Biodiversity impact assessment of grazing sheep

Abstract

Biodiversity is a complex and intangible field and a general applicable quantification methodology is yet to be established. Neither indicator systems on the influence on species richness or ecosystem services nor the assessment of the amount of human influence lead to a reliable quantification method. A new approach developed by Lindner in 2016 assesses the difference between a reference situation with the current situation through land use by combining expert knowledge with fuzzy logic and constructing trajectories of biodiversity impacts of case-specific indicator categories through interviews with a group of specialists. In this paper, the method is adjusted for the evaluation of the biodiversity impact of grazing sheep. A set of indicators was constructed, weighted and individually assessed together with sheep farming experts. The established indicators include the change of biodiversity through grazing sheep, the optimal grazed area, the optimal grazing period, the influences on the soil and the humus layer, the impact of machinery use, the importance of transhumance as well as the influence of other species like goats within the herd. An extensive sheep farm from the Swabian Alb, Germany and a semi-extensive sheep farm from the Rhön Mountains, Germany, were assessed for exemplarily testing the method. The assessment presented results assigning the more extensive sheep farm a higher biological as it was excepted. The set of indicators appears applicable for similar farms in similar regions. A point of further inquiry is to underline positive effects and benefits of grazing sheep on biodiversity observed in other studies.