CBOG data

Résumé fourni par la source

Background: Oak savanna at the ecotone between the Great Plains and the North American coniferous forests are often considered degraded forests, despite their origin in long-term interactions between vegetation, fire and climate. Few studies document their long-term fire history and development.Aims: This study reconstructs millennial-scale vegetation and fire dynamics to determine the role of fire in the establishment and maintenance of oak savanna ecosystems.Methods: Pollen and charcoal particles were retrieved from sediment cores collected at Cedar Bog Lake (Minnesota, USA). The obtained records were used to infer vegetation composition, fire frequency, and fuel types over the past 10,000 years.Key results: Three major vegetation phases were identified, including a transition from post-glacial boreal communities to pine–oak forests and, after 3800 cal BP, to a grass-dominated oak savanna ecosystem. Fire reconstructions indicate early infrequent high-biomass fires that shifted at 4800 cal BP towards more frequent, low-intensity fires dominated by herbaceous fuels.Conclusions: The establishment and persistence of oak savanna over the past five millennia were strongly linked to frequent, low-intensity fires.Implications: Post colonization fire suppression has disrupted the long-standing Indigenous fire-stewarship, highlighting the importance of ecologically informed prescribed burning to maintain ecosystem biodiversity and function.

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