Aboveground and belowground tree biomass and carbon stocks in the miombo woodlands of the Copperbelt in Zambia

Background

Miombo Woodlands occupy an estimated 2.7 million km² across southern Africa and support millions of people through fuelwood, charcoal, and non-timber products, while also storing substantial carbon. In Zambia’s Copperbelt Province, woodland conversion and degradation for charcoal and agriculture risk reducing carbon stocks, but local biomass values are poorly constrained, leading to uncertainty in national estimates and REDD+ baselines. This study responds to the need for site-specific biomass and carbon data in one of Zambia’s most industrialized and heavily used miombo regions.

Goals and Methods

This research quantifies aboveground and belowground tree biomass and carbon stocks in Copperbelt Miombo and examines variation across stand conditions. The authors established a network of fixed area plots (typically 20 × 20 or 25 × 25 m each), measured diameter at breast height and tree height, and use region-specific allometric equations to estimate per-tree and per-hectare biomass. They derive belowground biomass from root-to-shoot ratios and convert total biomass to carbon stocks using a standard carbon fraction (around 0.47–0.50), yielding Mg C ha⁻¹ values that can be scaled to the landscape level.

Conclusions and Takeaways

This study finds that intact Miombo Woodland in the Copperbelt can store on the order of 60–120 Mg C ha⁻¹ aboveground, with belowground pools adding roughly 20–30% to total tree carbon stocks, depending on site and disturbance history. Degraded or heavily used stands show substantially lower carbon densities, demonstrating that unsustainable harvesting can halve local carbon stocks relative to better-managed sites. The authors recommend that Zambia’s greenhouse gas inventory and REDD+ activities incorporate these empirical values into Copperbelt miombo management and prioritize management options that maintain or restore high-carbon stands over thousands of hectares of woodland.