Semiarid woody plant functional groups contribute differently to canopy conductance

Abstract

The continuous exploitation of tropical dry forests has caused changes in the hydrological cycle. Although the vegetation-atmosphere relationship is climatically important, studies evaluating the contribution of plant functional groups to canopy conductance remain scarce. This study aimed to evaluate the relationship between the morphophysiological characteristics of different plant functional groups and canopy conductance in a semi-arid region. We assessed canopy conductance, stomatal conductance, leaf temperature, water potential, and xylem vessel biometry in high wood density species (HWD) and low wood density species (LWD). Using repeated measures analysis of variance and Pearson's correlation analysis, we found a strong positive correlation between stomatal conductance and canopy conductance (ρ = 0.917). The HWD group exhibited a higher number of xylem vessels (90%) and thicker vessel walls (37%). These traits enabled greater stomatal conductance activity (66%) throughout the season (dry/rainy). Conversely, the LWD group had wider vessel lumens (47%), which facilitated higher stomatal conductance during the rainy season (33.3%) and increased water potential (70%). These findings demonstrate that functional groups contribute differently to canopy conductance and highlight the importance of functional diversity for maintaining ecohydrological systems in dry forests.