Relationship between ecological breadth of vascular epiphytes and their ecophysiological responses to light availability and moisture in the Sclerophyllous Mediterranean Coastal Forest of Chile

Abstract

Epiphytic microhabitat is exposed to microclimatic variations due to the local climate, forest structure and its dynamics. Consequently, the establishment, development and ecological breadth of epiphytes species depend on the ability to modify their physiology, morphology and phenology facing environmental restrictions. In this study the differences in ecological breadth of vascular epiphytes in relation with light availability and soil moisture are decribed in a relict stand of Mediterranean Coastal Sclerophyllous Forest located in Península de Hualpén, Biobío Region (36º47’S y 73º10’S). We quantifi ed the field distribution of each epiphyte species along these two gradients. We measured in situ variation in leaf relative water content (RWC), leaf chlorophyll content (Chl), and specifi c leaf mass (LMA). Seven vascular epiphytes species (two Angiosperms and fi ve Pteridophytes) were found and some of them showed clear differences in their ecological breadth in both environmental gradients. Sarmienta scandens (Gesneriaceae), Asplenium trilobum (Aspleniaceae) and Pleopeltis macrocarpa (Polypodiaceae) were the most abundant species and they also showed higher ecological breadth both in the light and soil moisture gradients. For these species the change in Chl could be an important mechanism for acclimation under variation of the moisture conditions. Finally, although no relation between the ecological breadth in the light gradient and the leaf traits was found, our results suggest that the species composition is related to the light availability in the host trees.