Aim: Plant community assembly in tropical rainforest 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 rainforest (semideciduous rainforest and dense ombrophilous forests). Location: Atlantic rainforest in northeastern Brazil, South America. Taxon: Arbuscular mycorrhizal fungi (Glomeromycota). Methods: We collected root samples from eight protected areas of Atlantic forest along a 700 km transect in northeastern Brazil. We measured the relative importance 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-occurrence data, at different scales using a Bayesian approach of Hierarchical Modelling of Species Communities (HMSC). 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 rainforests. Main conclusions: The results of the study show that dynamics in community assembly was clearly different between the two forest types, and that the difference most likely is due to differences in responses to environmental variables.