Responses of photosynthetic and stoichiometric traits to aridity in species and functional types of two Sonoran Desert plant communities

Abstract

Background: Plants in drylands have developed several water use efficiency (WUE) adaptations, although nutrient limitations and excess irradiances affect also their performance. Previous findings of high photosynthetic rates and nitrogen concentration in leaves, may contradict the known low productivity in their communities. Questions: How different are leaf ecophysiological and stoichiometric traits in dryland species? Did species favor higher water or nutrient use efficiencies in contrasting dryland communities? Studied species / data description /Mathematical model: Calliandra eriophylla, Cercidium microphyllum, Encelia farinosa, Eysenhardtia orthocarpa, Fouquieria diguetii, Fouquieria macdougalii, Ipomoea arborescens, Jatropha cardiophylla, Jatropha cordata, Larrea tridentata, Mimosa laxiflora, Olneya tesota and Prosopis velutina. Study site and dates: Sonoran Desert, Central Sonora Region, Mexico. August - September 2019. Methods: Ecophysiological and stoichiometric leaf traits were measured and analyzed for dominant species and functional types from two Sonoran Desert plant communities. Results: We found greater variability in photosynthetic and fluorescence traits than in elemental composition (Nmass, Pmass) and stoichiometry ratios. Species in the arid site tend to have higher photosynthetic rates and photochemical integration but low WUE. In the semiarid community, leaf traits were associated to higher elemental composition (Nmass, Pmass) but low stoichiometric ratios and nitrogen use efficiency (NUE). Conclusions: Leaf Traits in Sonoran Desert species and functional types correlated with photoprotective mechanisms rather than instantaneous resources use efficiencies, to ensure long term C gain.