Spatial relationship between congeners
Due to the overall association of the three Myrcia species to patches subject to flooding, the spatial association between congeners should be expected. Nevertheless, only medium trees of M. multiflora and M. racemosa were spatially associated due to the same habitat-association. All other congener spatial relationships were independent, which has been frequently shown for tropical tree species (Wiegand et al. , 2012; Wang et al. , 2016). One explanation is that positive and negative interactions between species cancel each other’s effects out (note that there are many more species competing in our plot with the three species studied), resulting in spatial patterns that appear on overall independent (Punchi-Manage et al. , 2015). Also, according to the stochastic dilution hypothesis, independence increases with species richness in rich forests such as in the tropics, due to large variability of neighbour’s trees that inhibit the detection of the spatial arrangement of plants directed by interactions between species (Wang et al. , 2016). The apparent spatial independence between congeners likely explains the independence between tree size and distance between congeners when we considered environmental heterogeneity in our analysis (i.e. local random marking null model). The evaluation of plant performance in greenhouse experiments and functional traits related to resource acquisition could help to elucidate whether the three Myrcia species use resources differently, as expected by niche differentiation of sympatric species with similar environmental requirements due to strong competition in the past (Connell, 1980).