Conclusions
Leaf adaptation to climate may not be limited to a single or even a few traits but to a suite of traits representing a meaningful ‘syndrome’ that may be helpful for understanding vegetation response to climate change without detailed analysis of each species (Wright et al. , 2001; Reich et al. , 2003). Our results suggest that C4 grasses adapted to low MAP exhibit greater SDada, SR, Smes and gm, which allow for greater photosynthetic C-gain. Additionally, C4 grasses adapted to low MAP also exhibit greater average leaf thickness, average VED and BSCW but lower BSias which may lead to lower Kleaf and transpirational water-loss. Taken together, this entire suite of traits (collectively represented by PC1) was positively correlated with Anet and Anet/E (Fig. 7) indicating that C4 grasses adapted to relatively drier habitats exhibited greater photosynthetic C-gain and leaf-level WUE. This ‘syndrome’ of C4 grasses appears important for adaptation to drier habitats and could be useful to identify or screen for agriculturally important C4 grasses with greater productivities and leaf-level WUE (Sack et al. , 2016). Furthermore, a negative relationship of Kleaf with gm, predicted in current study for C4grasses belonging to habitats with diverse MAP, warrants further investigation as it could have important implications for modelling the carbon and water fluxes of grasslands (De Kauwe et al. , 2015; Knauer et al. , 2019a; Knauer et al. , 2019b).