Skip to main content

A mid-Holocene environmental change in Amazonian savannas

Buy Article:

$51.00 plus tax (Refund Policy)

Abstract Aim 

The main goal of this study was to investigate how climate and human activities may have influenced ecotonal areas of disjoint savannas within Brazilian Amazonia. Location 

Eastern Brazilian Amazonia, Amapá State. Methods 

The fossil pollen and charcoal records of two lakes in Amapá (Marcio and Tapera) were used to provide a Holocene palaeoecological history of eastern Amazonian savannas. Detrended correspondence analysis was used to enhance the patterns of sample distribution along the sediment core. Results 

Even though sedimentary hiatuses were recognized in the sediment cores from both lakes, a marked change in vegetation from closed forests with swamp elements to open flooded savanna at c. 5000 yrbpwas evident from the pollen record. Charcoal analysis revealed a pattern of increased accumulation of charred particles coincident with the establishment of savanna vegetation, suggesting higher fire frequency near the lakes. Because the timing of the sedimentary hiatus overlapped with the highest Holocene sea level, which would have increased the local water table preventing the lakes from drying out, we infer that both lakes used to depend heavily on flood waters, and the sedimentary gap was caused by reduced discharge from the Amazon River, due to a dry period in the Andes, when precipitation levels markedly decreased between 8000 and 5000 yrbp. The lack of Andean pollen (probably river transported) in the sediment record after this event and the existence of similar records near the study site make this interpretation more appealing. The resumption of sedimentation in Lake Marcio, contemporaneous with falling sea level and increasingly wet conditions in the Andes after 5000 yrbp, indicates that Holocene sea-level variation did not play an important role in maintaining lake levels. Main conclusions 

The study site recorded long-term occupation by pre-Columbian peoples. However, it is still unclear whether these disjoint savannas have an anthropogenic origin. Even though locally dry environmental conditions were inferred from both records, there is no evidence of a mid-Holocene dry climate in eastern Amazonia. Instead, the Amapá record indicates a connection between Andean climate and eastern Amazonia, demonstrating the need for a better understanding of the impacts and magnitude of climate changes.
No References
No Citations
No Supplementary Data
No Data/Media
No Metrics

Keywords: Amazonia; Amazonian savannas; charcoal; climate change; environmental change; palaeoecology; pollen analysis

Document Type: Research Article

Publication date: 2007-08-01

  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
X
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more