Agradecimentos: The authors thank the managers of the Schwäbische Alb Exploratory, Swen Renner, Kirsten Reichel-Jung, Iris Steitz, Sandra Weithmann, Florian Staub and all former managers for their work in maintaining the plot and project infrastructure; Christiane Fischer, Jule Mangels and Victoria Grießmeier for giving support through the central office, Michael Owonibi and Andreas Ostrowski for managing the central database, and Markus Fischer, Eduard Linsenmair, Dominik Hessenmöller, Daniel Prati, Ingo Schöning, François Buscot, Ernst-Detlef Schulze, Wolfgang W. Weisser and the late Elisabeth Kalko for their role in setting up the Biodiversity Exploratories project. The authors thank the administration of the UNESCO Biosphere Reserve Swabian Alb as well as all landowners for the excellent collaboration. The authors thank Sabine Rudolph and Heike Haslwimmer, for the technical support in the laboratory as well as Ines Binder, Kamen Yurukov and Kathinka Lang for the previous soil laboratory analyses. The authors would also like to thank Beartix Schnabel and Melanie Gawlich (Department of Soil Ecology – UFZ); Ina Geier and Martina Herrmann (Department of Community Ecology – UFZ) for their support during NGS library preparation and sequencing. The authors further thank Deborah Schäfer and Judith Hinderling for their help during experimental setup and vegetation records, and Hugo Saiz for his support with SEM interpretation. The work has been (partly) funded by the DFG Priority Program 1374 ‘Infrastructure-Biodiversity-Exploratories’ (KA 1590/8-2, KA 1590/8-3, MA 4436/1-4, WU 614/2-2) and was also financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001 – process 88881.172163/2018-01 fellowship to AA. Fieldwork permits were issued by the responsible state environmental office of Baden-Württemberg. Open Access funding enabled and organized by Projekt DEAL Ver menos

Abstract: Plant-soil feedbacks (PSFs) underlying grassland plant richness and productivity are typically coupled with nutrient availability; however, we lack understanding of how restoration measures to increase plant diversity might affect PSFs. We examined the roles of sward disturbance, seed addition and land-use intensity (LUI) on PSFs. We conducted a disturbance and seed addition experiment in 10 grasslands along a LUI gradient and characterized plant biomass and richness, soil microbial biomass, community composition and enzyme activities. Greater plant biomass at high LUI was related to a decrease in the fungal to bacterial ratios, indicating highly productive grasslands to be dominated by bacteria. Lower enzyme activity per microbial biomass at high plant species richness indicated a slower carbon (C) cycling. The relative abundance of fungal saprotrophs decreased, while pathogens increased with LUI and disturbance. Both fungal guilds were negatively associated with plant richness, indicating the mechanisms underlying PSFs depended on LUI. We show that LUI and disturbance affect fungal functional composition, which may feedback on plant species richness by impeding the establishment of pathogen-sensitive species. Therefore, we highlight the need to integrate LUI including its effects on PSFs when planning for practices that aim to optimize plant diversity and productivity Ver menos