Fire activity in tropical ecosystems since the Last Glacial Maximum: an
assessment based on synthesis and analysis of charcoal data
Power, Mitchell J.1†, Mayle, Francis1, and IGBP Paleofire FTI
Participants2
Institute of Geography, School of Geosciences, University of Edinburgh,
Drummond Street, Edinburgh, EH8 9XP
1
2
Initiative sponsored by the International Geosphere Biosphere Program Fast
Track Initiative on Fire, coordinated by QUEST (Quantifying Uncertainties in
the Earth System) a directed program of the UK Natural Science Research
Council. Over 60 scientists have contributed to this project.
Fire is one of the most important natural disturbances in tropical ecosystems
and greatly contributes to global carbon dioxide and methane emissions. The
role of paleofire activity in tropical South and Central America since the Last
Glacial Maximum (LGM) is assessed from a regional synthesis of sedimentary
charcoal records. In this research paleofire activity is presented at 500-year
time slices for tropical Central and South America as anomalies from present.
Across this region, fire activity was lower-than-present during the LGM, but
became greater than present by 19,000 cal yr BP. After 19,000 cal yr BP, fire
activity decreased to anonymously low values by 13,500 cal yr BP. After
13,500 cal yr BP, fire activity increased, reaching higher-than-present values
by 10,000 cal yr BP. After 10,000 cal yr BP fire activity decreased to near
modern values during the early-to-middle Holocene. During the late
Holocene, between 5000 to 3000 cal yr BP, fire activity once again increased
to higher-than-present values across the region. These data suggest that fire
activity has varied through time in tropical ecosystems. Regional coherency
in the timing of increased and decreased fire activity across a variety of site
types, investigated with a variety of sampling methodologies, suggest tropical
biomass burning is at least partly controlled by orbital forcing and large-scale
climatic drivers. Spatial heterogeneity in the paleofire records suggests
biomass (e.g. rainforest versus savannas) and human activity may also be
significant controls of fire activity. These results offer a useful validation tool
for climate modellers attempting to understand the role of future tropical
biomass burning in relation to global carbon dioxide and methane emissions.
†
Corresponding author: email Mitch.Power@ed.ac.uk