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Provedor de dados:  5
País:  France
Título:  Orbital-scale climate forcing of grassland burning in southern Africa
Autores:  Daniau, Anne-laure
Goni, Maria Fernanda Sanchez
Martinez, Philippe
Urrego, Dunia H.
Bout-roumazeilles, Viviane
Desprat, Stephanie
Marlon, Jennifer R.
Data:  2013-03
Ano:  2013
Resumo:  Although grassland and savanna occupy only a quarter of the world's vegetation, burning in these ecosystems accounts for roughly half the global carbon emissions from fire. However, the processes that govern changes in grassland burning are poorly understood, particularly on time scales beyond satellite records. We analyzed microcharcoal, sediments, and geochemistry in a high-resolution marine sediment core off Namibia to identify the processes that have controlled biomass burning in southern African grassland ecosystems under large, multimillennial-scale climate changes. Six fire cycles occurred during the past 170,000 y in southern Africa that correspond both in timing and magnitude to the precessional forcing of north-south shifts in the Intertropical Convergence Zone. Contrary to the conventional expectation that fire increases with higher temperatures and increased drought, we found that wetter and cooler climates cause increased burning in the study region, owing to a shift in rainfall amount and seasonality (and thus vegetation flammability). We also show that charcoal morphology (i.e., the particle's length-to-width ratio) can be used to reconstruct changes in fire activity as well as biome shifts over time. Our results provide essential context for understanding current and future grassland-fire dynamics and their associated carbon emissions.
Tipo:  Text
Idioma:  Inglês

Editor:  Natl Acad Sciences
Formato:  application/pdf
Fonte:  Proceedings Of The National Academy Of Sciences Of The United States Of America (0027-8424) (Natl Acad Sciences), 2013-03 , Vol. 110 , N. 13 , P. 5069-5073
Direitos:  2013 National Academy of Sciences.


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