Indicators for assessing the multifunctionality of agriculturally used grasslands

• In grasslands, many ecosystem services (ES) are correlated with each other. • Correlations among ES result in two distinct ES-indicator bundles. • Non-production multifunctionality summarizes all ES of primarily public relevance. • Plant diversity is a suitable indicator for non-production multifunctionality. • In contrast, fertilization intensity is a strong negative indicator of this metric. Grasslands are highly multifunctional ecosystems, providing forage to livestock and many regulating and cultural ecosystem services (ES). Agri-environmental schemes (AES) often aim at sustaining and increasing especially non-production ES, i.e., those services not primarily relevant for production but for society as a whole. An open question restricting the implementation of such AES for grassland ES multifunctionality is how to effectively measure and monitor multifunctionality without separately accounting for all single ES. To address this question, we measured 30 plot-level ES indicators, including plant species richness, in 88 permanent grasslands along a fertilization intensity gradient in Switzerland. We explored the correlative structure among all ES indicators and the potential of each indicator to approximate non-production ES multifunctionality. We finally discuss potentially suitable ES-multifunctionality indicators for future result-based AES. The analyses revealed two distinct bundles within the comprehensive list of ES indicators considered in the study. The first bundle consisted of ten ES indicators, including aesthetic appreciation, fungal richness, plant richness, and several ES indicators for reduced adverse environmental impacts (e.g., lower nutrient leaching risk). This bundle was strongly negatively related to the second bundle, composed of twelve ES indicators that were mostly directly related to intensive forage production (e.g., nutrient supply, yield quantity and yield quality). Plant species richness (positive) and fertilization intensity (negative) were the two measures most closely related to non-production multifunctionality, highlighting their potential to be put to use as multifunctionality indicators. We argue that due to the policy relevance of biodiversity conservation, plant species richness could find application as indicator for AES designed to increase and monitor grassland non-production multifunctionality. While plant species richness is rather stable over time, considering changes (reductions) in fertilization intensity could be an option for a more responsive indicator to be used to facilitate ES-positive grassland management on the short term. Integrating our findings in future agricultural policies could be a significant step towards rewarding land users for the non-production benefits provided by their agroecosystems.