Search

Alnus viridis is a pioneer species that has expanded in Central Europe in the last decades, causing a series of negative agro-environmental impacts. Robust livestock grazing could be used as a targeted tool to reduce its encroachment, but more information is needed to find the best approach to achieve this goal. In this study, we assessed the potential of molasses-based blocks (MB) to lure Highland cattle into A. viridis-encroached areas and monitored impacts on the vegetation after grazing. In 2019 and 2020, two Highland cattle herds equipped with GPS collars were placed in three paddocks in the Swiss and Italian Alps, differing in the degree of A. viridis encroachment. In 2020, MB were added to highly encroached areas within each paddock to attract the herds to feed on A. viridis. Botanical surveys were carried out before and after grazing, around MB and control areas. Highland cattle grazed significantly more around MB (up to 50 m from the MB) compared to the previous year (i.e., same area without MB) and compared to control areas. The increased targeted grazing around MB led to a significant decrease in herbaceous cover and an increase in bare soil compared to control areas. Livestock grazing and trampling significantly reduced the cover of ferns, tall herbs, medium and small herbs, and woody species around MB compared to control areas. A. viridis leaves and branches were significantly removed and damaged up to 10 m from the MB, due to the more intense livestock grazing. Such results highlight the potential of this management regime to effectively reduce A. viridis encroachment in montane grasslands.

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.