Quantification of deadwood biomass, carbon stock, and carbon dioxide equivalent across decay classes along the Sobe road dualization corridor, Nigeria

Abstract

Deadwood constitutes an important yet frequently overlooked carbon pool in tropical forest ecosystems, contributing significantly to carbon storage and climate change mitigation. This study quantified deadwood biomass, carbon stock, and carbon dioxide equivalent (CO₂e) across three decay classes (Sound, Intermediate, and Rotten) along the Sobe road dualization corridor in Edo State, Nigeria. Using a stratified systematic sampling design, 55 coarse woody debris samples were measured for diameter, length, basal area, and volume. Biomass was estimated using decay-adjusted wood density, while carbon stock and CO₂e were calculated following IPCC guidelines. Sound deadwood recorded the highest mean biomass (0.824 ± 0.645 kg ha⁻¹), carbon stock (0.392 kg C ha⁻¹), and CO₂e (1.440 kg CO₂e ha⁻¹), whereas rotten wood exhibited the lowest values due to advanced decomposition. Biomass differences among decay classes were highly significant. Deadwood volume demonstrated an almost perfect positive relationship with carbon stock, indicating that volume is a reliable predictor of carbon storage. The findings emphasize the importance of incorporating decay-class-specific deadwood assessments into forest carbon inventories, Monitoring, Reporting and Verification systems, and climate mitigation initiatives to improve carbon accounting accuracy in disturbed tropical landscapes.

Keywords: Deadwood, Carbon Stock, Coarse Woody Debris, Carbon Accounting, Tropical Forest, Climate Change Mitigation, CO₂ Equivalent