Grazing and light modify Silene latifolia responses to nutrients and future climate

RESEARCH ARTICLE Grazing and light modify Silene latifolia responses to nutrients and future climate Maria-Theresa JessenID1,2,3*, Harald Auge1,2, W. Stan Harpole1,3,4, Yann Hautier5, Anu Eskelinen1,3,6 1 German Centre for Integrative Biodiversity Research–iDiv Halle-Jena-Leipzig, Leipzig, Germany, 2 Department of Community Ecology, Helmholtz Centre for Environmental Research—UFZ, Halle, Germany, 3 Department of Physiological Diversity, Helmholtz Centre for Environmental Research–UFZ, Leipzig, Germany, 4 Martin Luther University Halle-Wittenberg, Halle (Saale), Germany, 5 Department of Biology, Ecology and Biodiversity Group, Utrecht University, Utrecht, The Netherlands, 6 Department of Ecology and Genetics, University of Oulu, Oulu, Finland * maria-theresa.jessen@ufz.de Abstract Altered climate, nutrient enrichment and changes in grazing patterns are important environ- mental and biotic changes in temperate grassland systems. Singly and in concert these fac- tors can influence plant performance and traits, with consequences for species competitive ability, and thus for species coexistence, community composition and diversity. However, we lack experimental tests of the mechanisms, such as competition for light, driving plant performance and traits under nutrient enrichment, grazer exclusion and future climate. We used transplants of Silene latifolia, a widespread grassland forb in Europe, to study plant responses to interactions among climate, nutrients, grazing and light. We recorded trans-

plant biomass, height, specific leaf area (SLA) and foliar carbon to nitrogen ratio (C:N) in full-factorial combinations of future climate treatment, fertilization, grazer exclusion and light addition via LED-lamps. Future climate and fertilization together increased transplant height but only in unlighted plots. Light addition increased SLA in ambient climate, and decreased C:N in unfertilized plots. Further, transplants had higher biomass in future climatic conditions when protected from grazers. In general, grazing had a strong negative effect on all mea- sured variables regardless of added nutrients and light. Our results show that competition for light may lead to taller individuals and interacts with climate and nutrients to affect traits related to resource-use. Furthermore, our study suggests grazing may counteract the bene- fits of future climate on the biomass of species such as Silene latifolia. Consequently, graz- ers and light may be important modulators of individual plant performance and traits under nutrient enrichment and future climatic conditions. Introduction Grasslands are increasingly exposed to concurrent impacts of climate change, nutrient enrich- ment and changes in grazing practices [1]. Singly and in concert these global change drivers can affect plant community composition and diversity [2–4]. In a changing environment, PLOS ONE PLOS ONE | https://doi.org/10.1371/journal.pone.0276789 November 8, 2022 1 / 16 a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS Citation: Jessen M-T, Auge H, Harpole WS, Hautier

Y, Eskelinen A (2022) Grazing and light modify Silene latifolia responses to nutrients and future climate. PLoS ONE 17(11): e0276789. https://doi. org/10.1371/journal.pone.0276789 Editor: Mai-He Li, Eidgenossische Forschungsanstalt fur Wald Schnee und Landschaft Institut fur Schnee- und Lawinenforschung, SWITZERLAND Received: March 4, 2022 Accepted: October 14, 2022 Published: November 8, 2022 Peer Review History: PLOS recognizes the benefits of transparency in the peer review process; therefore, we enable the publication of all of the content of peer review and author responses alongside final, published articles. The editorial history of this article is available here: https://doi.org/10.1371/journal.pone.0276789 Copyright: © 2022 Jessen et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: The data are available in Figshare under the following DOI https://doi.org/ 10.6084/m9.figshare.21369714.v1.