The relationships between photosynthesis and stomatal traits on the Loess Plateau

Stomata control the water loss for transpiration and the CO2 uptake for photosynthesis. However, the relationships between photosynthesis and stomatal traits across a wide range of species are largely been unknown. Here, we tested the relationships among maximum photosynthetic rate (Amax), stomatal density (SD), stomatal length (SL) and maximum stomatal conductance to water vapour (gmax) across 45 woody plants on the Loess Plateau. We found the correlations of stomatal traits with Amax and gmax were different. Specifically, gmax was positively correlated with SD. Amax was negatively correlated with SD and positively correlated with SL, which were inconsistent with previous findings focusing on a few of species. Our results indicated that plants with large and few stomata could possess low gmax and maintain an appropriate photosynthetic rate, suggesting that it will benefit plants under increased CO2 and decreased water availability environments in the future. Indeed, further work is needed to investigate the effects of stomata, mesophyll and biochemical process on photosynthesis under different environmental conditions.