Impacts of shaded agroforestry management on carbon sequestration, biodiversity and farmers income in cocoa production landscapes

Purpose: Conversion of shaded agroforests to unshaded monocultures endangers the resilience of tropical landscapes. Landscape-scale impacts of alternative shade managements have rarely been assessed. This study explored plantation- and landscape-level impacts of different shade management strategies on aboveground biomass, functional group diversity, and economic potential of cocoa production in northern Ecuador. Methods: We simulated several cocoa shade management scenarios, using the dynamic forest model LANDIS-II: (i) ‘baseline’ projections representing the current mosaic of traditional agroforests, planted agroforests, and unshaded monoculture plantations; (ii) ‘traditional’ agroforestry shaded by native fruit and timber trees; (iii) ‘planted’ agroforests shaded by planted fruit trees; and (iv) ‘monoculture’ unshaded plantations. The impacts of setting aside 20, 30, and 40% of cocoa plantations for natural regeneration was tested for the monoculture scenario. Results: Traditional agroforests shaded by native trees stored up to 7% more aboveground biomass and had higher abundances of rare functional groups compared to monocultures after 50 years of simulation. Smaller effects were found for planted agroforests. Shaded plantations and land set aside for natural regeneration reduced forest fragmentation at the landscape level. The estimated yield gap for monoculture and shaded plantations could not be compensated by additional revenues for carbon storage at current carbon market price. Conclusions: Improving payment-for-ecosystem services and certification schemes are needed to incentivize smallholders to maintain substantial non-cocoa tree cover that may provide an environmental-friendly way to improve economic potential and food security for smallholders, while supporting biomass and functional group diversity at the landscape level.