Shifts in plant resource use strategies across climate and soil gradients in dryland steppe communities

Background and aims Despite being Earth’s largest biome and a key contributor to global energy budgets, arid regions (or drylands) are critically understudied relative to mesic ecosystems. Here we clarify how dryland species vary in their functional traits across environmental gradients. Methods We measured nine traits reflecting resource use for 68 species inhabiting dryland steppe communities across northwestern China. We tested predictions from various theoretical frameworks including the leaf economics spectrum, leaf energy balance theory and least-cost optimality theory. Results Species on drier or sunnier sites had smaller leaves with higher LMA, higher leaf nitrogen concentration per area (N area ), and a greater drawdown of CO 2 during photosynthesis (i.e., lower C i :C a ) suggesting higher photosynthetic water use efficiency. Leaf nitrogen per mass and plant height (typically