Advanced search
1 file | 531.54 KB Add to list

Long-term variability and rainfall control of savanna fire regimes in equatorial East Africa

(2012) GLOBAL CHANGE BIOLOGY. 18(10). p.3160-3170
Author
Organization
Abstract
Fires burning the vast grasslands and savannas of Africa significantly influence the global carbon cycle. Projecting the impacts of future climate change on fire-mediated biogeochemical processes in these dry tropical ecosystems requires understanding of how various climate factors influence regional fire regimes. To examine climatevegetationfire linkages in dry savanna, we conducted macroscopic and microscopic charcoal analysis on the sediments of the past 25000years from Lake Challa, a deep crater lake in equatorial East Africa. The charcoal-inferred shifts in local and regional fire regimes were compared with previously published reconstructions of temperature, rainfall, seasonal drought severity, and vegetation dynamics to evaluate millennial-scale drivers of fire occurrence. Our charcoal data indicate that fire in the dry lowland savanna of southeastern Kenya was not fuel-limited during the Last Glacial Maximum (LGM) and Late Glacial, in contrast to many other regions throughout the world. Fire activity remained high at Lake Challa probably because the relatively high mean-annual temperature (approximate to 22 degrees C) allowed productive C4 grasses with high water-use efficiency to dominate the landscape. From the LGM through the middle Holocene, the relative importance of savanna burning in the region varied primarily in response to changes in rainfall and dry-season length, which were controlled by orbital insolation forcing of tropical monsoon dynamics. The fuel limitation that characterizes the region's fire regime today appears to have begun around 5000-6000years ago, when warmer interglacial conditions coincided with prolonged seasonal drought. Thus, insolation-driven variation in the amount and seasonality of rainfall during the past 25000 years altered the immediate controls on fire occurrence in the grass-dominated savannas of eastern equatorial Africa. These results show that climatic impacts on dry-savanna burning are heterogeneous through time, with important implications for efforts to anticipate future shifts in fire-mediated ecosystem processes.
Keywords
SOUTHERN AFRICA, CARBON EMISSIONS, GLACIAL TREES, LATE HOLOCENE, LAKE RUTUNDU, fuel limitation, Quaternary, savanna, seasonality, BREA TAR PITS, ATMOSPHERIC CO2, INTERANNUAL VARIABILITY, MULTIVARIATE-ANALYSIS, CLIMATE DYNAMICS, grassland, fire, charcoal, C4 grasses, Africa, drought

Downloads

  • (...).pdf
    • full text
    • |
    • UGent only
    • |
    • PDF
    • |
    • 531.54 KB

Citation

Please use this url to cite or link to this publication:

MLA
Nelson, David M, Dirk Verschuren, Michael A Urban, et al. “Long-term Variability and Rainfall Control of Savanna Fire Regimes in Equatorial East Africa.” GLOBAL CHANGE BIOLOGY 18.10 (2012): 3160–3170. Print.
APA
Nelson, D. M., Verschuren, D., Urban, M. A., & Hu, F. S. (2012). Long-term variability and rainfall control of savanna fire regimes in equatorial East Africa. GLOBAL CHANGE BIOLOGY, 18(10), 3160–3170.
Chicago author-date
Nelson, David M, Dirk Verschuren, Michael A Urban, and Feng Sheng Hu. 2012. “Long-term Variability and Rainfall Control of Savanna Fire Regimes in Equatorial East Africa.” Global Change Biology 18 (10): 3160–3170.
Chicago author-date (all authors)
Nelson, David M, Dirk Verschuren, Michael A Urban, and Feng Sheng Hu. 2012. “Long-term Variability and Rainfall Control of Savanna Fire Regimes in Equatorial East Africa.” Global Change Biology 18 (10): 3160–3170.
Vancouver
1.
Nelson DM, Verschuren D, Urban MA, Hu FS. Long-term variability and rainfall control of savanna fire regimes in equatorial East Africa. GLOBAL CHANGE BIOLOGY. 2012;18(10):3160–70.
IEEE
[1]
D. M. Nelson, D. Verschuren, M. A. Urban, and F. S. Hu, “Long-term variability and rainfall control of savanna fire regimes in equatorial East Africa,” GLOBAL CHANGE BIOLOGY, vol. 18, no. 10, pp. 3160–3170, 2012.
@article{4091934,
  abstract     = {Fires burning the vast grasslands and savannas of Africa significantly influence the global carbon cycle. Projecting the impacts of future climate change on fire-mediated biogeochemical processes in these dry tropical ecosystems requires understanding of how various climate factors influence regional fire regimes. To examine climatevegetationfire linkages in dry savanna, we conducted macroscopic and microscopic charcoal analysis on the sediments of the past 25000years from Lake Challa, a deep crater lake in equatorial East Africa. The charcoal-inferred shifts in local and regional fire regimes were compared with previously published reconstructions of temperature, rainfall, seasonal drought severity, and vegetation dynamics to evaluate millennial-scale drivers of fire occurrence. Our charcoal data indicate that fire in the dry lowland savanna of southeastern Kenya was not fuel-limited during the Last Glacial Maximum (LGM) and Late Glacial, in contrast to many other regions throughout the world. Fire activity remained high at Lake Challa probably because the relatively high mean-annual temperature (approximate to 22 degrees C) allowed productive C4 grasses with high water-use efficiency to dominate the landscape. From the LGM through the middle Holocene, the relative importance of savanna burning in the region varied primarily in response to changes in rainfall and dry-season length, which were controlled by orbital insolation forcing of tropical monsoon dynamics. The fuel limitation that characterizes the region's fire regime today appears to have begun around 5000-6000years ago, when warmer interglacial conditions coincided with prolonged seasonal drought. Thus, insolation-driven variation in the amount and seasonality of rainfall during the past 25000 years altered the immediate controls on fire occurrence in the grass-dominated savannas of eastern equatorial Africa. These results show that climatic impacts on dry-savanna burning are heterogeneous through time, with important implications for efforts to anticipate future shifts in fire-mediated ecosystem processes.},
  author       = {Nelson, David M and Verschuren, Dirk and Urban, Michael A and Hu, Feng Sheng},
  issn         = {1354-1013},
  journal      = {GLOBAL CHANGE BIOLOGY},
  keywords     = {SOUTHERN AFRICA,CARBON EMISSIONS,GLACIAL TREES,LATE HOLOCENE,LAKE RUTUNDU,fuel limitation,Quaternary,savanna,seasonality,BREA TAR PITS,ATMOSPHERIC CO2,INTERANNUAL VARIABILITY,MULTIVARIATE-ANALYSIS,CLIMATE DYNAMICS,grassland,fire,charcoal,C4 grasses,Africa,drought},
  language     = {eng},
  number       = {10},
  pages        = {3160--3170},
  title        = {Long-term variability and rainfall control of savanna fire regimes in equatorial East Africa},
  url          = {http://dx.doi.org/10.1111/j.1365-2486.2012.02766.x},
  volume       = {18},
  year         = {2012},
}

Altmetric
View in Altmetric
Web of Science
Times cited: