Contents lists available at ScienceDirect Biological Conservation journal homepage: www.elsevier.com/locate/biocon A new method for jointly assessing effects of climate change and nitrogen deposition on habitats Anna Ida Hämmerle a, ⁎ , Johannes Wessely a , Undrakh-Od Baatar a , Franz Essl a , Dietmar Moser a , Borja Jiménez-Alfaro b , Ute Jandt c , Emiliano Agrillo d , Zvjezdana Stančić e , Thomas Dirnböck f , Stefan Dullinger a a Division of Conservation Biology, Vegetation- and Landscape Ecology, Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, Vienna 1030, Austria b German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103 Leipzig, Germany c Department of Geobotany and Botanical Garden, Martin Luther University Halle-Wittenberg, Kirchtor 1, 06108 Halle, Germany d Department of Environmental Biology, “Sapienza”, University of Roma, Botanical Garden, Largo Cristina di Svezia 24, 00165 Roma, Italy e Faculty of Geotechnical Engineering, University of Zagreb, Hallerova aleja 7, 42000 Varaždin, Croatia f Department for Ecosystem Research and Environmental Information Management, Environment Agency Austria, Spittelauer Lände 5, A-1090 Vienna, Austria ARTICLE INFO Keywords: Climate change Habitats N deposition Projections Risk assessment Species distribution models Synergistic effects 1. Introduction Biodiversity is under pressure globally from multiple drivers in- cluding land use change, overexploitation, climate change, atmospheric nitrogen (N) deposition, and other environmental stressors (Ceballos et al., 2015; Sala et al., 2000). Concern about the decline of biodiversity under these multiple threats and the consequences for ecosystem functioning and services has motivated considerable research effort (e.g. Barnosky et al., 2011; Bellard et al., 2012; Estes et al., 2011; Tittensor et al., 2014) as well as internationally coordinated policy response (e.g. Convention on Biological Diversity, Intergovernmental Platform for Biodiversity & Ecosystem Services). Scenarios and projec- tions of how biodiversity may change under plausible future pathways of drivers are key to proactive environmental policies and management (e.g. Guiot and Cramer, 2016; Pereira et al., 2010; Thuiller et al., 2013). A shortcoming of most of these projections is, however, that they ex- clusively consider one particular driver and neglect the simultaneous and possibly interacting effects of others (e.g. Pereira et al., 2010; Titeux et al., 2016). Climate change and N deposition represent a pair of drivers that is known to have separate and interactive effects on biodiversity and ecosystems (Bernhardt-Römermann et al., 2015; Greaver et al., 2016; Porter et al., 2013). Adverse effects of N deposition mainly stem from eutrophication, which fosters the growth of opportunistic plant species and, eventually, the exclusion of less competitive ones (Bobbink et al., 2010a, 2010b; Gilliam, 2006; Hautier et al., 2009; McClean et al., 2011), and from acidification, which leads to cation imbalances, asso- ciated physiological stresses and loss of sensitive plant species from communities (Roem et al., 2002; Simkin et al., 2016a; Stevens et al., 2010). Both of these effects can propagate through the food web and alter the composition and diversity of heterotrophic groups (de Sassi et al., 2012; Wallisdevries and Van Swaay, 2006). Climate change may modify N supply to biota by influencing atmospheric N deposition through the amount and temporal pattern of precipitation, which in turn leads to modifications in soil chemical and microbial processes. Moreover, temperature and moisture conditions control the availability of soil N for plants via their effects on microbial transformation rates of reactive N (Butler et al., 2012; Guntiñas et al., 2012). Interactions are complex and only partly understood (Greaver et al., 2016), but both empirical observations and modelling studies indicate that a warmer https://doi.org/10.1016/j.biocon.2018.09.014 Received 9 February 2018; Received in revised form 20 August 2018; Accepted 8 September 2018 ⁎ Corresponding author. E-mail addresses: annahaemmerle@hotmail.com (A.I. Hämmerle), stefan.dullinger@univie.ac.at (S. Dullinger). Biological Conservation 228 (2018) 52–61 0006-3207/ © 2018 Elsevier Ltd. All rights reserved. T