Reconstructing Historical Forest Baselines and Degradation Trajectories in the Middle Belt Region Using Palaeoecological Methods

Effective forest restoration and policy design in the Nigerian Middle Belt region requires knowledge of pre-disturbance forest baselines that extend beyond the historical record accessible from satellite or aerial photography, yet palaeoecological data capable of providing these deep baselines are virtually absent for this zone. This study reconstructs historical forest baselines and degradation trajectories in the Middle Belt forest-savanna mosaic using pollen analysis, phytolith records, and charcoal stratigraphy from lake sediment cores and soil profiles across Benue, Plateau, and Kogi States. Sediment cores were extracted from five lake basins and three bog deposits, providing continuous records spanning two millennia at multiple sites. Pollen assemblages were identified to the lowest possible taxonomic resolution using reference collections established through modern pollen-trap surveys across the study region. Phytolith analysis complemented pollen data for reconstructing grass community composition and fire frequency. Charcoal influx provided a proxy for fire activity. Age models were constructed from AMS radiocarbon dates at each site. Results reveal that Guinea savanna woodland dominated the region until approximately 600 years before present, after which a progressive shift toward open savanna and grassland is documented, accelerating markedly in the past 150 years and consistent with intensified land use and climatic aridification. Pre-colonial forest extent was substantially greater than current vegetation maps suggest, with closed forest patches persisting along river corridors until the early colonial period. The study establishes empirical baselines for ambitious forest restoration targets in the Middle Belt and proposes a National Forest Restoration Reference Level derived from palaeoecological evidence. Keywords: palaeoecology, forest baseline, Middle Belt, pollen analysis, degradation trajectory