Geopedological influence on the wood anatomy of Gymnanthes klotzschiana (Euphorbiaceae) in a subtropical riparian forest, in Southern Brazil

Abstract

The wood anatomy of Gymnanthes klotzschiana was studied, to assess whether there are variations in the secondary xylem under different geopedological conditions. The species is dominant in subtropical alluvial forests and can be established in different ecological conditions, especially regarding soil water regime. Wood samples were collected in the plain of the Iguaçu River, in Paraná, Brazil, encompassing three geopedological conditions: gleysol, fluvisol and psamment, characterized by varying degrees of water saturation, ranging from very poorly drained to heavily drained. Considerable intraspecific variations were found in the xylem in response to geopedological conditions. Most of the variation occurs in attributes related to the biomechanical and hydraulic functions (e.g. fibers and vessels), with cells smaller in gleysol, larger in fluvisol and intermediate in psamment. For some variables, the xylem has similar responses in conditions of water deficit and permanent water saturation, indicating a probable influence of physiological drought. The phenotypic plasticity of the species explains its high adaptability to the selective and variable conditions of riparian environments. The study contributes to understanding the species’ ecological responses, highlighting its relevance as a keystone species in the dynamic and fragile ecosystems of the floodplains, fundamental for the maintenance of many ecosystem services.