Leaf trait variation in three species through canopy strata in a semi-evergreen Neotropical forest

Abstract

Morphological and structural changes among and within leaves of Aphananthe monoica (Hemsley) Leroy, Pleuranthodendron lindenii (Turczaninov) Sleumer, and Psychotria costivenia Grisebach were documented through canopy strata (<10, 10–20, and >20 m high) and related to some environmental variables in a semi-evergreen Neotropical forest. The principal components analysis revealed that two components explained 93% of total variation. The first component (76.4%) denoted leaf structure, whereas the second (16.6%) denoted leaf shape. Anatomical differences in transverse leaf sections among different canopy strata were observed in Aphananthe monoica and Pleuranthodendron lindenii. Variance analyses showed significant differences among strata for leaf characters and light, relative humidity, vapour pressure deficit, and temperature. Canonical correlation analysis revealed that the first pair of canonical variates of leaf characters and environmental variables were closely related. The first environmental variate represented the changes in microclimate along forest canopy strata. Leaf structure observed in Aphananthe monoica and Pleuranthodendron lindenii suggested that they are intermediate shade-tolerant species, and Psychotria costivenia is a shade-tolerant understorey species. Aphananthe monoica and Pleuranthodendron lindenii, which during their life span occupy different positions in the vertical strata, showed the highest leaf variation.Key words: tropical trees, Aphananthe monoica, Pleuranthodendron lindenii, Psychotria costivenia, leaf variation, Veracruz.