The degree to which the maintenance of carbon (C) stocks and tree diversity can be jointly achieved in production landscapes is debated. C stocks in forests are decreased by logging before tree diversity is affected, while C stocks in monoculture tree plantations increase, but diversity does not. Agroforestry can break this hysteresis pattern, relevant for policies in search of synergy. We compared total C stocks and tree diversity among degraded forest, complex cacao/fruit tree agroforests, simple shade-tree cacao agroforestry, monoculture cacao, and annual crops in the Konawe District, Southeast Sulawesi, Indonesia. We evaluated farmer tree preferences and the utility value of the system for 40 farmers (male and female). The highest tree diversity (Shannon–Wiener H index 2.36) and C stocks (282 Mg C ha−1) were found in degraded forest, followed by cacao-based agroforestry systems (H index ranged from 0.58–0.93 with C stocks of 75–89 Mg ha−1). Male farmers selected timber and fruit tree species with economic benefits as shade trees, while female farmers preferred production for household needs (fruit trees and vegetables). Carbon stocks and tree diversity were positively related (R2 = 0.72). Adding data from across Indonesia (n = 102), agroforestry systems had an intermediate position between forest decline and reforestation responses. Maintaining agroforestry in the landscape allows aboveground C stocks up to 50 Mg ha−1 and reduces biodiversity loss. Agroforestry facilitates climate change mitigation and biodiversity goals to be addressed simultaneously in sustainable production landscapes.
Tag: cocoa
Cocoa agroforest multifunctionality and soil fertility explained by shade tree litter traits
Manipulating plant functional diversity to improve agroecosystem multifunctionality is a central challenge of agricultural systems world‐wide. In cocoa agroforestry systems (cAFS), shade trees are used to supply many services to farmers, yet their impact on soil functioning and cocoa yields is likely to vary substantially among tree species. Here we compared the impact of five shade tree species (Canarium schweinfurthii (Canarium), Dacryodes edulis (Safou), Milicia excelsa (Iroko), Ceiba pentandra (Kapok tree), Albizia adianthifolia (Albizia)) and unshaded conditions on the functioning of poor sandy savanna soils within eight cocoa farms in Central Cameroon. We assessed the effects of plant functional traits, leaf litterfall and fine root biomass on a range of soil functions and on cocoa yield. Synthesis and applications. We demonstrate that cocoa agroforest multifunctionality is substantially influenced by the functional traits of shade tree species. Shade tree species with the most dissimilar traits to cocoa (cocoa showing the lowest leaf litter quality) showed the largest improvement of soil functions. Therefore, selection of shade trees based on their functional traits appears as a promising practice to adequately manage soil functioning. In order to fully assess the beneficial role of shade trees in these agroecosystems. Future research will need to extend this approach to other below‐ground traits and other aspects of multifunctionality such as long‐term cocoa health and yield.
Plant diversity and density in cocoa-based agroforestry systems: how farmers’ income is affected in the Dominican Republic
Cocoa-based agroforestry systems (AFS) provide a variety of products, either sold or self-consumed. The choice of crop species and planting density in cocoa AFS has an impact on the quantities and the economic value of the agricultural products sold and consumed by producers. We characterized 140 cocoa AFS in three main production areas in the Dominican Republic, together with farmer’s management practices, to construct a typology of cocoa AFS based on their structure, and evaluate their performances. The sum of the sales of cocoa, other products, and self-consumption did not differ significantly among AFS types. However, a high degree of diversification combined with a high density of associated fruit species reduced cocoa sales, but increased fruit sales and self-consumption. In contrast, a low diversity of associated plants including nitrogen-fixing trees increased cocoa sales but reduced fruit sales and self-consumption. The highest economic performance was obtained with intermediate diversity (three to seven species) and density (100–400 associated plants ha−1). Our results provide food for thought for optimizing crop diversity and density to adjust the economic balance between sales and self-consumption of the products harvested in cocoa AFS.
Avoidance of tree-site mismatching of modelled cacao production systems across climatic zones: Roots for multifunctionality
Protective roles of shade trees for climate-resilient cacao appear to depend on tree-site matching. Agroforestry practices involve a wide range of context-specific management options, which can be complex and pose challenges due to tradeoffs. To assess the benefits and drawbacks, across a range of contexts, of various cacao-based land use systems on multifunctionality and economic performance. We used the process-based Water, Nutrient and Light Capture in agroforestry systems (WaNuLCAS) model to assess the performance of five cacao-based land use systems (cacao monoculture, cacao + annual crops, cacao + fruit tree, cacao + fast-growing tree, and cacao + slow-growing tree), in three climate regimes (tropical rainforest, monsoon, and savannah), two soil textures, and two sources of data for cacao root length density (W Africa and Indonesia, respectively). Several metrics quantified the performance of each land use system, including the Land Equivalent Ratio for production (LERP),multifunctionality (LERM), Net Present Value (NPV), Return to Labour (RtL), and Benefit-Cost Ratio (BCR). Simulated cacao production per tree, positively or negatively influenced by intercrops, responded to the number of days cacao grew under water-limited conditions. High cacao root density supported higher LERP values (an average of 1.15 versus 0.95 in other cases). In the savanna, the LERP difference between cacao with high root density and those with low root density became 0.27. Among agroforestry systems, cacao + annual crops had the highest LERP of 1.13, followed by cacao + slow-growing trees (1.09), while the lowest outcome (0.98) was for cacao + fruit trees. These values were higher in rainforest climates, and lowest for savanna. Soil texture had no effect on the average LERP across other main factors. Tree-based agroforestry had a higher time-averaged carbon stock than monocultures or systems with annual crops. However, their effects on other environmental performance aspects, averaged over a 20-year life cycle, were modest, and variation in LERM was small. Economic performance indicators diverged, with the highest NPV were for cacao + annual crops or cacao + fruit trees, the highest BCR was for cacao + fruit trees, and the highest RtL was for cacao + fruit trees followed by cacao + slow-growing trees. Our study highlights that the potential benefits of cacao-based agroforestry practices depend on strong root development by the cacao trees. In selecting for high yields in monocultures, the benefits of intercropping may be forfeited, especially in drier climates with the lower values for root length density measured in W Africa.
The potential of agroforestry concessions to stabilize Amazonian forest frontiers: a case study on the economic and environmental robustness of informally settled small-scale cocoa farmers in Peru
Low-emissions and profitable cocoa through moderate-shade agroforestry: Insights from Ghana
Cocoa production is a leading driver of deforestation in the humid-tropics of West Africa. Reconciling climate change mitigation with livelihoods of farmers requires identification of production strategies to concurrently improve yield and profit while curtailing emissions of greenhouse gases (GHG). Using a 2021 plot-survey conducted in Ghana’s Eastern region, we evaluated yields, GHG emissions, and value of production (VOP) (a profit indicator) across a typology representing the diversity of systems at plot-level. The typology was constructed by first stratifying plots according to shade levels and variety (hybrid vs. Amazonia) which resulted in three systems: Hybrid sun, hybrid variety under full-sun (little to no shade); Hybrid shade, hybrid and moderate shade (13–25 shade trees ha−1); and Amazonia, Amazonia under predominantly moderate shade. Next, factor analysis and clustering were used to group plots within each system according to cocoa yield, vegetation, management, and (local) climate conditions. Cluster analysis showed that fertiliser, weeding, pruning, hand pollination, cocoa tree density, and shade tree densities of differing heights were most influential for determination across systems. Hybrid shade had the highest net GHG removal rate at −6.8 ± 1.7 (± 95% CI) Mg CO2eq ha−1 yr−1: 48% and 127% higher (emissions more negative) respectively over Amazonia and Hybrid sun. Hybrid shade additionally had the highest average and least variable VOP among production systems at 669 ± 564 USD ha−1 yr−1, compared to Hybrid sun and Amazonia at 404 ± 442 and 213 ± 280 USD ha−1 yr−1 respectively. These results point to hybrid cocoa grown under moderate shade of 13–25 shade trees ha−1 as optimal for reconciling climate change mitigation with development in West African cocoa.
Dynamics of soil organic carbon pools following conversion of savannah to cocoa agroforestry systems in the Centre region of Cameroon
Afforestation of gramineous-woody savannah with cocoa agroforestry systems (cAFS) is a common farmer practice in Cameroon considered as sustainable. Nevertheless, the effects of afforestation of savannah with cAFS on soil organic carbon (SOC) turnover and content, and the factors controlling SOC accumulation and stabilization are unknown. SOC content at 0–10 cm soil layer, and SOC distribution in soil particle size fractions (0–20 μm fraction considered as mineral-associated organic carbon, MAOC; 50–2000 μm considered as particulate organic carbon, POC; and 20–50 μm), were compared in different systems settled on degraded savannah (orthic ferralsols). These systems included annual cropland (≈ 5 years old), cocoa monoculture (≈10 years old), and cAFS (from 20 to 60 years old) including different shade tree species such as Albizia adianthifolia, Canarium schweinfurthii, Dacryodes edulis, Milicia excelsa and Ceiba pentandra. Savannah and nearby secondary forest patches were also included in the design as controls. Soil 13C was analysed to investigate the soil carbon turnover after afforestation (C3 plants) of gramineous savannah (C4 plants).
CACAOmustahan. Volume 03, Issue 01. January-March 2024
One of the key outputs of the Sustainable Farming in Tropical Asian Landscapes (SFITAL) project is a roadmap for sustainable cacao development in Davao de Oro. Since sustainable commodity development also related to other land uses over the landscape, World Agroforestry (ICRAF) applies a landscape approach and uses a spatially-explicit tool called R-FALLOW (Forest, Agroforestry, Low-value Land, or Waste?). R-FALLOW is used to assess economic-ecological trade-offs of various land-use scenarios. It takes into consideration local stakeholders—from decision makers to smallholder farmers—in terms of labor, allocation of land and finances for future land uses, aboveground carbon storage of the landscape, and possible land use changes in state-owned lands and forestlands.
Negative effects of water deficit on cocoa tree yield are partially mitigated by irrigation and potassium application
Yields of most tropical crops are strongly reduced by drought, but this may be partially mitigated by irrigation and potassium application. Understanding the mechanisms regulating these relationships is essential to select crop varieties reaching high yield under environmental stress. We conducted a 2-year field experiment (2020–2022) to investigate the effects of seasonal irrigation, potassium application and their interaction on cocoa reproduction and yield, using six genotypes in Côte d’Ivoire. Potassium application increased pod number and size, contributing significantly to annual yield, but this effect was conditional to soil water availability. Similarly, irrigation when combined with potassium application almost doubled yield from 1.5 to 3.0 kg/tree (2000 kg ha−1 yr−1 to 4000 kg ha−1 yr−1, respectively). This yield effect was mostly the result of positive effects of irrigation on pod number per tree and, to a lesser extent, due to its positive effects on bean number per pod and bean mass. Irrigation effects on pod number were associated with an increased number of cherelles whereas the larger pod number during the major harvest compared to the minor harvest was associated with lower cherelle wilt. We also found a more than two-fold genotypic difference in yield, with the genotypes CI02 and CI03 and to a lesser extent hybrid M having lower yields having lower yields than the genotype CI01. These genotypic yield differences were associated with differences in both cherelle wilt and initial cherelle production rates. The effects of withholding irrigation on yield were significantly dependent on the genotype, reflecting a potential genotypic difference in drought tolerance. The development of climate adaptive strategies for cocoa production requires integrating effects of irrigation, potassium application and cocoa genotype on yields. Future research should focus on unraveling the underlying genotypic and ecophysiological mechanisms of the results presented here, and identifying other potential approaches to enhance the resilience of cocoa to increasing water deficit under climate change.
Molecular Surveillance, Prevalence, and Distribution of Cacao Infecting Badnavirus Species in Côte d’Ivoire and Ghana
The cacao swollen shoot disease (CSSD) caused by a complex of badnavirus species presents a major challenge for cacao production in West Africa, especially Ghana and Côte d’Ivoire. In this study, CSSD species detection efficiency, diversity, and geographic distribution patterns in cacao plantations in Ghana and Côte d’Ivoire were investigated through field surveillance, PCR detection assays, sequencing of positive amplicons, and phylogeographic clustering. Cumulatively, the detection efficiency of the tested CSSD primer sets that were targeting the movement protein domain of the virus ranged from 0.15% (CSSD-3 primer) to 66.91% (CSSD-1 primer) on all the symptomatic cacao leaf samples assessed. The identified CSSD species differed phylogenetically and overlapped in distribution, with the cacao swollen shoot Togo B virus (CSSTBV) (n = 588 sequences) being the most prevalent and widely distributed compared to the other CSSD species that were encountered in both countries. Geographically, the cacao swollen shoot CE virus (CSSCEV) species (n = 124 sequences) that was identified was largely restricted to the bordering regions of Ghana and Côte d’Ivoire. These results provide updated knowledge of the geographic distribution of the key CSSD species and their diagnostic efficiency and, thus, provide guidance in identifying locations for structured testing of cacao germplasm and optimal diagnostics for the predominant CSSD species in Ghana and Côte d’Ivoire.