Plant Functional Traits of Carapa guianensis, a Widespread Tropical Tree, Adapted to Local Climate Conditions at Two Elevations in Costa Rica
Abstract
Tropical rainforests are among the most biodiverse ecosystems in the world. However, plant species occurrences are highly dependent on localized topography, elevation, and climate. Convergent evolution has been studied extensively to identify key plant traits that vary along those gradients, which contributes to a greater understanding of how species adapt to climate variation. This project investigated leaf physiological and anatomical trait variation within a select tropical tree species, Carapa guianensis Aubl, which thrives in a wide range of elevations and climates within Central and South America. At two sites in Costa Rica, four leaves were sampled on each of three sample trees of C. guianensis growing at approximately 400-600 m (Texas A&M University Soltis Center) and approximately 830 m elevation (Pocosol Biological Preserve), in which we measured leaf photosynthesis and stomatal densities. We further assessed photosynthetic responses across a range of light intensities to determine the maximum potential photosynthesis of trees occurring at contrasting elevations. We found that stomatal density was higher at decreasing elevations, possibly as a means to compensate for less cloud cover. Furthermore, C. guianensis trees located in lower elevations had higher net photosynthesis rates (PNmax) than trees sampled at higher elevations, after accounting for differences in leaf temperature. These findings suggest that lower elevations with higher light intensity can significantly drive critical plant processes. Hence, further experiments are needed, not only to explore plant functional traits in species adapted to occur across wide ranges of elevations, but climatic changes that drive them, especially in our current global scenario in which tropical forests are expected to have higher temperatures and longer dry periods.
Citation
Flores, Manuel Romeo (2020). Plant Functional Traits of Carapa guianensis, a Widespread Tropical Tree, Adapted to Local Climate Conditions at Two Elevations in Costa Rica. Undergraduate Research Scholars Program. Available electronically from https : / /hdl .handle .net /1969 .1 /194464.