The potential of plantations of Terminalia superba Engl. & Diels for wood and biomass production (Mayombe Forest, Democratic Republic of Congo)

Abstract

Abstract• In the 1940s-1950s, large limba (Terminalia superba Engl. & Diels) plantations were established in the Democratic Republic of Congo to reduce the pressure on the natural forests.• The objective of this study was to evaluate the potential of these long-rotation plantations as production forests (timber) and carbon sinks.• Five different plantations, between 50 and 58 years old, were sampled. Over a sample surface of more than 73 ha, the diameter above buttresses of 2 680 trees, bole height of 265 trees and tree height of 128 trees was measured.• To estimate the commercial volume, a nonlinear power law regression was used (R 2 = 0.95). A power law variance function was applied to counter heteroscedasticity of the residual plot. Estimates of commercial tree and stand volume at 50 to 58 y were 5.6 ± 4.1 m 3 and 183.9 ± 135.0 m 3 ha −1 . Stand volumes appear low but are explained by a large decrease in tree density. However, the mean volume increment of 3.2-3.7 m 3 ha −1 y −1 corresponds well with teak plantations of a similar age. For limba, aboveground biomass and carbon estimates of this study (resp. 108.4 and 54.2 Mg ha −1 ) differ significantly from those of existing aboveground biomass models (resp. 135.7-143.9 Mg ha −1 biomass and 67.9-72.0 Mg ha −1 C). All aboveground biomass and carbon estimates for T. superba stands were lower than for the estimates of young fast-growing plantations like Tectona grandis L. f., Eucalyptus spp. and Acacia spp. (≤ 30 y). Mots-clés :Terminalia superba / Afrique centrale / plantation / volume / biomasse Résumé -Le potentiel des plantations de Terminalia superba Engl. & Diels dans la production de bois et de biomasse (forêt de Mayombe, République Démocratique du Congo).• Dans les années 1940-1950, de grandes plantations de limba (Terminalia superba Engl. & Diels) on été mises en place en République Démocratique du Congo afin de réduire la pression sur les forêts naturelles.• L'objectif de cette étude était d'évaluer le potentiel de ces plantations anciennes comme forêts de production de bois d'oeuvre et puits de carbone.• Cinq plantations différentes, âgées de 50 à 58 ans, ont été échantillonnées. Sur une surface de plus de 73 ha, le diamètre au-dessus des contreforts de 2 680 arbres, la hauteur de fût de 265 arbres et la hauteur totale de 128 arbres ont été mesurés.• Le volume commercial a été estimé à l'aide d'une régression du type loi de puissance (R 2 = 0.95). Une fonction de variance du même type a été adoptée pour supprimer l'hétéroscedasticité des résidus. Le volume commercial a été estimé à 5.6 ± 4.1 m 3 par arbre et 183.9 ± 135.0 m 3 ha −1 . Ce dernier volume semble faible mais peut être expliqué par une chute de la densité d'arbres. Toutefois, l'accroissement moyen en volume (3,2-3,7 m 3 ha −1 an −1 ) correspond bien avec des plantations de teck d'un âge comparable. Pour le limba, il y a une différence significative entre les valeurs d'estimation de biomasse et de quantité de carbone épigés dans cette étude (resp. 108,4 Mg ha −1 et 54,2 Mg ha −1 ) et dans les...

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