Geobotany in a fault in the world’s largest continuous wetland in central South America

Abstract

The Pantanal is located in the center of South America in a tectonically active sedimentary basin of Quaternary age. Even though the relief is flat and the diversity of the sediments is low, its vegetation cover has high variability resulting from seasonal fluctuations in water levels and the presence of four surrounding biomes. Changes in elevation of less than 1 m influence the length and intensity of floods, powerfully affecting the vegetation. Faults with small vertical displacement can generate abrupt vegetation changes and, consequently, expressive vegetation lineaments. This study characterizes a lineament in the northern Pantanal, considering Land Surface Phenology, estimates of precipitation, and floristic survey. The phenological metrics, obtained from a 15-year time series from the Moderate Resolution Imaging Spectroradiometer processed by TIMESAT software, discriminate evergreen forests in the NW of this lineament from savanna-like physiognomies in the SE region. Plant taxonomic identification shows two distinct regional strata with a clear separation between species adapted to prolonged floods in the NW and typical species of the Cerrado biome, mostly xeromorphic, in the SE. Data from the Tropical Rainfall Measuring Mission complemented the analysis, showing different dependence on local rains on different sides of the lineament. The entire dataset defines this geological structure as a driver of the Pantanal’s plant communities, being a boundary for the extensive establishment of propagules of the Amazon biome. This research, in addition to advancing knowledge of this singular region, which is essential for management studies, can be a stimulus to biological and forest investigations.