Unfolding long-term Late Pleistocene-Holocene disturbances of forest communities in the southwestern Amazonian lowlands

Autor(es)

Rossetti, Dilce F. ^[1] ; Gribel, Rogerio ^[2] ; Toledo, Peter M. ^[1] ; Tatumi, Sonia H. ^[3] ; Yee, Marcio ^[3] ; Tudela, Diego R. G. ^[4] ; Munita, Casimiro S. ^[5] ; Coelho, Luiz de Souza ^[2]

Afiliação do(s) autor(es)

^[1] Brazilian Inst Space Res INPE, Rua Astronautas 1758, BR-12245970 Sao Jose Dos Campos, SP - Brazil

^[2] Brazilian Natl Inst Amazonian Res INPA, Coordinat Biodivers, Ave Andre Araujo 2936, BR-69067375 Manaus, AM - Brazil

^[3] Univ Fed Sao Paulo, BR-11070100 Santos, SP - Brazil

^[4] Univ Sao Paulo, BR-05508900 Sao Paulo, SP - Brazil

^[5] Inst Nucl Res, BR-05508900 Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: ECOSPHERE; v. 9, n. 10 OCT 2018.
• Citações Web of Science: 1

Resumo

Linking the distribution of plant species to geology has generally been biased by the over-simplification of landscape evolution and the lack of understanding of complex geological processes. The Amazonian lowlands have forests in different successional stages, and a growing perception is that such heterogeneity results from long-term environmental changes. This hypothesis is investigated by designing an analytical model based on past and present-day vegetation and successions of the plant communities, combined with an advanced understanding of geological history. An area of southwestern Amazonia was selected for floristic inventories, and we interpreted the paleovegetation based on C/N and delta C-13 analyses of sedimentary organic matter. These data were examined in the context of the geological evolution on the basis of new sedimentological and chronological data. The topographically high Late Pleistocene deposits had continuous and highly diversified late-successional terra firme forests as well as local fluvial paleolandforms of younger ages with less diversified campinarana forests. Late Pleistocene-Holocene terrains in intermediate elevations had terra firme forests, but shorter trees with lower basal areas and ecotonal forests appeared near the confines of the forest-savanna, while Holocene deposits recorded only seasonally flooded varzea forests. Several deposits of Late Pleistocene and Late Pleistocene-Holocene age recorded an expansion of C-4 terrestrial plants before the establishment of the forest from similar to 20,000 cal yr BP to 7578 cal yr BP, which is not related to past arid episodes. We recorded forests with onsets at 6130-3533 cal yr BP, 3402-2800 cal yr BP, and 1624-964 cal yr BP to terra firme, varzea, and ecotonal forests, respectively. However, not all forests have reached maturity stages due to their location on terrains with a diverse history of terrace downcutting and deposition, which had a direct impact on local hydrology with the interaction of topographic gradients. The hydrology of the study area was also controlled by the distance from the main river valley. Capturing long-term disturbances over this region of still pristine forests may help elucidate the potential mechanisms that also determine trends in tree growth and forest diversity in other Neotropical regions. (AU)

• Processo FAPESP: 09/02069-2 - Implantação e desenvolvimento da metodologia de datação de grão-único, por luminescência opticamente estimulada
• Beneficiário: Sonia Hatsue Tatumi
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 13/50475-5 - Mapping Amazonian biodiversity at multiple scales by integrating geology and ecology
• Beneficiário: Dilce de Fátima Rossetti
• Modalidade de apoio: Auxílio à Pesquisa - Regular