Soil Organic Matter, Mitigation of and Adaptation to Climate Change in Cocoa–Based Agroforestry Systems

Abstract

Belowground roles of agroforestry in climate change mitigation (C storage) and adaptation (reduced vulnerability to drought) are less obvious than easy-to-measure aspects aboveground. Documentation on these roles is lacking. We quantified the organic C concentration (Corg) and soil physical properties in a mountainous landscape in Sulawesi (Indonesia) for five land cover types: secondary forest (SF), multistrata cocoa–based agroforestry (CAF) aged 4–5 years (CAF4), 10–12 years (CAF10), 17–34 years (CAF17), and multistrata (mixed fruit and timber) agroforest (MAF45) aged 45–68 years. With four replicate plots per cover type, we measured five pools of C-stock according to IPCC guidelines, soil bulk density (BD), macro porosity (MP), hydraulic conductivity (Ks), and available water capacity of the soil (AWC). The highest C-stock, in SF, was around 320 Mg ha−1, the lowest, 74 Mg ha−1, was in CAF4, with the older agroforestry systems being intermediate with 120 to 150 Mg ha−1. Soil compaction after forest conversion led to increased BD and reduced MP, Ks, and AWC. Older agroforestry partly recovered buffering: AWC per m of rooted soil profile increased by 5.7 mm per unit (g kg−1) increase of Corg. The restored AWC can support about a week’s worth of evapotranspiration without rain, assisting in climate change adaptation.

Carbon Sequestration Potential of Agroforestry Systems in Degraded Landscapes in West Java, Indonesia

“…RACSA can reduce time and expense, and is considered more effective [46,47]. Several previous studies have used this method to estimate carbon stock in agroforestry systems [46,48]. The components measured were tree biomass, understory biomass, woody necromass, and non-woody necromass (litter).…”

Rehabilitation and renovation of cocoa (Theobroma cacao L.) agroforestry systems. A review

“…Adoption of climate-smart cocoa farming strategies and practices that simultaneously address (at least) profitability, resilience and low GHG emissions is much needed. Farm diversification, agroforestry, the use of improved genotypes of both cocoa and associated crops, irrigation, fertilisation, soil organic matter and cover, integrated pest management, intensification and other good crop husbandry practices have all been recommended as key adaptation and mitigation measures to cope with climate change (Gusli et al 2020;Denkyirah et al 2017;Jagoret et al 2012). The use of shade trees (i.e.…”

Agroforestry-Based Ecosystem Services

“…Belowground roles of agroforestry in climate change mitigation (C storage) and adaptation (reduced vulnerability to drought) are less obvious than easy-to-measure aspects aboveground. Comparisons between cocoa agroforestry systems, intermediate in properties between remnant forest, and cocoa monocultures [2] showed that increased soil organic matter content can support about a week's worth of evapotranspiration without rain, assisting in climate change adaptation. Agroforestry systems in Viet Nam were also found to be intermediate between natural forest and cropland in terms of earthworm diversity [3].…”