Green alder (Alnus viridis) is a shrub species that has expanded over former pastures
in Central Europe due to land abandonment, leading to negative agri-environmental
impacts, such as a reduction in forage yield and quality and an increase in nitrate
leaching. Robust livestock breeds such as Highland cattle could be used to control
A. viridis encroachment. The objectives of this study were to investigate the impact
of A. viridis encroachment on plant community composition and diversity and to map
the spatial distribution of Highland cattle in A. viridis-encroached pastures. During the
summer of 2019, three different Highland cattle herds were placed along an A. viridis
encroachment gradient. A total of 58 botanical surveys were carried out before grazing
to assess plant community composition, pastoral value, and ecological indicator values.
The spatial distribution of cattle was studied during the whole grazing period by
monitoring six to eight cows equipped with GPS collars in each herd. Plant species
associated with higher pastoral values of the vegetation were found in areas with lower
A. viridis cover, while highly encroached areas were dominated by a few nitrophilus
and shade-tolerant broad-leaved species and by ferns. Cattle spent more time in areas
with higher pastoral value but did not avoid areas with high cover of A. viridis, on
steep slopes or far from water. These results show that Highland cattle are able to
tolerate harsh environmental conditions and that they can exploit A. viridis-encroached
pastures. This suggests that they have a high potential to reduce A. viridis encroachment
in the long-term.