Journal of Biogeography. 2019;00:1–11. wileyonlinelibrary.com/journal/jbi | 1 © 2019 John Wiley & Sons Ltd Received: 14 November 2018 | Revised: 13 August 2019 | Accepted: 23 September 2019 DOI: 10.1111/jbi.13739 RESEARCH PAPER Tropical forest type influences community assembly processes in arbuscular mycorrhizal fungi Camilla Maciel Rabelo Pereira 1,2 | Álvaro López‐García 2 | Danielle Karla Alves da Silva 3 | Leonor Costa Maia 1 | Tobias Guldberg Frøslev 2 | Rasmus Kjøller 2 | Søren Rosendahl 2 1 Programa de Pós‐graduação em Biologia de Fungos, Departmento de Micologia, Universidade Federal de Pernambuco, Recife, Brazil 2 Department of Biology, University of Copenhagen, Copenhagen, Denmark 3 Programa de Pós‐Graduação em Ecologia e Monitoramento Ambiental, Universidade Federal da Paraíba, Rio Tinto, Brazil Correspondence Søren Rosendahl, Department of Biology, Sect. Ecology & Evolution, University of Copenhagen, Copenhagen, Denmark. Email: soerenr@bio.ku.dk Funding information Conselho Nacional de Desenvolvimento Científico e Tecnológico, Grant/Award Number: 140536/2013‐2, 307129/2015‐2 and 446144/2014‐2; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Grant/Award Number: 99999.004036/2015‐08; European Union's Horizon 2020 Marie Curie Individual Fellowship, Grant/Award Number: 708530 Handling Editor: Vincent Merckx Abstract Aim: Plant community assembly in tropical rain forest has been shown to be largely governed by stochastic processes, but as arbuscular mycorrhizal (AM) fungi display limited host preference, they may not follow the same stochastic assembly pattern. Here, we determined the relative importance of environmental and spatial drivers responsible for the community assembly process of AM fungi in two types of tropical rain forest: semideciduous rain forest and dense ombrophilous forests. Location: Atlantic rain forest in north‐eastern Brazil, South America. Taxon: Arbuscular mycorrhizal fungi (Glomeromycotina). Methods: We collected root samples from eight protected areas of Atlantic forest along a 700 km transect in north‐eastern Brazil. We measured the relative impor‐ tance of deterministic and stochastic processes by redundancy analysis (RDA) and variation partitioning in comparison with null expectations using ad hoc generated neutral communities. Furthermore, we accessed species associations from co‐occur‐ rence data, at different scales using a Bayesian approach of Hierarchical Modelling of Species Communities. Results: Overall, the extent to which stochastic and deterministic processes affected community assembly depended on the forest type and the spatial scale. Specifically, we found that abiotic and biotic predictors of AM fungal community assemblages are related to environmental homogeneity in tropical rain forests. Main conclusions: The results of the study show that dynamics in community assem‐ bly was clearly different between the two forest types, and that the difference most likely is due to differences in responses to environmental variables. KEYWORDS Atlantic forest, beta‐diversity, biotic associations, fungal communities, Glomeromycotina, neutrality, next generation sequencing, SSU rRNA gene