Characterizing Fire Regimes of Northwest African Savannas From the Last Glacial Maximum to the Late Holocene
Abstract
Fire plays a crucial role in the ecology of many ecosystems and the release of both greenhouse gases and aerosols from combustion affect climate both regionally and globally. African savanna ecosystems are among the most burned on Earth with fires in these systems reflecting complex relationships and feedbacks with climate and vegetation. Accurate projections of future wildfire behavior require a wholistic understanding of how these relationships may have changed over time under varying climate states. Here we evaluate these fire-climate-vegetation relationships in Northwest African savannas from the last glacial maximum (LGM) to late Holocene. Here we use pyrosugars and polycyclic aromatic hydrocarbons (PAHs) to generate new records of low intensity and high intensity fires respectively from marine core OCE437-7 GC68 (~19°N). By normalizing these fire biomarkers to terrestrial plant waxes (n-alkanes) we reconstruct changes in fire relative to ecosystem biomass. We compare these fire histories with previously published estimates of savanna ecosystem composition (δ13Cwax), rainfall (δDPrecip), atmospheric CO2, and records of human occupation to explore the environmental and anthropogenic drivers of biomass burning. We find that rainfall is the dominant natural control on both high and low intensity fires within savanna ecosystems, with increased drought leading to greater combustion of biomass by fires. Any effects of temperature and vegetation composition are not apparent and must be small relative to the effect of rainfall. After ~8.7 ka fire intensities decline substantially despite late Holocene drying. We suggest that expanded human land-use for cultivation in the mid to late Holocene led to increased fuel fragmentation and suppression of high intensity fires.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFMPP15C..04O