Evolutionary history shapes plant elementome and biogeochemical niches in a forest-steppe ecotone

Background and aims

The biogeochemical niche framework, which estimates plant species niches based on their elemental composition (elementome), offers valuable insights into plant nutritional strategies, community assembly, and elemental cycling within ecosystems. Although the biogeochemical niche hypothesis has been validated in various terrestrial ecosystems, its application in transitional zones between contrasting biomes, such as in Eurasian forest-steppe ecotones, remains underexplored.

Methods

This study investigates the biogeochemical niche framework in seven sites along a gradient from closed-canopy forests to forest-steppe ecotones and meadow steppes in northeastern China, which constituents a critical component of the Eurasian biome. We analyzed the concentrations of ten essential elements—both macro- and micro-elements—in leaves of the dominant plant species, and assessed the elemental compositions and physicochemical properties of the soil at each site.

Results

We found substantial differences in leaf elementomes among species across the three habitats, primarily attributed to phylogenetic legacy and species taxonomy. Woody plants in the ecotone exhibited higher leaf elemental homeostasis compared to herbaceous plants; the latter displayed notable elemental plasticity.

Conclusions

Results from this study highlight the applicability of leaf elementome as a universal metric for comparing species niches across different life forms. Moreover, our findings offer empirical support for the biogeochemical niche conservatism assumption, suggesting that species-specific elemental utilization is a critical niche differentiation process in driving species coexistence within Eurasian forest-steppe ecotones.