• global change;
  • Larrea tridentata;
  • nitrogen;
  • photosynthesis;
  • water relations


  • • 
    Leaf-level CO2 assimilation (Aarea) can largely be predicted from stomatal conductance (gs), leaf morphology (SLA) and nitrogen (N) content (Narea) in species across biomes and functional groups.
  • • 
    The effects of simulated global change scenarios, increased summer monsoon rain (+H2O), N deposition (+N) and the combination (+H2O +N), were hypothesized to affect leaf trait-photosynthesis relationships differently in the short- and long-term for the desert shrub Larrea tridentata.
  • • 
    During the spring, +H2O and +H2O +N plants had lower Aarea and gs, but similar shoot water potential (Ψshoot) compared with control and +N plants; differences in Aarea were attributed to lower leaf Narea and gs. During the summer, +H2O and +H2O +N plants displayed higher Aarea than control and +N plants, which was attributed to higher Ψshoot, gs and SLA. Throughout the year, Aarea was strongly correlated with gs but weakly correlated with leaf Narea and SLA.
  • • 
    We concluded that increased summer monsoon had a stronger effect on the performance of Larrea than increased N deposition. In the short term, the +H2O and +H2O +N treatments were associated with increasing Aarea in summer, but also with low leaf Narea and lower Aarea in the long term the following spring.