Ionomics suggests niche differences between sympatric heathers (Ericaceae)

Abstract

The co-existence of large number of competing plant species with the same basic needs is a major question in ecology, particularly when this involves closely related species. We investigated the ecology of six heather species (Calluna vulgaris & Erica spp., Ericaceae) able to cohabit in the same heathlands. We characterised the ionome, i.e. the mineral composition of the plants using a sampling strategy specifically designed to control for soil effects. Nine plant communities in Limousin, France, were investigated, representing eight combinations of different species, on serpentine and non-serpentine substrates. Ionome was influenced by both taxonomic and environmental factors with significant interactions between them. We found that species growing in sympatry had distinct ionomic profiles, i.e. they differ in their leaf mineral content, suggesting different nutritional strategies. Different mycorrhizal associations may be hypothesised to explain these different chemical signatures. Differential use of the soil nutrients could explain the co-existence of closely related species. It may also explain the diversity of certain shrubby ecosystems or large shrubby genera such as Erica. Ionomics is therefore a promising tool for ecological studies in non-model organisms.