Empirical support for the biogeochemical niche hypothesis in forest trees


The possibility of using the elemental composition of species as a tool to identify species/genotype niches has been tested at the global scale by investigating the relationship between the foliar elemental compositions (the “elementome”) of trees with phylogeny, climate, N deposition and soil traits. The foliar N, P, K, Ca, Mg and S concentrations in 23,962 trees of 227 species was analyzed. Shared ancestry explained 60–94% of the total variance in foliar nutrient concentrations and ratios whereas current climate, atmospheric N deposition and soil type together explained 1–7%, consistent with the biogeochemical niche hypothesis which predicts that each species will have a specific need for and use of each bio-element. The remaining variance was explained by the avoidance of nutritional competition with other species and natural variability within species. The biogeochemical niche hypothesis is thus able to quantify species-specific tree niches and their shifts in response to environmental changes.