Allometry and Aboveground Biomass of Acacia auriculiformis A. Cunn.ex Benth Based Agroforestry Systems in Yangambi Landscape, Democratic Republic of Congo

Abstract

Most of the population living near the Yangambi Biosphere Reserve lives mainly from slash-and-burn agriculture which causes deforestation. The agroforestry system (AFS) is reputed to stabilise agriculture, store carbon in plant biomass and in the soil, and improve soil fertility. Acacia auriculiformis is a fast-growing leguminous tree that has been planted in AFS in the Yangambi landscape, but few or no studies assessed its aboveground biomass storage. This study aims to determine the aboveground biomass storage of AFS-based Acacia auriculiformis when intercropped with cassava, maise, and peanut food crops at different tree planting densities in the Yangambi landscape. The experimental device is a multifactorial trial of 36 plots of 400 m2 each one; with 4 treatments and 3 repetitions for each of these tree species in association with maise, groundnut, and cassava. Therefore, for assessing the aboveground biomass, the stem circumference and tree height were taken in each plot. Moreover, to study the A. auriculiformis allometry, 30 trees were cut and the aboveground biomass was estimated from the local allometric model set up in this study. Through this work, we have developed the three best allometric models for estimating the aboveground biomass of A. auriculiformis. The result showed that the aboveground biomass of A. auriculiformis varies between 0.49 and 10.54 t/ha (0.25 to 5.27 t/ha of carbon) depending on tree planting density and food crops. By comparing the results of the current study with those of others who worked on A. auriculiformis biomass, it was noted that the local models developed in this study contribute to increasing the precision of carbon estimation in the Congo basin. This is important for the implementation of REDD+ projects (Reducing emissions from deforestation and forest degradation) in the DRC. In conclusion, agroforestry plantations contribute to storing carbon in plant biomass.