Abstract
The environmental changes and the dynamics of the savanna-forest mosaic, over the last 1050 years, have been reconstructed by pollen, charcoal, radiocarbon dating mineralogical and geochemical analyses of sediment cores taken from three different Mauritia flexuosapalm swamps in the northernmost part of the Brazilian Amazon region (northern state of Roraima). Studies on the relationship between the modern pollen rain and the regional vegetation provide additional information for the interpretation of the fossil pollen records. The fossil pollen assemblages and geochemical results indicate relatively wet climatic conditions throughout the recorded period. Despite these moist conditions, fires were frequent and are one of the reasons for the dominance of a grassy savanna instead of forest expansion in the study area. Considering the generally wet climatic conditions, these fires were most likely caused by human activities. Even today, fires hinder forest expansion into savanna areas. Sandy hydromorphic soils may also act as an edaphic control to maintain the current sharp boundary between forest and savanna ecosystems.
Highlights
The northern and northeastern parts of the state of Roraima are located in the northernmost region of the Brazilian Amazon basin
The environmental changes and the dynamics of the savanna-forest mosaic, over the last 1050 years, have been reconstructed by pollen, charcoal, radiocarbon dating mineralogical and geochemical analyses of sediment cores taken from three different Mauritia flexuosa palm swamps in the northernmost part of the Brazilian Amazon region
The integrated pollen and sedimentological records show that wet conditions prevailed during the last 1050 years at sites Amajari (AM) and Maloca do Boqueirão (MB)
Summary
The northern and northeastern parts of the state of Roraima are located in the northernmost region of the Brazilian Amazon basin. The history of the savannas located north of the Amazon basin, is still poorly known despite an increasing number of publications during recent years. Most of the records concerning the history of the savanna are located in the Llanos Orientales in Colombia (Behling and Hooghiemstra 1998, 1999, 2000, Berrio et al 2000, 2002, Wille et al 2003) and in the Gran Sabana of Venezuela Pollen evidence from several savanna lake cores of the Llanos Orientales in Colombia, indicate an expansion of forest over savanna areas since about 4000 cal yr BP (Behling and Hooghiemstra 1998, 1999, 2000, Berrio et al 2000). Isotopic studies carried out in the southern Brazilian Amazon basin (Pessenda et al 1998, Freitas et al 2001, Behling 2002b) suggest a similar forest expansion during the same period
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
