J Veg Sci. 2018;1–9. wileyonlinelibraryџcomjournaljvs | 1 Journal of Vegetation Science © 2018 International Association for Vegetation Science Received 8 August  | Accepted 6 January 8 DOI џjvsџ66 RESEARCH ARTICLE The importance of facilitative interactions on the performance of Colobanthus quitensis in an Antarctic tundra Lohengrin A. Cavieres 1,2 | Mercedes Vivas 1,3 | Maritza A. K. Mihoc 1,2 | Diana A. Osses 1,2 | José M. Ortiz-Gutiérrez 1,2 | Patricia L. Saéz 4 | León A. Bravo 3 1 Departamento de Botánica Facultad de Ciencias Naturales y Oceanográficas Universidad de Concepción Concepción Chile 2 Instituto de Ecología y Biodiversidad IEB Santiago Chile 3 Laboratorio de Fisiología y Biología Molecular Vegetal Instituto de Agroindustria Departamento de Ciencias Agronómicas y Recursos Naturales Facultad de Ciencias Agropecuarias y Forestales Center of Plant Soil Interaction and Natural Resources Biotechnology Scientific and Technological Bioresource Nucleus Universidad de La Frontera Temuco Chile 4 Laboratorio Cultivo de Tejidos Vegetales Centro de Biotecnología Departamento de Silvicultura Facultad de Ciencias Forestales Universidad de Concepción Concepción Chile Correspondence Lohengrin Aџ Cavieres Departamento de Botánica Facultad de Ciencias Naturales y Oceanográficas Universidad de Concepción Concepción Chileџ Email: lcaviere@udec.cl Funding information CONICYT GrantAward Number PIAART  Institute of Ecology and Biodiversity IEB Coordinating Editor Richard Michalet Abstract Aims The sign of interactions among plants in very harsh environments is under debateџ The Antarctic tundra is one of the harshest environments on Earth and only two vascular plants Deschampsia antarctica and Colobanthus quitensis have success fully established natural populationsџ D. antarctica mostly establishes facilitative in teractions with other species mosses but there is no information about the interspecific interactions established by C. quitensisџ We assessed whether C. quiten- sis grows frequently associated with D. antarctica and if D. antarctica neighbours have a positive effect on the survival growth and photochemical efficiency of C. quitensis individuals. Location King George Island Antarctic Peninsulaџ Methods To assess the spatial association among the two Antarctic vascular plants fifty  m   cm quadrats were sampled on each of four different substrates moss carpet areas dead moss carpet areas dominated by D. antarctica; a transition zone between dead moss carpets and fellfields and fellfields characterized by very poor vegetation coverџ Infrared thermal images were taken to estimate whether growth associated with D. antarctica affected the foliar temperature of C. quitensisџ The im portance of D. antarctica neighbours on the growth survival and photochemical ef ficiency of C. quitensis was evaluated with a neighbour removal experimentџ Results The number of C. quitensis individuals associated with D. antarctica was sig nificantly higher than when growing alone in the moss carpet and the dead moss carpet while in the transition zone there was a trend in that directionџ C. quitensis individuals growing associated with D. antarctica were bigger than those growing alone in these three substrate typesџ In the fellfield site there were no significant dif ferences neither in the number nor the size of individuals when growing alone or associated with D. antarctica. Foliar temperature of C. quitensis individuals associated with D. antarctica was slightly џC but significantly higher than in those growing aloneџ The growth survival and photochemical efficiency of C. quitensis individuals with neighbours were higher than in individuals with neighbours removedџ Conclusions Our results indicate that D. antarctica has a facilitative effect on the growth survival and photochemical efficiency of C. quitensisџ Thus facilitative inter actions are present and are important in one of the harshest environments on Earth although results from the fellfield site indicate that further research is neededџ