Phytophysiognomy in the east of the Marajó island (mouth of the Amazon River) from the perspective of geological history in the Late Quaternary

• Published in: Catena (Giessen) 2023-01, Vol.220, p.106711, Article 106711
• Main Authors: do Amaral, Dário Dantas, de Fátima Rossetti, Dilce, Gurgel, Ely Simone Cajueiro, Pereira, Jorge Luis Gavina
• Format: Article
• Language: English
• Subjects: Amazonian lowlands; Geological history; Late Quaternary; Pioneer vegetation; Vegetation patterns
• ISSN: 0341-8162; 1872-6887
• DOI: 10.1016/j.catena.2022.106711

•Marajó island had a highly dynamic geological history in the late Quaternary.•The Holocene detachment of this island diversified the depositional environments.•The island also has marked variations in vegetation patterns on a regional scale.•Fauls led to lithological and topographic contrasts that controlled plant growth.•The recent geological history is dissonant with the time needed for plant speciation. The origin of many ecological environments that have controlled plant development in Amazonia has been linked to Andean growth in the Neogene and/or glacial/interglacial fluctuations in the Pleistocene. In addition, studies have recognized that natural or tectonically induced changes in lithology and/or depositional history may have also played a key role in determining the Amazonian vegetation patterns. However, this hypothesis remains to be further investigated, as the available data are generally scattered in relation to the high size and geological complexity of this region. Investigations in areas with known geological history should be prioritized to address this issue. The Marajó island, at the mouth of the Amazon River, is one area where the geological evolution of the Late Quaternary has been provided based on a large volume of systematic data. This island also has marked changes in vegetation patterns ranging from grasslands to typical rainforest, despite the flat relief and uniform equatorial climate. These characteristics collectively make the Marajó island a key site for studying the relationship between geological processes and vegetation patterns in the Amazonia. This study aimed to address this topic by combining available geological data with the description of plant formations and environmental physiognomy from the east of the Marajó island on a regional scale. The results revealed marked correlation patterns between plant types and geological parameters. These parameters were defined by faulting during the Late Quaternary, when the island was detached from the mainland. This geological event contributed to diversify the depositional environments and create lithological and topographic contrasts that controlled the distribution of the various plant types along the island. The formation of the Marajó island in the Late Quaternary may also explains the lack of endemism in the plant community, prevailing the assumption that the recent geological history is dissonant with the time required for plant speciation.