Developing an Original Paleoecological Framework for Reconstructing Late Quaternary Vegetation History and Human Influence in the Lower Niger Valley, Nigeria

The vegetational history of the Lower Niger Valley during the Late Quaternary, encompassing the last 30,000 years, and the role of human land use in modifying this history before the historic period, remain among the most significant unresolved questions in West African paleoecology, and this study addresses them through an original multi-proxy paleoecological framework. This study develops and applies an original multi-proxy paleoecological framework to reconstruct Late Quaternary vegetation history and disentangle natural climate forcing from early human landscape modification in the Lower Niger Valley of Anambra and Kogi States. Two sediment core sites were selected from oxbow lakes in the Lower Niger floodplain using geomorphological survey: Anambra Oxbow Core (AO-1) and Idah Swamp Core (IS-2). Core chronologies were established by AMS radiocarbon dating of 18 and 12 samples respectively, providing continuous records spanning the last 28,000 and 22,000 years. Multi-proxy analysis encompassed pollen, non-pollen palynomorphs, phytoliths, charcoal, and geochemical proxies (carbon and nitrogen isotopes, magnetic susceptibility). Pollen and phytolith data were calibrated against modern analogue datasets from 142 surface sediment samples collected from current vegetation communities. Phytolith assemblages from the earliest sediment horizons indicated open savanna vegetation coinciding with the Last Glacial Maximum. Rapid forest expansion at approximately 12,000 years before present correlated with the onset of the African Humid Period in the pollen record. An anomalous charcoal peak associated with disturbed pollen assemblages at approximately 4,500 years before present provides the first paleoecological evidence of sustained anthropogenic burning in the Lower Niger Valley. An original vegetation-human interaction model for the Niger Valley Holocene transition is proposed. The study makes a foundational original contribution to West African Late Quaternary paleoecology.

Keywords: paleoecology, Late Quaternary, vegetation history, Lower Niger Valley, multi-proxy analysis