Assessing Carbon Pools of Three Indigenous Agroforestry Systems in the Southeastern Rift-Valley Landscapes, Ethiopia

Abstract

The role of agroforestry (AF) systems in providing ecosystem services is very crucial. The greatest considerable increase in carbon (C) storage is often attained by moving from lower biomass land-use systems to tree-based systems such as AF. However, for estimation of C stocks in indigenous AF systems of southeastern Rift-Valley landscapes, Ethiopia, the data are scarce. This study was aimed to investigate the biomass, biomass carbon (BC), and soil organic carbon (SOC) stock of Enset-based, Enset-Coffee-based, and Coffee-Fruit-tree-Enset based AF systems. Comparison of SOC stock of AF systems against their adjacent monocrop farms was also investigated. Research questions were initiated to answer whether C stocks among the three AF systems vary because of different management systems and how biomass C stock is influenced by species abundance, diversity, and richness in the AF systems. The study was carried out at three selected sites in the Dilla Zuria district of Gedeo zone. Twenty farms (total of 60) representative of each AF system were arbitrarily selected and inventoried, and the biomass C stocks estimated. Ten adjacent monocrop farms which were related to each AF system were selected in a purposive manner for comparison of SOC stock. Inventory and soil sampling were employed in the 10 × 10 m farm plot. The mean AGB ranged from 81.1 to 255.9 t ha−1 and for BGB from 26.9 to 72.2 t ha−1. The highest C stock was found in Coffee–Fruittree–Enset based (233.3 ± 81.0 t ha−1), and the lowest was in Coffee–Enset based AF system (190.1 ± 29.8 t ha−1). The result showed that SOC stocks were not statistically significant between the three AF systems, although they showed a significant difference in their BC stock. The C stocks of the investigated AF systems are considerably higher than those reported for some tropical forests and AF systems. The SOC of AF systems is significantly higher than the ones for the adjacent monocrop farms. Therefore, it can be understood that the studied AF systems are storing significant amounts of C in their biomass as well as in soil. This considerable C storage by these systems might contribute to climate change mitigation.

Carbon Stock Assessment of Four Selected Agroforestry Systems in Owerri-West Local Government Area, Nigeria

“…The inventory was aimed to obtain data for the biomass estimation. The quadrats size in this study corroborate with previous work in the literature [2]. Within each quadrant, three 50 × 50 cm small plots for litter sampling were laid out.…”

“…They use mixed farming, including non-fruit trees, fruit trees, crops, vegetables, spices production, and very limited animal husbandry focused on, goats, piggery, and poultry". [6] Although there are several types of agroforestry systems practiced by the farmers, the main and most common which were used for this study were (1) Elaeis guineensis (oil palm tree) based agroforestry system (2) Irvingia gabonensis (bush mango) based agroforestry system and (3) Plantain (Musa paradisiaca) agroforestry system and (4) mixed multistory agroforestry system (Table 2). These agroforestry systems identified for sampling are located at Ndigwu, Obinze, Eziobodo and Avu / Umuguma.…”

“…"Agroforestry practice is seen as one of the greenhouse gas reduction strategies under the Kyoto Protocol, which was adopted in 1997. As a result, the sequestration potential of agroforestry systems has received attention by the global community and many countries are currently adopting the practice in their climate change mitigation strategy" [2,3].…”

“…"The capacity of agroforestry systems to store C differs across different agroecological landscapes". [6] Montagnini, and Nair, [7] reported that "storage potential for semiarid, subhumid, humid, and temperate regions was estimated at 9, 21, 50, and 63 t C ha −1 , respectively". Also extensive reviews were carried out by [8] for "West African countries (extending from Arid Sahara Desert to humid region Guinea) and they reported that biomass C stocks ranged from 22.2 to 70.8 t C ha −1" .…”

Estimating carbon stocks of three traditional agroforestry systems and their relationships with tree diversity and stand density

“…From an ecological aspect, agroforestry gives many advantages in increasing carbon stock and biodiversity (Hartoyo et al 2019b), as well as reducing climate change effects through carbon sequestration (Gebremeskel et al 2021;Subedi et al 2022). Tesfay et al (2022) explained that the agroforestry system stores carbon larger than seasonal or annual-based plant farming. The presence of various quality trees, which have high biomass and high input of litter continuously.…”