Long-term effects of grazing on subalpine and alpine grasslands in the Central Alps, Austria

The effects of grazing exclusion on species diversity and functional diversity were analyzed along an elevation gradient from the subalpine (1960 m a.s.l) to the lower and upper alpine zone (2275 in-2650 m a.s.l) in the Austrian Central Alps for 15 years. Nine sites were chosen, including grasslands at different elevations, a bog and a glacier foreland site at the lower alpine zone and a snowbed at the upper alpine zone. Data were acquired by frequency counts in 1 m(2) permanent plots inside each fenced area (three plots per site) and outside in grazed areas (three plots), Diversity indices and functional diversity were analyzed by means of generalized linear mixed models (GLMMs), Exclosure, duration of exclusion and exclosureyears (interaction effect) were defined as predictor variables, Multivariate ordination techniques were used to (i) determine species responses to grazing exclusion (pRDA, partial redundancy analysis) and (ii) to create a distance matrix representing the changes between exclosures and control plots per year (NMDS, non-metric multidimensional scaling). At the subalpine grassland, first differences between exclosure and control plots occurred already only after three years, at the upper alpine zone after four and five years. Contrary to our expectation, dwarf shrubs did not increase within the exclosures of the subalpine grassland. Instead, mainly the tall forb Geranium sylvaticuin increased. Species richness significantly decreased at the exclosures of the subalpine zone, the snowbed and at one upper alpine grassland sites. The communities of the glacier foreland and the hog were hardly affected by grazing exclusion. We conclude that plant species and communities react individually depending on elevation and grazing animals. Grazi exclusion studies at high elevations should definitely be carried out in the long-term, (C) 2017 Gesellschaft lift. Okologie. Published by Elsevier GmbH. All rights reserved,