-rich permanent plots and the increase in grazing intensity, i.e. the rise in the numbers of red deer in the Park. These observations provide confirmation for the 'intermediate disturbance hypothesis' for the subalpine pastures in the Swiss National Park. Preface | abstract 1 | abstract 2 | abstract 3 | abstract 4 | abstract 5 | abstract 6 | abstract 7 | abstract 8 | abstract 9 | abstract 10 | abstract 11 |