Evidence of foliar aluminium accumulation in local, regional and global datasets of wild plants

High foliar concentrations of aluminium (Al) have been reported in numerous plant species, but progress on the understanding of the functional significance of this trait is constrained by the absence of a quantitative analysis of its distribution among plant lineages and across biomes. We constructed a global dataset of foliar Al and nutrient concentrations for 1044 plant species from literature sources and new data collections in Brunei Darussalam. Our results provide statistical support for the existence of Al accumulators and non-Al accumulators in global, regional and local floras based on foliar Al concentrations. A value of 1 mg Al g-1 leaf dry mass is a suitable threshold to distinguish between these two groups in a sample of species that lacks any geographical reference. However, a higher threshold foliar Al concentration is required to distinguish between Al accumulators in tropical (2.33.9 mg Al g-1 leaf dry mass) than in temperate (1.1 mg Al g-1 leaf dry mass) floras. There was a phylogenetic signal in the foliar concentrations of Al, but phylogeny did not explain the difference in the mean foliar Al concentration between tropical and temperate floras in a phylogenetically controlled analysis. Phylogeny and soil chemistry are potential factors driving Al accumulation in certain groups of plants.