Are traditional agroforestry systems nature-based carbon sinks? Empirical evidence from Tanzania
摘要
Traditional agroforestry systems (TAFS) are increasingly recognized for their multifunctional roles in biodiversity conservation, livelihood support and climate change mitigation. However, empirical quantification of their carbon sequestration potential remains limited, particularly in sub-Saharan Africa. This study assessed the carbon storage capacity of three representative TAFS in Tanzania: Alalili (silvopastoral), Ngitili (agrosilvopastoral) and Faidherbia parkland (agrosilvicultural). Using standardized field measurements across 48 plots (20 m × 20 m), above- and below-ground biomass and carbon stocks were estimated through generalized allometric models. Results revealed significant differences (P < 0.05) among the systems, with total carbon stocks (TCS) ranging from 17.96 ± 3.64 Mg C ha⁻1 in Ngitili to 151.91 ± 10.71 Mg C ha⁻1 in Faidherbia parkland. Faidherbia parkland exhibited the highest carbon sequestration potential, attributed to the presence of large-diameter trees. Conversely, Ngitili, despite having a higher stem density, recorded the lowest TCS due to smaller tree sizes. These findings demonstrate that TAFS function as important nature-based carbon sinks, offering considerable opportunities for inclusion in climate change mitigation strategies such as REDD + initiatives and carbon farming schemes. Protecting and enhancing TAFS could yield co-benefits for carbon sequestration, biodiversity conservation and rural livelihoods. The study underscores the need for greater integration of TAFS into national climate policy frameworks and global carbon accounting systems.