Forest grazing - a debatable Alpine land use

Do grazing cattle impair the regeneration of subalpine forests?

Collection of representative forage samples

In the Alps, the multipurpose utilisation of agricultural and forest resources has a long tradition. Twelve per cent of the mountain forests in Switzerland are grazed by domestic animals, mainly by cattle. In many other regions, the (re-) introduction of silvopastoral systems is discussed. However, the parties in favour of alpine natural forests consider forest grazing a detrimental form of land use and want to restrict it.

Subalpine mountain forests often serve as protection against natural hazards (e.g. avalanches), in addition to timber production. Domestic animals grazing on mosaics of coniferous forests and open pastures are considered hindering tree regeneration, reducing timber quality and impairing the protective function of mountain forests. The influence of cattle grazing on the dynamic of sub-alpine forests has been the subject of lively debates across the past decades but there have been few scientific studies to substantiate the various opinions, and thus controversial views continue to be held until today.

An interdisciplinary approach

In order to verify the various prejudices to forest grazing, in May 2000 the SLF started comparative field studies and experiments on the effects of grazing cattle on regeneration and structure of sub-alpine forests. The results of the project will serve as a basis for generating strategies for the sustainable management of Alpine silvopastoral systems. Damages caused by cattle are assessed comparing the condition of young trees immediately before and after grazing. We use dendroecology (tree ring analysis) to investigate the long term influence of grazing on forest structure and timber quality. Browsing of different herbage plant species is recorded on systematically selected plots. With the double alkane technique including daily collection of herbage and faeces spot samples, we measure the digestibility of the herbage selected.

Forest grazing: better than its reputation?

Preliminary results suggest that young spruces are not damaged severely by grazing cattle if stocking density is low (approx. 1 livestock unit per hectare) and the ranges are sufficiently large, thus enabling the cattle to select among forage plant species. Cattle prefer grass species and are able to select herbage of medium digestibility even if the herbage supply is getting scarce towards the end of the grazing period.

Publications

• List of Publications of Dr. Andrea Corinna Mayer

Participants

The project is part of PRIMALP at ETH Zurich and is realised in close collaboration with the Institute for Landscape Management of the Albert-Ludwigs-University of Freiburg, Germany and the Institute of Animal Sciences, Animal Nutrition, ETH Zurich.

Contact

• Peter Bebi