Structural adjustment of Schwartzia brasiliensis (Marcgraviaceae) in two restinga formations

Abstract

This study investigated the foliar plasticity in Schwartzia brasiliensis in restinga formations (shrub and shrub-tree restinga) in southern Brazil. In each area, 10 individuals were selected and leaves in sunlight were collected for an analysis of functional leaf traits, including: fresh and dry leaf mass, leaf area, specific leaf area, succulence, stem diameter, plant height and tissue thickness. Environmental variables were measured considering soil mineral nutrition, water availability and photosynthetically active radiation. Phenotypic plasticity index was calculated for studied attribute. We compared means with a Student’s t-test and the weight of environmental variables with a PCA. Results showed that the main leaf traits that differentiated the populations were leaf dry mass, specific leaf area, lamina thickness and plant height, while the main predictor environmental variables were gravimetric humidity, solar radiation, soil CEC, phosphorus content and salinity. In the shrub restinga, there is greater investment in mechanical support as a water saving strategy due to greater exposure to solar radiation. In the shrub-tree restinga, there is greater investment in photosynthetic production, since the shade provided by the treetops of other species attenuates the radiation effect. Despite the low plastic potential, the populations present structural adjustments that respond to the environmental heterogeneity.

Keywords:
ecological anatomy; environmental heterogeneity; functional leaf traits