Risch Anita Christina

Effects of different sized herbivores on aboveground biomass in Swiss subalpine grasslands

Project Number: CH-4658
Project Type: Master
Project Duration: 02/01/2011 - 12/31/2011 project completed
Funding Source: other ,
Project Leader: Prof. Anita Christina Risch
Head of Animal Ecology
Ökologie der Lebensgemeinschaften
Zürcherstrasse 111
8903 Birmensdorf
Phone: ; +41 (0) 44 739 21 11
FAX: +41 (0) 44 739 22 15
e-Mail: anita.risch(at)wsl.ch

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Herbivores are known to affect grassland properties such as soil characteristics, plant composition or vegetation biomass through grazing, trampling and nutrient reallocation. Consequently, herbivores can alter quality and quantity of forage resources. They can, for example, decrease biomass or improve forage quality. So far, research on how herbivores influence biomass has delivered contrasting results. It has been suggested that ecosystem productivity, as well as grazing intensity, influence how herbivores affect vegetation. Grazing intensity correlates with body size, with larger herbivores consuming more plant biomass. In this study we analyzed the impact of four different sized herbivore groups on aboveground plant biomass using an exclosure set-up in Swiss subalpine grasslands of differing productivity (nutrient-rich short-grass and nutrient-poor tall-grass). We subsequently excluded ungulates, marmots and hares, small sized mammals and insects and determined aboveground plant biomass using canopy intercept method. We found that exclusion of ungulates as well as of insects resulted in an increase of plant biomass in nutrient-rich short-grass. The exclusion of marmots and hares and small sized mammals did not result in an additional increase of plant biomass. In nutrient-poor tall-grass no effects of herbivores on biomass were found. Our results demonstrate that ecosystem productivity, as well as different herbivore species, can determine herbivore influence on the vegetation.

Mirjam von Rütte, 2011: Effects of different sized herbivores on aboveground biomass in Swiss subalpine grasslands. Master thesis ETH Zurich.
pdf Masterthesis

Last update: 7/18/17
Source of data: ProClim- Research InfoSystem (1993-2020)
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