Review Mycorrhizal networks: Mechanisms, ecology and modelling Suzanne W. SIMARD a, *, Kevin J. BEILER b , Marcus A. BINGHAM a , Julie R. DESLIPPE c , Leanne J. PHILIP d , Franc ¸ois P. TESTE e a Department of Forest Sciences, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia, Canada V6T 1Z4 b Biology Faculty, University of British Columbia Okanagan, 3333 University Way, Kelowna, British Columbia, Canada V1V 1V7 c Ecosystems and Global Change, Landcare Research, Riddet Road, Massey University Campus, Palmerston North 4442, New Zealand d Biology/Environmental Studies, Saint Mary’s University, Halifax, Nova Scotia, Canada B3H 3C3 e School of Plant Biology, Faculty of Natural and Agricultural Sciences, The University of Western Australia, Crawley WA 6009, Australia article info Article history: Received 3 November 2011 Received in revised form 22 January 2012 Accepted 31 January 2012 Keywords: Ascomycota Basidiomycota Carbon transfer Complex adaptive systems Diversity Evolution Glomeromycota Mycoheterotrophy Stability abstract Mycorrhizal networks, defined as a common mycorrhizal mycelium linking the roots of at least two plants, occur in all major terrestrial ecosystems. This review discusses the recent progress and challenges in our understanding of the characteristics, functions, ecology and models of mycorrhizal networks, with the goal of encouraging future research to improve our understanding of their ecology, adaptability and evolution. We focus on four themes in the recent literature: (1) the physical, physiological and molecular evidence for the exis- tence of mycorrhizal networks, as well as the genetic characteristics and topology of networks in natural ecosystems; (2) the types, amounts and mechanisms of interplant material transfer (including carbon, nutrients, water, defence signals and allelochemicals) in autotrophic, mycoheterotrophic or partial mycoheterotrophic plants, with particular focus on carbon transfer; (3) the influence of mycorrhizal networks on plant establishment, survival and growth, and the implications for community diversity or stability in response to environmental stress; and (4) insights into emerging methods for modelling the spatial configuration and temporal dynamics of mycorrhizal networks, including the inclusion of mycorrhizal networks in conceptual models of complex adaptive systems. We suggest that mycorrhizal networks are fundamental agents of complex adaptive systems (ecosystems) because they provide avenues for feedbacks and cross-scale interactions that lead to self- organization and emergent properties in ecosystems. We have found that research in the genetics of mycorrhizal networks has accelerated rapidly in the past 5 y with increasing resolution and throughput of molecular tools, but there still remains a large gap between understanding genes and understanding the physiology, ecology and evolution of mycor- rhizal networks in our changing environment. There is now enormous and exciting poten- tial for mycorrhizal researchers to address these higher level questions and thus inform ecosystem and evolutionary research more broadly. ª 2012 The British Mycological Society. Published by Elsevier Ltd. All rights reserved. * Corresponding author. Tel.: þ1 604 822 1955; fax: þ1 604 822 9102. E-mail addresses: suzanne.simard@ubc.ca (S. W. Simard), kjbeiler@interchange.ubc.ca (K. J. Beiler), binghm@interchange.ubc.ca (M. A. Bingham), DeslippeJ@landcareresearch.co.nz (J. R. Deslippe), Leanne.Philip@SMU.CA (L. J. Philip), francois.teste@uwa.edu.au (F. P. Teste). journal homepage: www.elsevier.com/locate/fbr fungal biology reviews 26 (2012) 39 e60 1749-4613/$ e see front matter ª 2012 The British Mycological Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.fbr.2012.01.001