Browsing by Autor "Ezequiel Chavez"

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A 45kyr palaeoclimate record from the lowland interior of tropical South America
(Elsevier BV, 2011) Bronwen S. Whitney; Francis E. Mayle; Surangi W. Punyasena; Katharine Anne Fitzpatrick; Michael J. Burn; René Guillén; Ezequiel Chavez; David G. Mann; R. Toby Pennington; Sarah E. Metcalfe
A Satellite Model of Forest Flammability
(Springer Science+Business Media, 2013) Marc K. Steininger; Karyn Tabor; Jennifer Small; Carlos Pinto; Johan Soliz; Ezequiel Chavez
Differing local‐scale responses of Bolivian Amazon forest ecotones to middle Holocene drought based upon multiproxy soil data
(Wiley, 2023) James Hill; Stuart Black; Daniel P. Soto; Ezequiel Chavez; Vincent Antoine Vos; Francis Mayle
ABSTRACT Uncertainty remains over local‐scale responses of ecotonal Amazonian forests to middle Holocene drying due to the scarcity, and coarse spatial resolution, of lacustrine pollen records. This paper examines the palaeoecological potential of soil phytoliths, stable carbon isotopes and charcoal for capturing local‐scale ecotonal responses of different types of Bolivian Amazonian forest to middle Holocene climate change. Soil pits 1 m deep were dug at ecotones between rainforest, dry forest, Chaco woodland and savannah, and sampled at 5–10 cm resolution. Both phytolith and stable carbon isotope records indicate stability of dry forest–savannah ecotones over the last ca. 6000 years, despite middle Holocene drought, revealing the dominance of edaphic factors over climate in controlling this type of ecotone. In contrast, δ 13 C data reveal that rainforest–savannah ecotones were more responsive to climate change, with rainforest likely replaced by drought‐tolerant dry forest or savannah vegetation during the mid‐Holocene, consistent with regional‐scale lacustrine pollen records. However, such shifts are not apparent in most of our phytolith records due to insufficient taxonomic resolution in differentiating rainforest from dry forest. Charcoal data show that ecotonal dry forests experienced greater fire activity than rainforests and that recent high fire activity at all forest sites is unprecedented since at least the middle Holocene.
Localised land-use and maize agriculture by the pre-Columbian Casarabe Culture in Lowland Bolivia
(SAGE Publishing, 2025) Joseph Hirst; Marco F. Raczka; Umberto Lombardo; Ezequiel Chavez; Lorena Becerra‐Valdivia; McKenzie R. Bentley; Christopher Bronk Ramsey; Miros Stavros James Charidemou; Suzanne Maclachlan; Francis E. Mayle
Multiple pre-Columbian (pre-1492 CE) archaeological sites now challenge the traditional portrayal of Amazonia as a ‘pristine wilderness’. This is especially true within the forest-savanna mosaic landscapes of lowland Bolivia, where the pre-Columbian Casarabe Culture constructed hundreds of settlement mounds, integrated with a dense causeway-canal network – one of the most complex, stratified societies yet discovered in Amazonia. Excavations at previous sites indicate that this culture sustained itself by practicing large-scale, maize-based agriculture. However, the Casarabe Culture’s mounds have also been found within the riparian forests abutting major river systems, where their inhabitants could have benefitted from greater access to forest resources and local fish species. To determine whether these differences influenced how the Casarabe Culture utilised the landscape, we conducted palaeoecological analysis on the sediments collected from Laguna Loma Suarez (LLS), an oxbow lake situated adjacent to a monumental habitation mound within these riparian forests. Our analysis reveals that, despite significant differences in natural resource availability, the Casarabe Culture continued to cultivate maize locally around LLS for over a millennium, between 280 BCE and 1130 CE, with anthropogenic fires largely restricted to the open savannas. Our record also suggests that the Casarabe Culture possibly delayed either forest recovery or natural forest encroachment until after the nearby settlement mound was abandoned. These findings, when compared with those of other sites in the region, show that maize was an important crop in pre-Columbian times, irrespective of major differences in natural resource availability across the complex forest-savanna mosaic settings of Amazonian Bolivia.
Sensitivity of Bolivian seasonally-dry tropical forest to precipitation and temperature changes over glacial–interglacial timescales
(Springer Science+Business Media, 2013) Bronwen S. Whitney; Francis E. Mayle; Michael J. Burn; René Guillén; Ezequiel Chavez; R. Toby Pennington