EXPLORING HIGH-RESOLUTION MID-HOLOCENE FIRE-CLIMATE LINKAGES IN THE HYPER BIODIVERSE FYNBOS, SOUTH AFRICA

Fire is a critical ecological force in southern Africa’s Cape Floristic Region (CFR), with many plants requiring fire for their reproductive success and development. Local managers must balance burning the ecosystem to promote vegetative health with the often-conflicting needs of the nearby wildlife and human populations. A detailed understanding of past burning activity and ecosystem recovery time following fire events in the CFR remains largely undocumented, presenting challenges for managing this system under a rapidly warming and drying climate. In this research, we use sedimentary charcoal influx (# of particles/cm²/year) at exceptionally high-resolution—approximately 2-year intervals—to reconstruct mid-Holocene burning activity at a coastal fynbos-afrotemperate forest ecotone lake, Eilandvlei, situated along South Africa’s southern Cape coast. Our resolution allows us to address fire on ecological timescales and to question how applicable our historical fire knowledge is to deeper time and dynamic climate and environmental changes in the fynbos. We explore how fire frequency and magnitude varies with local, regional and global changes in climate, and expect that fire regimes will change in response to shifts in the Westerlies, which enhances the flow of warm, Agulhas Current waters and increases moisture availability along the southern coast. Spectral data suggests that the mid-Holocene was characterized by higher charcoal influx and peak magnitudes from approximately 4,200 to 3,900 calibrated years BP, followed by comparably lower influx and peak magnitudes. This change in fire frequency may be linked to drought following the end of the African Humid Period and reflects other global and regional changes around 4,000 BP. This work is the first to leverage high-resolution sedimentary charcoal data in the fynbos and sets the stage for an improved understanding of the links between climate, people, vegetation, and fire in one of the world’s most biodiverse ecosystems.