Scale dependence in abundance-environment relationships
Since FIA is a systematic survey program, we considered the absence of a species’ record in a plot as a true absence. Thus, we analyzed whether there is scale-dependence in tree abundance-environment relationships, that is, whether models for species with wide geographical or environmental range are better than models for species with narrower environmental or geographical range. To do that, we calculated Spearman correlations between model´s ∆AIC and species’ area of occupancy, extent of occurrence, and environmental breadth. The area of occupancy was estimated as the number of plots occupied by the species divided by the total number of plots in the database (89,369 plots). The extent of occurrence was calculated as the minimum convex polygon of all occurrences (MCP - IUCN, 2019) and given as the proportion of the extent occupied by each species divided by the total available geographical space. Finally, we calculated the environmental breadth as the proportion of the environmental space occupied by the species in relation to the total available environmental space by applying the Schoener’s D index (Schoener, 1974; Broennimann et al. , 2012; Ronquillo et al. , 2020).