Carbon sequestration in trees and soil in natural and assisted reforestation on the Ibi Village Bateke plateau, Democratic Republic of the Congo

RESUME

Savannas cover about 76.8 million hectares in the Democratic Republic of Congo (DRC) and are potential sinks for carbon sequestration, which may contribute to the fight against climate change and deforestation and generate carbon credits. Among the means to achieve a reduction in atmospheric CO2, carbon storage (Sink) in grass or shrub savannas is one solution promoted by international organizations including the Intergovernmental Panel on Climate Change (IPCC). As part of the IBI-Village carbon sink project, we have protected savannas of Bateke plateau against bushfire to determine the carbon sequestration rate. An indirect method based on tree allometric equations (dbh and height) was used to determine the stock of aboveground biomass (AGB). Sampling of soil horizons collected at different depths of soil profiles established according to an altitudinal gradient allowed the estimation of soil carbon stock. The main results are that the gallery forest showed an important reforestation averaging 107,477 t/ha of total biomass or 51,05 Mg C/ha (187,35 Mg CO2 equivalent /ha sequestered), in comparison with 103,772 t/ha of total biomass or 49,29 Mg C /ha (180,90 Mg CO2 equivalent /ha sequestered) in the forest island and 22,336 t/ha of total biomass or 10,60 Mg C/ha (38,93 Mg CO2 equivalent/ha) in the Acacia auriculiformis plantation. Defensiveness favors forest species, and thereby accelerates biomass production and thus carbon fixation. The ANOVA used to compare the biomass increments of forest series vs. savannah series has shown that forest series species have twice the biomass increments of savannah series species over the three years of exclusion fire.

Keywords : Biomass, Ibi-village, exclosure, reforestation, shrubland savannas, carbon sequestration.

Tolérant K. LUBALEGA, Isabelle ISUNGU, Énoch MUPWALA, Alphonse MABANGA, Damase P. KHASA, Jean-Claude RUEL, Hugo MAYIGU, Emmanuel Matangwa