Acknowledgements
This work was supported by the National Socio-Environmental Synthesis Center (SESYNC) under funding received from the National Science Foundation (DBI-1052875 and 1119891) and by the Helmholtz Centre for Environmental Research (Research School ESCALATE, VH-KO-613), the German Federal Ministry of Education and Research (GLUES, 01LL0901A), the Martin-Luther-University Halle-Wittenberg and the Synthesis Centre (sDiv) of the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig (DFG FZT 118).