Abstract
Fire regimes differ across tropical and subtropical biomes depending on multiple parameters whose interactions and levels of importance are poorly understood, particularly at multidecadal and longer time scales. In the catchment of Lake Victoria, savanna, rainforest, and Afromontane vegetation have interspersed over the last 17,000 years, which may have influenced the fire regime and vice versa. However, climate and humans are most often the primary drivers of fire regime changes, and analysing their respective roles is critical for understanding current and future fire regimes. Besides a handful of radiocarbon dates on grassy charcoal, the timescales of published studies of Lake Victoria sediment chronologies rely mostly on dates of bulk sediment, and chronological disagreements persist, mainly due to variation between estimations of the 14C reservoir effect. Here, we provide independent 14C chronologies for three Late Glacial and Holocene lacustrine sediment cores from various water depths and compare them with the biostratigraphy to establish a new chronological framework. We present the first continuous sedimentary charcoal records from Lake Victoria; these suggest that fire activity varied substantially during the past 17,000 years. Our new pollen records reveal the long-term vegetation dynamics. The available evidence suggests that before human impact increased during the Iron Age (ca. 2400 yr BP), biomass burning was linked to climate and vegetation reorganizations, such as warming, drying, and the expansion of rainforests and savannas. Our results imply that climate can trigger substantial fire regime changes and that vegetation responses to climate change can co-determine the fire regime. For instance, biomass burning decreased significantly when the rainforest expanded in response to increasing temperatures and moisture availability. Such insights into the long-term linkages between climate, vegetation, and the fire regime may help to refine ecosystem management and conservation strategies in a changing global climate.
| Original language | English (US) |
|---|---|
| Article number | 107915 |
| Journal | Quaternary Science Reviews |
| Volume | 301 |
| DOIs | |
| State | Published - Feb 1 2023 |
Bibliographical note
Funding Information:The authors Yunuén Temoltzin–Loranca, Giulia Wienhues, and Moritz Muschick were supported by SNSF Sinergia grant number 183566 awarded to Ole Seehausen, Martin Grosjean, Tom Gilbert, and Blake Matthews. The coring in Lake Victoria was financed by the strategic pool of the Faculty of Natural Sciences of University of Bern (grant to Ole Seehausen, Anna Sapfo Malaspinas, Willy Tinner, Oliver Heiri, Martin Grosjean, and Flavio Anselmetti) and the Institute of Plant Sciences of University of Bern . We gratefully acknowledge the coring leaders Petra Boltshauser-Kaltenrieder, Moritz Muschick, Salome Mwaiko, and Willi Tanner and the coring team members Sandra Brügger and Alexander Bolland. We thank Edith Vogel and Gary Salazar for their contribution to the 14 C analysis. We acknowledge the lab assistance of Lara Zinkl and Sara Brechbühl. We are deeply indebted to TAFIRI and its coring members for looking after the team and the coring platform during the expedition: Edwin Sombe (boat captain), Harith Kalima (engineer), Boaz Jumbe (crew), Toto Mohammed (technician), Daniel Bwathondi † (crew), Daniel Chacha (crew), and Hamisi Ramadhani (cook). We thank TAFIRI for all the logistic support during the campaign. This research was supported by TAFIRI and conducted under COSTECH research permit No. 2018-237-NA-2018-57 . We are grateful to Lisa Schüler for offering an introduction to East African pollen grains and for making available the pollen reference collection of the Mount Kilimanjaro area. Hermann Behling is gratefully acknowledged for hosting Yunuén Temoltzin-Loranca at the Department of Palynology and Climate Dynamics at the University of Göttingen. We thank Gianni Zanchetta and Richard Vachula for their careful reading of our manuscript and their insightful comments and suggestions.
Funding Information:
The authors Yunuén Temoltzin–Loranca, Giulia Wienhues, and Moritz Muschick were supported by SNSF Sinergia grant number 183566 awarded to Ole Seehausen, Martin Grosjean, Tom Gilbert, and Blake Matthews. The coring in Lake Victoria was financed by the strategic pool of the Faculty of Natural Sciences of University of Bern (grant to Ole Seehausen, Anna Sapfo Malaspinas, Willy Tinner, Oliver Heiri, Martin Grosjean, and Flavio Anselmetti) and the Institute of Plant Sciences of University of Bern. We gratefully acknowledge the coring leaders Petra Boltshauser-Kaltenrieder, Moritz Muschick, Salome Mwaiko, and Willi Tanner and the coring team members Sandra Brügger and Alexander Bolland. We thank Edith Vogel and Gary Salazar for their contribution to the 14C analysis. We acknowledge the lab assistance of Lara Zinkl and Sara Brechbühl. We are deeply indebted to TAFIRI and its coring members for looking after the team and the coring platform during the expedition: Edwin Sombe (boat captain), Harith Kalima (engineer), Boaz Jumbe (crew), Toto Mohammed (technician), Daniel Bwathondi † (crew), Daniel Chacha (crew), and Hamisi Ramadhani (cook). We thank TAFIRI for all the logistic support during the campaign. This research was supported by TAFIRI and conducted under COSTECH research permit No. 2018-237-NA-2018-57. We are grateful to Lisa Schüler for offering an introduction to East African pollen grains and for making available the pollen reference collection of the Mount Kilimanjaro area. Hermann Behling is gratefully acknowledged for hosting Yunuén Temoltzin-Loranca at the Department of Palynology and Climate Dynamics at the University of Göttingen. We thank Gianni Zanchetta and Richard Vachula for their careful reading of our manuscript and their insightful comments and suggestions.
Publisher Copyright:
© 2022 The Authors
Keywords
- Charcoal
- Chronology
- Fire
- Holocene
- Lake Victoria
- Late Pleistocene
- Pollen
- Radiocarbon
Continental Scientific Drilling Facility tags
- VICTORIA
