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Cocoa beans are produced all across the humid tropics under different environmental conditions provided by the region but also by the season and the type of production system. Agroforestry systems compared to monocultures buffer climate extremes and therefore provide a less stressful environment for the understory cocoa, especially under seasonally varying conditions. We measured the element concentration as well as abiotic stress indicators (polyamines and total phenolic content) in beans derived from five different production systems comparing monocultures and agroforestry systems and from two harvesting seasons. Concentrations of N, Mg, S, Fe, Mn, Na, and Zn were higher in beans produced in agroforestry systems with high stem density and leaf area index. In the dry season, the N, Fe, and Cu concentration of the beans increased. The total phenolic content increased with proceeding of the dry season while other abiotic stress indicators like spermine decreased, implying an effect of the water availability on the chemical composition of the beans. Agroforestry systems did not buffer the variability of stress indicators over the seasons compared to monocultures. The effect of environmental growing conditions on bean chemical composition was not strong but can contribute to variations in cocoa bean quality.

The response of plant species to environmental conditions influences changes in functional traits associated with the process that determines biological fitness and ecosystem processes. However, documenting these responses remain largely elusive in cultivation systems. We analyzed how environmental variables and leaf traits have effects on the transpiration rate of cocoa (Theobroma cacao L.) trees compared among different cultivation systems. Fieldwork was carried out at the Sara Ana experimental station in Alto Beni, La Paz, Bolivia. We sampled four trees in each of eight plots; four plots for each cultivation system (organic monoculture vs. organic agroforestry). From each tree, two mature, sunlit and healthy leaves were collected to make measurements of foliar traits and environmental variables. We found that canopy cover was higher in the agroforestry system. The specific leaf area was greater in agroforestry but the stomata size was significantly higher in the monoculture system. Temperature had a positive relationship with transpiration, whereas canopy cover and specific leaf area had a negative relationship in the agroforestry system. Cultivation system caused changes in microenvironmental conditions and on the expression of leaf traits that regulate water flow through the plant. Thus, the mutual effects of canopy cover, larger leaves and smaller stomatal size may drive a more efficient water use by reducing the transpiration rate of plants growing in agroforestry systems.

Overaged full-sun cacao plantations and the need for sustainable production systems call for combining rehabilitation of plantations with the establishment of agroforestry. We tested the effect of drastic rehabilitation pruning of old cacao tree stock and the introduction of both high- and low-diversity agroforestry on survival, growth and yield of T. cacao in a commercial plantation in peninsular Malaysia over a period of 5 years. We further determined the incidence of pests and diseases of cacao pods and assessed the performance of the whole system for smallholder farmers, including yields of by-crops. Rehabilitation pruning negatively affected cacao tree development and short-term yield. No more effects of pruning on cacao yield were observed starting in the third year on in the monoculture and starting in the fourth year on in low-diversity agroforestry. We found similar cacao tree development and yield in the low-diversity agroforestry and a common practice monoculture, suggesting that the implementation of agroforestry is a commercially feasible strategy, due to additional income generated through timber production. Reduced cacao tree development and yield in the high-diversity agroforestry were compensated by additional harvests of cassava and banana compared to monoculture. Incidence of cocoa pod borer (Conopomorpha cramerella) was lower in the agroforestry systems, especially the high-diversity system, while the incidence of black pod disease (Phytophthora spp.) did not differ between agroforestry and monoculture. The findings highlight the potential of agroforestry to reconcile ecologically sustainable land use with natural, cost-effective pest management. While pruning needs to be done with timing and disease pressure in mind to minimize short-term yield losses, this measure proved to be a feasible strategy for establishing agroforestry on extant plantations.

Pests and diseases threaten cacao production worldwide. Agroforestry systems are traditionally seen by farmers as one of the causes of increased pest and disease incidence, in contrast with full-sun monocultures. Cultural management practices—e.g. regular tree pruning, frequent pod harvest, regular removal of infested pods, weed management—have been reported to be crucial for pest and disease management. We performed two experiments for the purpose of assessing the effect of (i) different cacao production systems, and (ii) the frequency of harvest and removal of infested pods on the incidence of pests and diseases and on the cacao yield. The first experiment was performed in a long-term system comparison trial in Bolivia, where data on pest and disease incidence were recorded for three years in five production systems: two monocultures and two agroforestry system under organic and conventional farming, and one successional agroforestry system, i.e. a high tree density multi-strata system. Pest and disease management did not differ between systems and relied on cultural management practices. Overall, the incidence of pests and diseases did not differ between production systems, which indicated they were not the driver of yield differences between them. Across production systems, only 14% of the pods were affected by pests and diseases; 70% of these were affected by frosty pod rot. More than 80% of the pods infected by frosty pod rot were removed before the sporulation phase. In the second experiment, the effects of the frequency of harvest and removal of infected pods—every 15 days versus every 25 days—on pest and disease incidence and yield were tested in four farmers’ fields. Fortnightly harvest and diseased pod removal significantly decreased disease incidence and increased cacao yield, by 25% and 46% respectively. Our results show that cacao agroforestry systems do not increase pest and disease incidence compared with monocultures when good cultural management practices are implemented, which, in turn, can increase the productivity of the cacao plantations.

Farmers expect yield reduction of cash crops like cocoa when growing in agroforestry systems compared to monocultures, due to competition for resources, e.g. nutrients and water. However, complementarities between species in the use of resources may improve resource use efficiency and result in higher system performance. Cocoa trees have a shallow rooting system while the rooting characteristics of the associated trees are mainly unknown. This work investigates fine root distribution and production in five cocoa production systems: two monocultures and two agroforestry systems under conventional and organic farming, and a successional agroforestry system. In the organic systems a perennial leguminous cover crop was planted and compost was added, while herbicides and chemical fertilizers were applied in the conventional ones. We measured cocoa fine root parameters in the top 10 cm of soil and annual total fine root production at 0–25 and 25–50 cm depth. We related the root data with both the aboveground performance (tree and herbaceous biomass), and the cocoa and system yields. Cocoa fine roots were homogenously distributed over the plot area. Around 80% of the total fine roots were located in the upper 25 cm of soil. The total fine root production was 4-times higher in the agroforestry systems and the organic monoculture than in the conventional monoculture. The roots of the associated tree species were located in the same soil space as the cocoa roots and, in principle, competed for the same soil resources. The cocoa yield was lower in the agroforestry systems, but the additional crops generated a higher system yield and aboveground biomass than the conventional cocoa monocultures, implying effective resource exploitation. The leguminous cover crop in the organic monoculture competed with the cocoa trees for nutrients, which may explain the lower cocoa yield in this system in contrast with the conventional monoculture.

SUMMARYAgroforestry systems (AFS) can serve to decrease ecosystem carbon (C) losses caused by deforestation and inadequate soil management. Because of their shade tolerance, cacao plants are suitable to be grown in AFS, since they can be combined with other kinds of trees and shrubs. The potential for C sequestration in cacao farming systems depends on various factors, such as management practices, stand structure and plantation age. We compared conventionally and organically managed cacao monoculture systems (MCS) and AFS in Sara Ana (Bolivia) with respect to C stocks in plant biomass and to amounts of litterfall and pruning residues. The total aboveground C stocks of the AFS (26 Mg C ha−1) considerably exceeded those of the MCS (~7 Mg C ha−1), although the biomass of cacao trees was greater in the MCS compared to the AFS. Due to higher tree density, annual litterfall in the AFS (2.2 Mg C ha−1 year−1) substantially exceeded that in the MCS (1.2 Mg C ha−1 year−1). The amounts of C in pruning residues (2.6 Mg C ha−1 year−1 in MCS to 4.3 Mg C ha−1 year−1 in AFS) was more than twice those in the litterfall. Annual nitrogen (N) inputs to the soil through pruning residues of cacao and N-fixing trees were up to 10 times higher than the N inputs through external fertiliser application. We conclude that appropriate management of cacao AFS, involving the pruning of leguminous trees, will lead to increases in biomass, litter quantity and quality as well as soil C and N stocks. Thus, we recommend stimulating the expansion of well-managed AFS to improve soil fertility and enhance C sequestration in soils.

International audience; AbstractKey messageShade trees in agroforestry systems protect the understory cocoa from climate extremes. Shade tree pruning manages microclimatic conditions in favor of cocoa production while tree diversity is maintained. Adaptation of pruning has to consider seasonal changes in temperature and precipitation to protect the understory cocoa.ContextStructural characteristics of tree stands such as species diversity, tree density, and stratification can affect throughfall and microclimate. Pruning changes the canopy and may therefore modulate internal conditions.AimsThe aim of this study is to assess the environmental growing conditions of cocoa trees.MethodsWe monitored canopy openness and the impact of stand structure on throughfall and microclimate in three cocoa production systems (monoculture, agroforestry, and successional agroforestry) and a natural regrowth in a long-term trial in Bolivia from 2013 to 2015. We further focused on the effect of annual shade tree and cocoa pruning on these variables to evaluate the potential impact of this activity.ResultsAgroforestry systems buffered extreme climate events like temperature fluctuations compared to monocultures but reduced light and throughfall drastically. Spatial variability of throughfall and transmitted light were low under a high and closed shade tree canopy. Shade tree pruning resulted in higher canopy openness, light transmittance, and throughfall, while the buffer function of the agroforestry systems concerning temperature and humidity fluctuations was reduced.ConclusionDifferences between cocoa production systems regarding throughfall and microclimate were overlain by pruning activities. Cocoa agroforestry systems are temporal dynamic systems. Pruning timing and intensity is pivotal for balancing light and water availability under seasonally varying environmental conditions to conserve micro-environments for cocoa production with less exposure to unfavorable climate.

The global demand for cacao has recently increased. To meet this demand, the cultivated area has been expanded in tropical forest areas and production has intensified by replacing traditional agroforestry systems with monocultures. This has led to a loss of biodiversity in cacao-growing areas. More sustainable production systems such as agroforestry and organic managed systems are expected to yield less cacao, but by-crops and premium prices, respectively, might economically compensate for the lower yields. Here, we compared the productivity and the return on labor, that is the return per working day, of four different cacao production systems: agroforestry and monocultures under organic and conventional management. Cacao and by-crop yields, costs, revenues, and labor were registered during the first 5 years after establishment. Results show that cacao yields were, on average, 41% higher in monocultures, but the revenues derived from agroforestry by-crops economically overcompensated for this difference. Indeed, the return on labor across the years was roughly twice as high in the agroforestry systems compared to the monocultures. We found similar cacao yields and return on labor in conventional and organically managed agroforestry systems. However, in the monocultures, cacao yields were 48% lower under organic compared with conventional farming, but the return on labor was similar, mainly due to the higher costs associated to the conventional management. Overall, our findings show that cacao agroforestry systems have higher return on labor.

Cadmium (Cd) uptake by cocoa has recently attracted attention, after the European Union (EU) decided to establish values for tolerable Cd concentrations in cocoa products. Bean Cd concentrations from some cocoa provenances, especially from Latin America, were found to exceed these values. Cadmium uptake by cocoa is expected not only to depend on a variety of soil factors, but also on plant and management factors. In this study, we investigated the influence of different production systems on Cd uptake by cocoa in a long-term field trial in the Alto Beni Region of Bolivia, where cocoa trees are grown in monocultures and in agroforestry systems, both under organic and conventional management. Leaf, fruits and roots of two cultivars were sampled from each production system along with soil samples collected around these trees. Leaf, pod husk and bean samples were analysed for Cd, iron (Fe) and zinc (Zn), the roots for mycorrhizal abundance and the soil samples for 'total' and 'available' Cd, Fe and Zn as well as DGT-available Cd and Zn, pH, organic matter, texture, 'available' phosphorus (P) and potassium (K). Only a small part of the variance in bean and pod husk Cd was explained by management, soil and plant factors. Furthermore, the production systems and cultivars alone had no significant influence on leaf Cd. However, we found lower Cd leaf contents in agroforestry systems than in monocultures when analysed in combination with DGT-available soil Cd, cocoa cultivar and soil organic matter. Overall, this model explained 60% of the variance of the leaf Cd concentrations. We explain lower leaf Cd concentrations in agroforestry systems by competition for Cd uptake with other plants. The cultivar effect may be explained by cultivar specific uptake capacities or by a growth effect translating into different uptake rates, as the cultivars were of different size.

The growing demand for cocoa beans and products worldwide has been met by expanding the area under cocoa production while productivity per hectare has stagnated at a low level of around 450 kg/ha per year in the last decade. Throughout the tropics cocoa has increasingly been cultivated in full-sun monocultures in order to maximize short-term productivity and profitability, which has been associated with soil erosion and degradation, biodiversity loss, as well as increased susceptibility to climate change impacts and pests and diseases. Dynamic agroforestry systems are an alternative production method which has long been practiced in Latin American countries such as Bolivia. Through mimicking natural forests, these systems offer multiple benefits such as soil fertility enhancement, reduction in pest and disease pressure, erosion control, and revenue diversification. In Côte d’Ivoire, where most cocoa is still produced in monocultures, dynamic agroforestry systems were recently introduced on a small scale. Here we use different research projects conducted in Bolivia and Côte d’Ivoire as case studies to review productivity, soil fertility as well as pests and diseases in dynamic agroforestry systems and monocultures, and outline factors influencing the adoption of dynamic agroforestry systems from the farmers’ perspective. We found productivity under agroforestry systems to be either similar or higher compared to monocultures. We recorded 161 % higher total system yields in an on-station field trial and an on-farm study in Bolivia, and in an on-farm study in Côte d’Ivoire. Cocoa yields were 12–46 % higher in agroforestry systems compared to monocultures. In addition, cocoa in dynamic agroforestry systems exhibited significantly less incidences of witches’ broom, Moniliophthora perniciosa, compared to monocultures in Bolivia. Farmers in Bolivia and Côte d’Ivoire observed more soil-related problems and incidences of pests and diseases in monocultures than in agroforestry systems, and they showed high interest to learn dynamic agroforestry management practices. However, adoption was strongly limited to project areas where dynamic agroforestry plots had been installed with farmers’ participation. This highlights the importance of local organizations such as Ecotop, Ecosaf, El Ceibo and Biopartenaire Ltd., who implement such interventions on the ground. However, we found that there is space for improvement in the way organizations interact with farmers, especially in Côte d’Ivoire. Interactive knowledge sharing methods such as farmer field schools may help to stimulate farmers’ protagonism and give scientists and external consultants the role of facilitators who integrate different forms of knowledge and make them visible to different stakeholders. Such a social learning process requires transdisciplinary research for the development of decision support tools which facilitate the determination of both optimal planting densities and shade levels, as well as adequate combinations of trees and accompanying species in order to achieve effective regulation of pests and diseases while ensuring favourable growing conditions.

Cocoa is one of the most important crops of the ‘‘Alto Beni’’ region in Bolivia. This crop is produced in different systems, among them monoculture and agroforestry. In order to determine the effect of the production system on microbiological soil characteristics, we measured microbial biomass carbon, microbial biomass nitrogen and cellulase activity and we determined the microbial quotient in soil under five different cocoa production systems (conventional monoculture, organic monoculture, conventional agroforestry, organic agroforestry and successional agroforestry) and in fallow plots. The measurements were carried out in dry and rainy season. Soil from fallow plots and soil under agroforestry had higher microbial biomass than soils under monocultures, probably due to the effect of fresh organic matter input on microbial biomass. No significant difference for microbial biomass in soil from plots subjected to organic management and soil from plots subjected to conventional management was observed, possibly because of the short time elapsed from the initial establishment of the plots. In dry season, the microbial quotient showed a significantly higher value in soils under conventional agroforestry than in soils under organic monoculture, suggesting that besides the input of fresh organic matter, mineral fertilization may play a role on the fraction of available carbon. Cellulase activity was not affected by any of the factors tested, indicating that, under our assay conditions, it was not a good indicator of changes in soil.

This study compares aboveground and belowground carbon stocks and tree diversity in different cocoa cultivation systems in Bolivia: monoculture, simple agroforestry, and successional agroforestry, as well as fallow as a control. Since diversified, agroforestry-based cultivation systems are often considered important for sustainable development, we also evaluated the links between carbon stocks and tree diversity, as well as the role of organic certification in transitioning from monoculture to agroforestry. Biomass, tree diversity, and soil physiochemical parameters were sampled in 15 plots measuring 48 × 48 m. Semi-structured interviews with 52 cocoa farmers were used to evaluate the role of organic certification and farmers’ organizations (e.g., cocoa cooperatives) in promoting tree diversity. Total carbon stocks in simple agroforestry systems (128.4 ± 20 Mg ha−1) were similar to those on fallow plots (125.2 ± 10 Mg ha−1). Successional agroforestry systems had the highest carbon stocks (143.7 ± 5.3 Mg ha−1). Monocultures stored significantly less carbon than all other systems (86.3 ± 4.0 Mg ha−1, posterior probability P(Diff > 0) of 0.000–0.006). Among shade tree species, Schizolobium amazonicum, Centrolobium ochroxylum, and Anadenanthera sp. accumulated the most biomass. High-value timber species (S. amazonicum, C. ochroxylum, Amburana cearensis, and Swietenia macrophylla) accounted for 22.0 % of shade tree biomass. The Shannon index and tree species richness were highest in successional agroforestry systems. Cocoa plots on certified organic farms displayed significantly higher tree species richness than plots on non-certified farms. Thus, expanding the coverage of organic farmers’ organizations may be an effective strategy for fostering transitions from monoculture to agroforestry systems.

Cocoa-based small-scale agriculture is the most important source of income for most farming families in the region of Alto Beni in the sub-humid foothills of the Andes. Cocoa is grown in cultivation systems of varying ecological complexity. The plantations are highly susceptible to climate change impacts. Local cocoa producers mention heat waves, droughts, floods and plant diseases as the main impacts affecting plants and working conditions, and they associate these impacts with global climate change. From a sustainable regional development point of view, cocoa farms need to become more resilient in order to cope with the climate change related effects that are putting cocoa-based livelihoods at risk. This study assesses agroecosystem resilience under three different cocoa cultivation systems (successional agroforestry, simple agroforestry and common practice monocultures). In a first step, farmers’ perceptions of climate change impacts were assessed and eight indicators of agroecological resilience were derived in a transdisciplinary process (focus groups and workshop) based on farmers’ and scientists’ knowledge. These indicators (soil organic matter, depth of Ah horizon, soil bulk density, tree species diversity, crop varieties diversity, ant species diversity, cocoa yields and infestation of cocoa trees with Moniliophthora perniciosa) were then surveyed on 15 cocoa farms and compared for the three different cultivation systems. Parts of the socio-economic aspects of resilience were covered by evaluating the role of cocoa cooperatives and organic certification in transitioning to more resilient cocoa farms (interviews with 15 cocoa farmers combined with five expert interviews). Agroecosystem resilience was higher under the two agroforestry systems than under common practice monoculture, especially under successional agroforestry. Both agroforestry systems achieved higher cocoa yields than common practice monoculture due to agroforestry farmers’ enhanced knowledge regarding cocoa cultivation. Knowledge sharing was promoted by local organizations facilitating organic certification. These organizations were thus found to enhance the social process of farmers’ integration into cooperatives and their reorientation toward organic principles and diversified agroforestry.