Higher phosphorus and water use efficiencies and leaf stoichiometry contribute to legume success in drylands

Abstract Legumes are essential plants in dryland ecosystems worldwide because they increase nitrogen availability, so their understanding is vital for improving knowledge and modelling in the face of climate change. This work studies the differences in resource use efficiency and their relationship with photosynthetic, photochemical, bioelemental, and stoichiometric traits of coexistent legumes and non‐legumes in a Sonoran Desert ecosystem. We found that legumes had higher photosynthetic rates, intrinsic and seasonal water use efficiency (WUE), phosphorus use efficiency (PPUE), and higher light utilisation mediated by chlorophyll content and active reaction centers, which may increase their photoprotection. Legumes can increase their WUE and PPUE with no changes in nitrogen use efficiency (PNUE). Consequently, observed trait relationships between studied traits in these legumes have significant differences with the non‐legume species in the study. Stoichiometry is helpful, in some cases, as an indicator of nutrient use efficiency and enables functional group differentiation. Our results strongly relate legumes' higher resource use efficiency with their success in dryland ecosystems. Read the free Plain Language Summary for this article on the Journal blog.