Environmental influences on stomatal traits of mangrove Ceriops decandra (Griffith) Ding Hou in the Sundarbans, Bangladesh

Quantifying how stomatal traits respond to multiple interacting environmental variables is crucial for understanding plant adaptations under changing environment. Based on trait and environmental data collected from the three salinity zones (less saline, medium saline and high saline zones), and using ANOVA and Generalized Additive Models (GAMs), we aimed to understand the effects of environmental variables (i.e., salinity, siltation, pH, light and soil nutrients) on stomatal morphology in an important shrubby mangrove Ceriops decandra in the Bangladesh Sundarbans. Specifically, we asked: (1) how do stomatal density (SD), stomatal pore length (SPL), stomatal pore width (SPW), guard cell length (GCL) and guard cell width (GCW) vary across the salinity zones? and (2) how do environmental variables influence stomatal traits in C. decandra ? We found that the species forms stomata on the abaxial surface (hypostomaty) of leaves. Albeit SD, SPL and GCL did not vary significantly, SPW and GCW varied significantly across the salinity zones with wider SPW and narrower GCW in less saline areas. GAM models for SPW (49%) and GCW (44%) showed higher explanatory powers than other stomatal traits. Among the environmental traits salinity had the strongest effect on SPW (negative) and GCW (positive) and P and K had strong effects on SPW and GCW, respectively, although leaf area index (LAI) had less influence on the stomal traits. The trade-off between SPW and GCW in regulating stomatal pore areas in response to fluctuating habitat conditions suggests that C. decandra can efficiently maintain its gas exchange capacity under stress, thus offering us an example of how plants may acclimatize under changing environments.