How Do Variation and Covariance of Leaf Functional Traits Influence Schinus terebinthifolia Raddi (Anacardiaceae) Acclimation to Light and Water Availability in Tropical Dry Ecosystems?

Light availability in tropical forests varies spatially and temporally, strongly influencing plant acclimation. Understanding variation and covariation among functional traits associated with photoacclimation is essential for predicting plant responses to environmental change. Here, we investigated acclimatory responses of Schinus terebinthifolia Raddi (Anacardiaceae), a widespread Neotropical species adapted to heterogeneous light environments. We evaluated variation and covariation in morphological, anatomical, physiological, and nutritional traits under contrasting light conditions. Under high light, plants invested more resources in palisade parenchyma and subepidermal layers while maintaining water-use efficiency, indicated by higher δ13C values. Irregular adaxial cuticles and unstacked thylakoid membranes were also observed under high irradiance. The strongest covariation occurred among anatomical traits, especially spongy parenchyma and adaxial and abaxial cuticles. Overall, the relationship between trait variation and covariation was slightly negative but not significant, although patterns differed among functional groups. These findings demonstrate that photoacclimation in S. terebinthifolia involves coordinated functional strategies that optimize light modulation, water conservation, and photosystem II performance under variable tropical light environments.