Format: ORAL

Carmen Regina Marcati1 Paula Cristina Benetton Vergilio2 Julieta Alexandra Rosell3

1 - Laboratório de Anatomia de Madeira e Casca, Departamento de Ciência Florestal, Solos e Ambiente, Faculdade de Ciências Agronômicas, Universidade Estadual Paulista (UNESP), Botucatu, Brasil. 2 - Colegiado de Ciencias Biológicas, Universidade Estadual do Paraná (UNESPAR), Paranaguá, Paraná, Brasil. 3 - Laboratorio Nacional de Ciencias de la Sostenibilidad, Instituto de Ecología, Universidad Nacional Autônoma de México, Ciudad de México, Mexico

Covering roots and stems of woody plants, bark is a structurally complex system with functions ranging from conducting photosynthates, and other compounds, to protect the plant. Bark is composed mainly by the secondary phloem, arising from the cambium, and the periderm, arising from the phellogen. Although variation in bark structure across species has been widely examined, little is known about the patterns of bark variation across woody organs. Structural and functional variation would be expected between bark of roots and stems in fire-prone plant communities as a result of the contrasting selective regimes experienced by these above- and below-ground organs. We tested this hypothesis by comparing bark anatomical and functional traits between coarse roots and main stems of species from the Brazilian savanna (Cerrado), the most frequently burnt vegetation globally. We sampled the barks from coarse roots and main stems of 15 species of trees and shrubs with high phylogenetic diversity and followed standard anatomical techniques. We observed that the secondary phloem is similar between roots and stems, except that rays in roots were taller than stems suggesting adjustments in radial conduction, and storage in roots, likely associated with resprouting after fire and drought tolerance. The periderm showed more protective traits in stems, mainly higher phellem development, indicating protection against fire. This was observed since the formation of the first periderm, and also when rhytidomes were present. These data indicate that, although the cambium is barely influenced by its position in different organs, the phellogen is influenced by the environmental differences to which the organ is exposed.