20% loss of unimproved farmland in 22 years in the Engadin, Swiss Alps

• Large loss of low-nutrient grassland over 22 years in an extant hotspot for agro-biodiversity.
• Strong negative effects on biodiversity of “amelioration” projects indicated.
• Preservation of fertile meadows used at low intensity (valuable for biodiversity; some extensification); large interchange with fertile meadows of high intensity.
• Relevant data from a comparably large area for the further development of agro-policies.
• Overall moderate abandonment, but affecting mainly parcels of high value for biodiversity.

Agricultural intensification has reached mountain areas with retardation. This development is worrying as it targets some of the last remaining strongholds of traditionally farmed land in central Europe which are important hotspots of biodiversity. However, large-scale documentations of changes in agricultural habitats are rare, but are needed to guide agricultural policy for the conservation of biodiversity.We investigated vegetation changes of the agricultural landscape in a valley of the Alps (Engadin, a rather dry valley in Switzerland) between 1987/1988 and 2009/2010. In 58 plots (total area 1253 ha) we recorded changes in vegetation types and the intensity of usage and we investigated correlations between these changes and site factors.By 2009/2010, all unimproved vegetation types have lost 20% of the area they covered in 1987/1988. The loss was greatest in areas where new agricultural infrastructure/reallocation projects (“ameliorations”) had been realized. This observation illustrates the potentially devastating effect of such projects for farmland biodiversity.Overall, intensively used fertile meadows (which are of limited nature value) have increased. The afflux came from the above mentioned unimproved grassland types, and not, as might be expected, from low-intensity fertile meadows (traditional hay meadows with a high nature value). In fact, the latter meadow type has seen a net gain from the intensively used fertile meadows (i.e. extensification). Both of these opposing processes (intensification and extensification) were subsidized by the government: money for infrastructure projects on the one hand and money for ecological compensation areas on the other hand.Abandonment of farmland, unlike in some other regions in the Alps, is not a general problem in the Engadin, but it did reduce the area of xerotherm grassland by 19% and of nutrient-poor meadows by 8%. Grazing, which could prevent abandonment, increased during our study period, but was mostly of high intensity, thus was not optimal from a conservation point of view. Recent contracts for nature conservation are likely to help maintain mowing and extensive grazing management on marginal land.The Engadin remains a biological hotspot and a beautiful landscape of high value for tourism. But these values are not secured as illustrated by the loss during the last 20 years. Thus, planers of irrigation and other infrastructure projects and decision-makers in general need to better incorporate both the extant nature values and their fragility into their planning.