Assessing the adaptability of fodder trees in agroforestry under varied climates to meet farmers' expectations in Western Switzerland

Agroforestry in Switzerland could be a promising solution to provide additional forage, especially during summer, when risks of drought-induced decrease in forage production are the highest. One important factor to study is the survival and adaptation of fodder tree species to different altitudes and climatic conditions, especially in Switzerland where hedgerow systems have been tested so far. This work aimed to assess the survival and adaptability of five fodder tree species (Morus alba, Tilia, Fraxinus ornus, Salix caprea, Alnus cordata) planted in hedgerows in six sites along an altitudinal and climatic gradient to meet farmers' expectations in Western Switzerland. First, we interviewed the participants and found that the main motivations of the farmers were climate resilience, research purpose and animal welfare. Moreover, the scientific results provided by Agroscope as well as being part of a group and the maintenance on-site were identified as levers. Aridity in sites during the growing season 2022 (April-August) significantly led to higher tree mortality rates (with an exception for Salix caprea) with Fraxinus ornus (23 %) < Morus alba (29 %) < Tilia (39 %) < Alnus cordata (75 %) < Salix caprea (83 %). We then confirmed that fodder tree species can become a great alternative to grass-based forage in early summer with significantly good digestibility (high SLA and low LDMC). However, further attention should be paid to the adaptation along a climatic gradient in Switzerland as we found a significant effect of sites in 2023 on the net photosynthetic activity and total leaf area.