117-8 Slow Vegetation Recovery Following an Unprecedented Afroalpine Wildfire in the Rwenzori Mountains, Uganda: Implications for Interpreting Paleofire-Vegetation Records

Abstract:

Wildfires are increasing in frequency and severity worldwide, raising questions about how rapidly ecosystems will respond to disturbance under a changing climate. In 2012, a wildfire burned approximately 42 km²  of the Afroalpine zone within the Rwenzori Mountains, Uganda, which was found to be the first fire in the area since deglaciation about 13.2 ka, and was linked to subsequent destructive downstream flooding and landslides. Here, we investigate the ecological response and regional sedimentary signature of this event using pollen and charcoal records from three lakes within and outside the burn area: Lower Kitandara Lake (outside the primary burn area), Lake Kopello (upper burned catchment), and Lake Africa (burned mid-catchment). All lakes showed an increase in macrocharcoal of an order of magnitude above pre-fire baselines.  At Lake Africa, this event was accompanied by elevated microcharcoal concentrations that persisted through an extended sediment interval from 21-10 cmblf. At Lake Africa, a new ²¹⁰Pb chronology, and reduced pollen concentrations above the base of the macrocharcoal peak, indicate substantially increased sediment influx following the fire, suggesting prolonged post-fire erosion and charcoal transport into the basin. Vegetation-fire responses suggest that endemic plants associated with the flat boggy valley floors surrounding Lake Africa declined markedly following the fire. In contrast, dominant woody taxa, including Dendrosenecio and ericaceous heath, showed little persistent change, despite visible and extensive fire damage in the modern landscape. However, multivariate analysis indicates distinct pre-fire, disturbance, and post-fire communities, suggesting that although the ecosystem has undergone substantial recovery during the twelve years since the fire, it has not yet returned to its pre-fire state. Combined with long-term Holocene records of pollen and charcoal from these sites, our results demonstrate that, not only was the 2012 wildfire unprecedented within at least 13.2 kyrs, but also that vegetation recovery following these events is slow and accompanied by significant reorganization of lacustrine deposition.

Geological Society of America Abstracts with Programs. Vol. 58, No. 5, 2026

doi: 10.1130/abs/2026AM-18624

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