Vegetation structure and relationship with geomorphological processes and fluvial regime in the Três Ilhas Archipelago, Upper Paraná River

Abstract

The Paraná River is Brazil's second biggest river, and in its upper reach presents a multichannel pattern formed by 264 islands of different dimensions and ages of formation. Depending on their genesis and evolutionary history, the islands present sub-environments of varied morphology (levee, paleobar, and paleoblind-channel) with variations in topography and different degrees of channel connectivity. This study aims to attest to whether the tree vegetation distribution in the Três Ilhas Archipelago sub-environments is related to the topography (morphology) and the channel flooding regime. The study methodology includes the hydrological characterization of the stretch and the topographic and phytosociological arboreal vegetation survey of the sub-environments of each island of Três Ilhas Archipelago. Thus, it was possible to obtain the phytosociological parameters, succession group, and dispersion syndrome related to the arboreal species of the different sub-environments. Although it is common consensus in the literature that these variables are responsible for plant distribution in the Upper Paraná River region, including all plant life forms, the statistical results showed that only the tree species did not present this specific pattern. The vegetation structure of the sub-environments is related to geomorphology and hydrology, in which the higher elevation values of the sub-environment correspond to the higher values of vegetation structure (area and basal volume).