Paleoenvironmental dynamics in central‐eastern Brazil during the last 23 000 years: tropical peatland record in the Cerrado biome

Abstract

The Cerrado biome is the second largest in Brazil, but the evolution of the Cerrado during the late Quaternary is not yet fully known. This study identifies paleoenvironmental changes during the last 23 000 years, based on a tropical mountain peatland record, in the Serra do Espinhaço Meridional in central-eastern Brazil. A multi-proxy approach was used that involved palynological analysis, stable isotopes (δ 13 C, δ 15 N), geochemistry, radiocarbon dating and multivariate statistics derived from a peatland core from Rio Preto (Minas Gerais state). The study reveals a very humid and cold climate during the late Pleistocene, with an increase in temperature and decrease in humidity at the Pleistocene-Holocene transition. During this period there was strong instability in the landscape (episodes of erosion). At the beginning of the Holocene there was a reduction in humidity with greater landscape stability. The current sub-humid climatic conditions seem to have been established in the mid-/late Holocene, with periods of landscape instability. Our findings agree with other Cerrado records that contradict previously established hypotheses, such as the Amazonian Refuge and the Pleistocene Arc.

Comparative phylogeography reveals the demographic patterns of neotropical ancient mountain species

“…This high credible interval associated with this kind of analysis is a common nuisance as already noticed by Gehara et al (2017) due to the stochasticity of the coalescent processes in the genetic markers used here. Nonetheless, the expansion pattern of the plant community during ancient cold periods are corroborated by paleopalinological studies over the region, which shifted to herbaceous vegetation towards lowlands, supporting the role of ancient climatic oscillations on the biological community structure (Barberi et al, 2000; Costa et al, 2022; Horák‐Terra et al, 2015, 2020; Silva et al, 2020). Therefore, whenever the concerted expansion happened, the climatic oscillations were strong drivers that influenced the demographic dynamics of the BQM community.…”

“…The BQM mountain ecosystem has attracted the attention of generations of scientists interested in unveiling the evolutionary dynamics that generated such an amazing biota, where the geological stability and ancient climatic oscillations on the BQM are considered the preponderant drivers of its high endemism (Antonelli et al, 2010; Barres et al, 2019; Ribeiro et al, 2014, but see Rapini et al, 2021). Paleopalynological studies support the view of a vegetation turnover over the Last Glacial Maximum (LGM, c. 21 thousand years ago) and the Last Interglacial (LIG, c. 120 thousand years ago) (Barberi et al, 2000; Costa et al, 2022; Horák‐Terra et al, 2015, 2020; Silva et al, 2020), suggesting pulses of connection and disconnection due to climatic changes over time between populations now isolated in adjacent mountains due to their high specificity to mountain environments. In this way, the flickering connectivity between adjacent BQM can be considered as a possible explanation to clarify how a rich endemic biota could emerge in these ancient neotropical mountains.…”