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Increasing demand for cocoa and climate-related yield declines have sparked a multi-stakeholder debate on cocoa production strategies. Agrochemical inputs and pollination enhancement through hand pollination are two strategies to increase yields. Here, we test both strategies with field experiments in Indonesia. We show that even partial hand pollination (13% of easily accessible flowers/tree), and not fertilizers or insecticides, increases yield/tree by 51%. The more laborious 100% hand pollination of the entire tree increases yield/tree by 161%, and farmer's annual net income from 994 USD/ha up to 1,677 USD/ha, or 69% in the study area, after accounting for farm operational, hand pollination labor, and opportunity costs. Thus, intensifying cocoa pollination appears to be a potential solution for closing cocoa yield gaps and should be considered in the current industry-led discussion of designing farms for mitigation of climate change.
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... Because low pollen deposition can be linked to suboptimal cacao fruit set (Falque et al., 1996;Mena-Montoya et al., 2020), it is important to better understand the link between pollen deposition rates in the field and actual fruit setting rates. Limiting effects of pollen quantity and compatibility on yield can be alleviated by hand pollination (Toledo-Hernández et al., 2020), particularly so in self-incompatible cacao varieties . Manual pollen supplementation has been found to triple yields and increase cacao farmers' incomes by up to 69% (Toledo-Hernández et al., 2020). ...
... Limiting effects of pollen quantity and compatibility on yield can be alleviated by hand pollination (Toledo-Hernández et al., 2020), particularly so in self-incompatible cacao varieties . Manual pollen supplementation has been found to triple yields and increase cacao farmers' incomes by up to 69% (Toledo-Hernández et al., 2020). However, yield gains through hand pollination depend on environmental factors, cross-compatibility levels and timing (de Almeida & Valle, 2009;Forbes et al., 2019). ...
... Before starting the experiments, we visually confirmed that pollen deposition was over 100 grains with a microscope (Figure S3). Following similar study designs used in Asia, flowers were not isolated from flower visitors before or after hand pollination(Groeneveld et al., 2010;Toledo-Hernández et al., 2020).Six days after manual pollination, we counted the young fruits smaller than 1 cm (hereafter cherelles), as this size corresponds with ∼7 days old cherelles. Weekly fruit set rates were defined as cherellesobserved 6 days after pollination, divided by the number of open flowers recorded 6 days earlier. ...
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Pollination services of cacao are crucial for global chocolate production, yet remain critically understudied, particularly in regions of origin of the species. Notably, uncertainties remain concerning the identity of cacao pollinators, the influence of landscape (forest distance) and management (shade cover) on flower visitation and the role of pollen deposition in limiting fruit set. Here, we aimed to improve understanding of cacao pollination by studying limiting factors of fruit set in Peru, part of the centre of origin of cacao. Flower visitors were sampled with sticky insect glue in 20 cacao agroforests in two biogeographically distinct regions of Peru, across gradients of shade cover and forest distance. Further, we assessed pollen quantities and compared fruit set between naturally and manually pollinated flowers. The most abundant flower visitors were aphids, ants and thrips in the north and thrips, midges and parasitoid wasps in the south of Peru. We present some evidence of increasing visitation rates from medium to high shade (40%–95% canopy closure) in the dry north, and opposite patterns in the semi‐humid south, during the wet season. Natural pollination resulted in remarkably low fruit set rates (2%), and very low pollen deposition. After hand pollination, fruit set more than tripled (7%), but was still low. The diversity and high relative abundances of herbivore flower visitors limit our ability to draw conclusions on the functional role of different flower visitors. The remarkably low fruit set of naturally and even hand pollinated flowers indicates that other unaddressed factors limit cacao fruit production. Such factors could be, amongst others, a lack of effective pollinators, genetic incompatibility or resource limitation. Revealing efficient pollinator species and other causes of low fruit set rates is therefore key to establish location‐specific management strategies and develop high yielding native cacao agroforestry systems in regions of origin of cacao. Pollination services of cacao are crucial for global chocolate production, yet remain critically understudied, particularly in regions of origin of the species. Notably, uncertainties remain concerning the identity of cacao pollinators, the influence of landscape (forest distance) and management (shade cover) on flower visitation and the role of pollen deposition in limiting fruit set. Here, we aimed to improve understanding of cacao pollination by studying limiting factors of fruit set in Peru, part of the centre of origin of cacao. Flower visitors were sampled with sticky insect glue in 20 cacao agroforests in two biogeographically distinct regions of Peru, across gradients of shade cover and forest distance. Further, we assessed pollen quantities and compared fruit set between naturally and manually pollinated flowers. The most abundant flower visitors were aphids, ants and thrips in the north and thrips, midges and parasitoid wasps in the south of Peru. We present some evidence of increasing visitation rates from medium to high shade (40%–95% canopy closure) in the dry north, and opposite patterns in the semi‐humid south, during the wet season. Natural pollination resulted in remarkably low fruit set rates (2%), and very low pollen deposition. After hand pollination, fruit set more than tripled (7%), but was still low. The diversity and high relative abundances of herbivore flower visitors limit our ability to draw conclusions on the functional role of different flower visitors. The remarkably low fruit set of naturally and even hand pollinated flowers indicates that other unaddressed factors limit cacao fruit production. Such factors could be, amongst others, a lack of effective pollinators, genetic incompatibility or resource limitation. Revealing efficient pollinator species and other causes of low fruit set rates is therefore key to establish location‐specific management strategies and develop high yielding native cacao agroforestry systems in regions of origin of cacao. Los servicios de polinización del cacao son cruciales para la producción mundial de chocolate, pero están poco estudiados, especialmente en las regiones donde se originó la especie. En particular, sigue existiendo incertidumbre sobre la identidad de los polinizadores del cacao, la influencia del paisaje (distancia al bosque) y el manejo (cobertura de sombra) en la visita floral, y el papel que juega la deposición de polen en limitar el cuajado de los frutos. Este trabajo tuvo como objetivo mejorar el conocimiento sobre la polinización del cacao, mediante el estudio de los factores limitantes del cuajado en Perú, parte del centro de origen del cacao. Muestreamos los visitantes florales con pegamento para insectos en 20 sistemas agroforestales de cacao en dos regiones biogeográficamente distintas del Perú, a lo largo de gradientes de cobertura de sombra y distancia al bosque. Además, evaluamos la cantidad de polen y comparamos la fructificación entre flores polinizadas natural y manualmente. Los visitantes florales más abundantes en el norte de Perú fueron áfidos, hormigas y trips; en el sur fueron trips, mosquitos y avispas parasitoides. Presentamos evidencia de un aumento en las tasas de visita con condiciones de sombra media o alta (40 ‐ 95% del dosel cerrado) en el norte seco, y patrones opuestos en el sur semi‐húmedo, durante la estación húmeda. La polinización natural resultó en tasas de cuajado de frutos notablemente bajas (2%), y en una deposición de polen muy baja. Con polinización manual, la fructificación se triplicó (7%), pero siguió siendo baja. La diversidad y la alta abundancia relativa de visitantes florales herbívoros, limitaron arrojar conclusiones sobre el papel funcional de distintos visitantes florales. La notablemente baja fructificación de las flores polinizadas naturalmente e incluso manualmente, indica que otros factores no abordados limitan la producción frutal del cacao. Estos factores podrían ser, entre otros, la falta de polinizadores eficientes, incompatibilidad genética o limitación de recursos. Por lo tanto, identificar las especies de polinizadores efectivos, así como causas adicionales de las bajas tasas de cuajado de los frutos son clave para poder establecer estrategias de manejo local, así como para desarrollar sistemas agroforestales de cacao nativo de alto rendimiento en las regiones de origen del cacao. Los servicios de polinización del cacao son cruciales para la producción mundial de chocolate, pero están poco estudiados, especialmente en las regiones donde se originó la especie. En particular, sigue existiendo incertidumbre sobre la identidad de los polinizadores del cacao, la influencia del paisaje (distancia al bosque) y el manejo (cobertura de sombra) en la visita floral, y el papel que juega la deposición de polen en limitar el cuajado de los frutos. Este trabajo tuvo como objetivo mejorar el conocimiento sobre la polinización del cacao, mediante el estudio de los factores limitantes del cuajado en Perú, parte del centro de origen del cacao. Muestreamos los visitantes florales con pegamento para insectos en 20 sistemas agroforestales de cacao en dos regiones biogeográficamente distintas del Perú, a lo largo de gradientes de cobertura de sombra y distancia al bosque. Además, evaluamos la cantidad de polen y comparamos la fructificación entre flores polinizadas natural y manualmente. Los visitantes florales más abundantes en el norte de Perú fueron áfidos, hormigas y trips; en el sur fueron trips, mosquitos y avispas parasitoides. Presentamos evidencia de un aumento en las tasas de visita con condiciones de sombra media o alta (40 ‐ 95% del dosel cerrado) en el norte seco, y patrones opuestos en el sur semi‐húmedo, durante la estación húmeda. La polinización natural resultó en tasas de cuajado de frutos notablemente bajas (2%), y en una deposición de polen muy baja. Con polinización manual, la fructificación se triplicó (7%), pero siguió siendo baja. La diversidad y la alta abundancia relativa de visitantes florales herbívoros, limitaron arrojar conclusiones sobre el papel funcional de distintos visitantes florales. La notablemente baja fructificación de las flores polinizadas naturalmente e incluso manualmente, indica que otros factores no abordados limitan la producción frutal del cacao. Estos factores podrían ser, entre otros, la falta de polinizadores eficientes, incompatibilidad genética o limitación de recursos. Por lo tanto, identificar las especies de polinizadores efectivos, así como causas adicionales de las bajas tasas de cuajado de los frutos son clave para poder establecer estrategias de manejo local, así como para desarrollar sistemas agroforestales de cacao nativo de alto rendimiento en las regiones de origen del cacao. Pollination of native cacao is surprisingly understudied, even though the process is crucial for the global chocolate production. In an understudied peruvian region, we found herbivores as dominant flower visitors, and low pollen deposition.Fruit set was low when flowers were pollinated naturally (2%), but also manually (7%). Our findings highlight the need to identify cacao pollinators that deposit sufficient compatible pollen, as well as more research on the origin of low fruit set in native cacao.
... Nowadays, pollination limitation has been documented in many crops (Holland et al., 2020;Reilly et al., 2020). Examples include the production of macadamia in South Africa (Grass et al., 2018), shea in West Africa (Delaney et al., 2020), cacao in Indonesia (Toledo-Hern andez et al., 2020), apple in Europe (Osterman, Theodorou, Radzevi ciut_ e, Schnitker, & Paxton, 2021), custard apple in Australia (Pritchard & Edwards, 2006) and eggplant in India (Bhattacharya & Basu, 2018). Here, pollination limitation was related to the limited pollination efficiency of honey bees (Apis mellifera, Apis cerana) and the decline of wild bees or non-bee pollinators due to habitat simplification or loss. ...
... For tomatoes in Australia, 60 h are needed to hand pollinate one hectare of crops with an electric vibrating wand or electric bee (Bell et al., 2006). For cacao, one worker needs around seven minutes to pollinate one complete tree (Toledo-Hern andez et al., 2020). Thus 77 cacao trees can be fully pollinated in an 8À9 h working day, resulting in hand pollination costs of 1170 USD/ha (Toledo-Hern andez et al., 2020). ...
... For cacao, one worker needs around seven minutes to pollinate one complete tree (Toledo-Hern andez et al., 2020). Thus 77 cacao trees can be fully pollinated in an 8À9 h working day, resulting in hand pollination costs of 1170 USD/ha (Toledo-Hern andez et al., 2020). For the Dutch tomato production, costs of US$ 18million were estimated for the hand pollination of 1600 ha (Van Heemert et al., 1990). ...
Article
Global pollinator declines and land-use change can lead to pollination limitation with implications for agricultural productivity. Hand pollination is used in agricultural production as a technique to manually pollinate crops. But the prevalence of hand pollination, as well as benefits and costs, remain unknown. We systematically reviewed the literature for examples, methods, drivers, and economic motivations of hand pollination. Furthermore, we discuss the risks, constraints, and opportunities of hand pollination. We found evidence for 20 hand-pollinated crops, including minor but also economically important crops (e.g. apple, oil palm, cacao). The lack of pollinators was the most important reason for the application of hand pollination (50% of crops), while insufficient proportion or proximity of pollinizers (8% of crops) and skewed sex ratio or dichogamy (8% of crops) were second most important. The main economic motivations for practicing or recommending hand pollination were to increase fruit set, and/or fruit quality (78% of crops). Hand pollination is practiced in large- and small-scale farming, home gardens, and greenhouses. Opportunities of hand pollination are the control of pollen origin and quantity, pollination timing and frequency as well as independence from environmental fluctuations. Farmers can increase yields, improve fruit quality, avoid fruit abortion, increase employment, and secure subsistence food. The main constraints of hand pollination are high labor inputs, high material costs, and required skills. Major risks of hand pollination include management ignoring pollinator conservation, high food prices, over-pollination, labor accidents, and unfair labor. We conclude that in the face of global change, hand pollination allows improved control of pollination and is likely to increase in importance. The benefits of hand pollination need to outweigh the costs and fair labor is essential. Altogether, hand pollination can be a valuable tool for crop systems where pollinators are absent or are not reliable for sustaining high-quality crop production.
... Pollination of cocoa is largely dependent on midges whose growth, development and survival depend on how moist or humid the farm is. Artificial pollination has been found associated with natural pollination (Forbes et al. 2019;Toledo-Hernández et al. 2020;Vera-Chang et al. 2016). Artificial pollination happens when there is a human intervention in the pollination process. ...
... They found that natural pollination had the least number of flowers pollinated as well as the lowest fruit weight. Toledo-Hernández et al. (2020) found that a partial hand pollination of just 13% of easily accessible flowers or trees without fertilizers or insecticides resulted in 51% increase in yield of cocoa. A 100% hand pollination of the entire tree increased the yield by 161% as well as led to an increase of net income from $994/ha to $1,677/ha. ...
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This study examined the perception and adoption of artificial pollination among cocoa farmers in Ghana. It used cross-sectional data collected from 206 cocoa farmers selected through multi-stage sampling technique. Descriptive statistics, Likert Scale and the Tobit regression model were the methods of analysis. With an adoption rate of 49%, the study revealed that cocoa farmers have a positive perception towards adoption of artificial pollination technology. The results also showed that age of farmer, extension visits, yield and household size have significant positive effects on the probability of adoption of artificial pollination among cocoa farmers, whereas farm size has a significant negative effect on adoption. Leveraging on the positive perception generated, we encourage extension agents to sensitize farmers on the importance of artificial pollination through continuous awareness creation and promotion of the benefits of adopting the technology. Furthermore, given cocoa farmers’ positive perception on artificial pollination, Ghana’s cocoa production and marketing regulatory body (COCOBOD) should take steps in implementing the technology. Implementers of this technology should also target younger farmers since age has a negative influence on adoption of artificial pollination. Finally, this paper contributes to the literature by focusing on the perception and the factors that influence adoption of artificial pollination in cocoa production which currently has not been researched and documented in the cocoa production literature.
... Artificial pollination is the best solution to the problems associated with natural pollination [18][19][20]. Artificial pollination is said to have taken place when human intervention is involved in the pollination process. It is therefore a mechanical process facilitated by human beings to pollinate plants. ...
... It was found that amongst all the methods of pollination studied, natural pollination had the lowest number of flowers that were pollinated and also the least fruit weight, making artificial pollination, no matter the method used, more superior and rewarding. Ref. [20] found that about 13% of easily accessible trees and flowers that were partially hand-pollinated without application of fertilizer or insecticides led to an increase in the yield of cocoa of about 51% in Indonesia. Total pollination of the entire tree also led to a 161% increase in yield and net income. ...
Article
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This study analyzed the impact of the adoption of artificial pollination on productivity, income, poverty, and food security among cocoa farmers in Ghana. Primary data was collected from 206 cocoa farmers, drawn through a multi-stage sampling technique and analyzed using Propensity Score Matching. The study revealed that households who adopted artificial pollination had improvement in their productivity, income, poverty, and food security. It was also revealed that adopters increased their productivity by close to 15.34% on average, earns between GHC 2756.84 to GHC 11074.38 more on average in terms of income, reduced their poverty by an average of between 0.83% and 3.53%, and improved the food security by approximately 3% compared to non-adopters. Leveraging on the positive impact of the adoption of artificial pollination, policymakers should take steps in implementing artificial pollination to increase the yield of cocoa.
... However, higher labour requirements can improve agronomic outcomes without technical interventions in some farming systems. Hand pollination, and not pesticides or inorganic fertilizers, was found to increase cocoa yields by up to 161% and farmer income by 69% in Indonesia, indicating providing habitat for pollinators can be more effective at increasing yields than applying agrochemicals (Toledo-Hernández et al. 2020). In LMICs, new demand for labour under agroecology opens up rural employment opportunities. ...
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Governments are updating national strategies to meet global goals on biodiversity, climate change and food systems proposed in the Convention on Biological Diversity post-2020 framework and agreed at the United Nation’s Climate Change Conference (COP26) and Food Systems Summit (UNFSS). This represents a unique and crucial opportunity to integrate and accelerate food system actions to tackle interconnected global challenges. In this context, agroecology is a game-changing approach that can provide the world’s growing population with nutritious, healthy affordable food, ensure fair incomes to farmers and halt and reverse the degradation of the natural environment. Here, we explore agroecological transition pathways in four case studies from low- and middle- income countries and identify catalysts for change. We find that enabling policy and market environments, participatory action research and local socio-technical support each plays a critical role in stimulating transitions towards agroecology. We propose strategies and priorities for research to better support agroecological transitions using these catalysts of change as entry points. Engagement of governments, private sector, civil society, farmers and farm workers in this research agenda is essential.
... Increasing yield per unit area is one of the main challenges in cacao cultivation. Some studies have focused on manual pollinations, flowering and pollination intensities, and the plant nutritional status (Mustiga et al., 2018;Toledo-Hernández et al., 2020). Forbes et al. (2019) concluded that strategies to enhance flowering, pollination, and synchrony while ensuring adequate tree nutrition could increase cacao productivity. ...
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Sexual self-incompatibility is a very salient trait of woody plants, including cacao (Theobroma cacao L.). In this species, most commercial clones are self-incompatible and, therefore, productivity depends on pollen flow for fruit formation due to the combinatorial ability of each clone to accept or reject pollen tubes in the embryo sac. To determine the combinatorial ability of commercial cacao clones, artificial (manual) pollinations were performed between cacao clones of the same and between groups for three years. In total, 46 cacao clones of five geographical groups were evaluated: ‘FHIA’ from Honduras, ‘ICS’ from Trinidad and Tobago, ‘UF’ from Costa Rica, ‘CAUCASIA’ from Colombia, and ‘EET’ from Ecuador. The results showed that, except for ‘CAUCASIA’, there is a high level of inter-compatibility between groups. Cacao clones exceed the established threshold of 30% in Fruit Set Success when used as a female or a male donor. As expected, low self-compatibility rates were found among the clones studied. We propose the use of sexual inter-compatibility information for the design of planting arrangements to maximize cacao yields.
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Premise of the study: The role of pollen flow within and between cultivated and wild tropical crop species is little known. To study the pollen flow of cacao, we estimated the degree of self-pollination and pollen dispersal distances as well as gene flow between wild and cultivated cacao (Theobroma cacao L.). Methods: We studied pollen flow and genetic diversity of cultivated and wild cacao populations by genotyping 143 wild and 86 cultivated mature plants and 374 seedlings raised from 19 wild and 25 cultivated trees at nine microsatellite loci. Key results: A principal component analysis distinguished wild and cultivated cacao trees, supporting the notion that Bolivia harbors truly wild cacao populations. Cultivated cacao had a higher level of genetic diversity than wild cacao, presumably reflecting the varied origin of cultivated plants. Both cacao types had high outcrossing rates, but the paternity analysis revealed 7-14% self-pollination in wild and cultivated cacao. Despite the tiny size of the pollinators, pollen was transported distances up to 3 km; wild cacao showed longer distances (mean = 922 m) than cultivated cacao (826 m). Our data revealed that 16-20% of pollination events occurred between cultivated and wild populations. Conclusions: We found evidence of self-pollination in both wild and cultivated cacao. Pollination distances are larger than those typically reported in tropical understory tree species. The relatively high pollen exchange from cultivated to wild cacao compromises genetic identity of wild populations, calling for the protection of extensive natural forest tracts to protect wild cacao in Bolivia.
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Tropical rainforests disappear at an alarming rate causing unprecedented losses in biodiversity and ecosystem services (Hughes et al. 1997, Noble & Dirzo 1997, Tilman et al. 2001, Achard et al. 2002) with Southeast Asia showing the highest rates of deforestation of any major tropical region (Sodhi et al. 2004). Despite an increased recognition of the value of these goods at national and international levels, rainforests continue to be seriously threatened by various forms of encroachments such as low-intensity harvesting of non-timber forest products by the rural poor, large-scale plantation forestry by the state or private actors, and the conversion of forested land by smallholder farmers. Transformation of ecosystems and changes in land use affect important ecosystem services and ultimatively human well-being (Robertson & Swinton 2005).
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Nutrient input–output balances are often used as indicators for the sustainability of land use systems. In a case study on plot scale in Central Sulawesi, Indonesia, we measured nutrient input–output balances of natural rainforest and two unfertilized land use systems (maize, and coffee/cacao agroforestry). These are the two major land use systems on converted rainforest sites in this part of Sulawesi. We wanted to test if (a) plant nutrient balances are negative, (b) which pathway is most important for losses of plant nutrients, and (c) if partial plant nutrient balances are suitable to evaluate sustainability of the land use systems. We measured nutrient inputs by precipitation and nutrient outputs by harvest export and leaching. We selected two locations, the first was situated on a fertile Cambisol developed on alluvial sediment soil, and the second on a less fertile Cambisol developed on weathered phyllite substrate. Nutrient losses through leaching were higher on sites with higher soil fertility. Nutrient balances in natural forest on fertile soils were negative for N, Ca, K and Mg. Inputs of P by precipitation and outputs by leaching were below detection limit. On less fertile soils, leaching of N and K in natural forest was lower than inputs by precipitation. As net nutrient losses were highest in agroforestry, followed by maize and natural forest stands, forest conversion into agricultural land will result in increased nutrient losses. Main output pathway of N, P and K was harvest, whereas main output pathway for Ca and Mg was through leaching. The annual losses of nutrients we measured were higher than in comparable studies on nutrient poor soils; however losses were only small fractions of available nutrient stocks. Our results showed negative partial nutrient balances in both agricultural systems. Nutrient balances in this study were more influenced by native soil fertility than by land use. Because we found indirect evidence that some nutrient pathways, which were not measured, may have significantly changed the overall balance (biological N fixation, weathering), we conclude that partial nutrient balances are no good indicators for sustainability of land use systems.
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Human activity endangers tropical forests in different parts of the world. The conflicting interests of nature conservation on the one hand, and the livelihood of farmers living at the forest margins, on the other, clash noticeably in so-called hotspots of biodiversity, such as the Lore Lindu region of Central Sulawesi, Indonesia. Biodiversity generally decreases along a land use gradient from natural forest to agroforestry and annual crop systems. Thus, before solutions for a sustainable balance between conservation and the needs of people living at the forest margins can be sought, changing land use strategies and the factors that influence them must be analyzed. While similar studies often concentrate on economic indicators of land use change only, this chapter highlights the importance of two cultural realities, namely migration and ethnicity. We will demonstrate the great influence of these two factors on land use decisions and on the accessibility of land in the Lore Lindu region.
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We studied the functional relationship between pollination intensity and fruit survival as well as the number of seeds per pod in the tropical tree Theobroma cacao L. on a Forastero Upper-Amazon clone (UPA 409) in Ivory Coast. Cutting the style 24 h after pollination allowed for counting the number of pollen grains deposited on a stigma without affecting fruit set and seed development. Forty-three pollen grains were necessary to reach 50% of maximum fruit set 28 days after pollination. Above 115 pollen grains, the proportion of developing ovaries reached a maximum of 88% 28 days after pollination and 75% at maturity. With fewer than 238 pollen grains per stigma, there was a close relationship between pollination intensity and number of seeds per pod; the pollenseed ratio increased from 1.61 to 3.81 for PI increasing from 30 to 238 pollen grains. For higher pollination intensities, the average number of seeds per pod reached a maximum of 58. The relationship between pollination intensity and seed content was modelled. Results are consistent with the hypothesis that ovules attracted pollen tubes in a similar way regardless of whether or not they had already been reached by another pollen tube.
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How should ecologists and evolutionary biologists analyze nonnormal data that involve random effects? Nonnormal data such as counts or proportions often defy classical statistical procedures. Generalized linear mixed models (GLMMs) provide a more flexible approach for analyzing nonnormal data when random effects are present. The explosion of research on GLMMs in the last decade has generated considerable uncertainty for practitioners in ecology and evolution. Despite the availability of accurate techniques for estimating GLMM parameters in simple cases, complex GLMMs are challenging to fit and statistical inference such as hypothesis testing remains difficult. We review the use (and misuse) of GLMMs in ecology and evolution, discuss estimation and inference and summarize 'best-practice' data analysis procedures for scientists facing this challenge.
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Local and landscape-scale agricultural intensification is a major driver of global biodiversity loss. Controversially discussed solutions include wildlife-friendly farming or combining high-intensity farming with land-sparing for nature. Here, we integrate biodiversity and crop productivity data for smallholder cacao in Indonesia to exemplify for tropical agroforests that there is little relationship between yield and biodiversity under current management, opening substantial opportunities for wildlife-friendly management. Species richness of trees, fungi, invertebrates, and vertebrates did not decrease with yield. Moderate shade, adequate labor, and input level can be combined with a complex habitat structure to provide high biodiversity as well as high yields. Although livelihood impacts are held up as a major obstacle for wildlife-friendly farming in the tropics, our results suggest that in some situations, agroforests can be designed to optimize both biodiversity and crop production benefits without adding pressure to convert natural habitat to farmland.
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The Guinean rain forest (GRF) of West Africa, identified over 20 years ago as a global biodiversity hotspot, had reduced to 113,000 km² at the start of the new millennium which was 18% of its original area. The principal driver of this environmental change has been the expansion of extensive smallholder agriculture. From 1988 to 2007, the area harvested in the GRF by smallholders of cocoa, cassava, and oil palm increased by 68,000 km². Field results suggest a high potential for significantly increasing crop yields through increased application of seed-fertilizer technologies. Analyzing land-use change scenarios, it was estimated that had intensified cocoa technology, already developed in the 1960s, been pursued in Cote d'Ivoire, Ghana, Nigeria and Cameroon that over 21,000 km² of deforestation and forest degradation could have been avoided along with the emission of nearly 1.4 billion t of CO₂. Addressing the low productivity of agriculture in the GRF should be one of the principal objectives of REDD climate mitigation programs.
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The time course and control of floral abscission and fruit set in Theobroma cacao were studied after spray application of growth regulators. 1-Naphthaleneacetic acid (NAA) prevented flower abscission in a concentration dependent manner and induced the early stages of fruit development. The cytokinin benzylaminopurine (BAP) counteracted NAA but resulted in longer fruit retention. Measurements of endogenous levels of indole-3-acetic acid showed an inverse correlation between the number of flowers per plant and auxin content. The results suggest that the genetic control of self-incompatibility in T. cacao may be modulated by the hormonal content of the flower.
Book
Tropical rainforests are disappearing due to agricultural intensification and climate change, causing irreversible losses in biodiversity and associated ecosystem functioning. Ecosystem properties and human well-being are profoundly influenced by environmental change, which is often not considered during land use intensification. Understanding these processes needs an integrated scientific approach linking ecological, economic and social perspectives at different scales, from the household and village level to landscapes and regions. The chapters in this book cover a broad range of topical research areas, from sustainable agroforestry management, climate change effects on rainforests and agroforests to integrated concepts of land use in tropical landscapes.
Article
The negative effects of climate change on cocoa production are often enhanced through agricultural intensification, while research institutions and enterprises try to minimize yield gaps with production strategies mitigating climate risk. Ecological intensification is such a production strategy, whereby yield increase is promoted through reduced agrochemical inputs and increased regulating ecosystem services such as pollination. However, we still know little about cocoa pollination ecology and services, although they appear to be key to understand yield functions. Here, we provide an extensive literature review on cocoa pollination focusing on three main aspects: non-plant (external) and plant regulated (internal) factors affecting pollination, pollinator agents, and ecological intensification management for enhancing pollination success and yield. Pollination services by many arthropod groups such as ants, bees, and parasitic wasps, and not only ceratopogonids, may be a way to increase cocoa productivity and secure smallholders income, but their role is unknown. Several environmental and socioeconomic factors can blur potential pollination benefits. Current knowledge gaps preclude our understanding of how to (i) identify the major pollinator species, (ii) disentangle the direct or indirect role of ants in pollination, (iii) design effective habitat improvements for pollination (by litter and shade management), and (iv) quantify the yield gaps due to pollination limitation. Optimizing cocoa pollination alone appears to be a powerful ecological tool to increase the yield of smallholders, but experimental research is required to validate these results in a realistic setting. In general, industry, governments and smallholders need to develop more joined efforts to ecological production strategies. In particular, farm-base management innovations based on robust scientific evidence must be designed to meet the increasing demand for chocolate and to mitigate cocoa yield gaps. This review suggests that diversified systems and associated ecosystem services, such as pollination, can help to achieve such goals.
Article
The unique benefits of wild pollinators to the productivity of agricultural crops have become increasingly recognized in recent decades. However, declines in populations of wild pollinator species, largely driven by the conversion of natural habitat to agricultural land and broad spectrum pesticide use often lead reductions in the provision of pollination services and crop production. With growing evidence that targeted pollinator conservation improves crop yield and/or quality, particularly for pollination specialist crops, efforts are increasing to substitute agriculturally intensive practices with those that alleviate some of the negative impacts of agriculture on pollinators and the pollination services they provide, in part through the provision of suitable pollinator habitat. Further, similarities between the responses of some pollinators and predators to habitat management suggest that efforts to conserve pollinators may also encourage predator densities. We evaluated the effects of one habitat management practice, the addition of cacao fruit husks to a monoculture cacao farm, on the provision of pollination services and the densities of two groups of entomophagous predators. We also evaluated the impacts of cacao fruit husk addition on pollen limitation, by crossing this habitat manipulation with pollen supplementation treatments. The addition of cacao fruit husks increased the number of fruits per tree and along with hand pollination treatments, increased final yields indicating a promotion of the pollination ecosystem service provided by the specialist pollinators, midges. We also found that cacao fruit husk addition increased the densities of two predator groups, spiders and skinks. Further, the conservation of these predators did not inhibit pollination through pollinator capture or deterrence. The findings show that with moderate habitat management, both pollinator and predator conservation can be compatible goals within a highly specialized plant-pollinator system. The effectiveness of this habitat manipulation may be attributable to the increased availability of alternative habitat and food resources for both pollinators and predators. The results exemplify a "win-win" relationship between agricultural production and biological conservation, whereby agricultural practices to support vital pollinators and pollination services can increase production as well as support species conservation. This article is protected by copyright. All rights reserved.
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Science is about discovering new things, about better understanding processes and systems, and generally furthering our knowledge. Deep in science philosophy is the notion of hypotheses and mathematical models to represent these hypotheses. It is partially the quantification of hypotheses that provides the illusive concept of rigor in science. Science is partially an adversarial process; hypotheses battle for primacy aided by observations, data, and models. Science is one of the few human endeavors that is truly progressive. Progress in science is defined as approaching an increased understanding of truth – science evolves in a sense.
Article
The abundance of several species of Forcipomyia midges (Diptera: Ceratopogonidae), known to be pollinators of cocoa Theobroma cacao increased markedly in one cocoa farm when discs of rotten banana stems were added to the ground-litter, but not in another. The increase in numbers of midge larvae and pupae associated with rotten banana stems occurred in a farm that had a shade cover consisting of an open canopy of bananas mixed with various wild trees, produced many cocoa flowers, and had a large number of midge species. The other farm had a uniform and homogenous shade cover of Hevea rubber trees, produced few cocoa flowers, and had only a few species of the midges.-from Author
Article
Human welfare is significantly linked to ecosystem services such as the suppression of pest insects by birds and bats. However, effects of biocontrol services on tropical cash crop yield are still largely unknown. For the first time, we manipulated the access of birds and bats in an exclosure experiment (day, night and full exclosures compared to open controls in Indonesian cacao agroforestry) and quantified the arthropod communities, the fruit development and the final yield over a long time period (15 months). We found that bat and bird exclusion increased insect herbivore abundance, despite the concurrent release of mesopredators such as ants and spiders, and negatively affected fruit development, with final crop yield decreasing by 31% across local (shade cover) and landscape (distance to primary forest) gradients. Our results highlight the tremendous economic impact of common insectivorous birds and bats, which need to become an essential part of sustainable landscape management.
Article
Ghana and Côte d’Ivoire are the world’s leading cocoa (Thebroma cacao) producing countries; together they produce 53 % of the world’s cocoa. Cocoa contributes 7.5 % of the Gross Domestic Product (GDP) of Côte d’Ivoire and 3.4 % of that of Ghana and is an important cash crop for the rural population in the forest zones of these countries. If progressive climate change affected the climatic suitability for cocoa in West Africa, this would have implications for global cocoa output as well as the national economies and farmer livelihoods, with potential repercussions for forests and natural habitat as cocoa growing regions expand, shrink or shift. The objective of this paper is to present future climate scenarios for the main cocoa growing regions of Ghana and Côte d’Ivoire and to predict their impact on the relative suitability of these regions for growing cocoa. These analyses are intended to support the respective countries and supply chain actors in developing strategies for reducing the vulnerability of the cocoa sector to climate change. Based on the current distribution of cocoa growing areas and climate change predictions from 19 Global Circulation Models, we predict changes in relative climatic suitability for cocoa for 2050 using an adapted MAXENT model. According to the model, some current cocoa producing areas will become unsuitable (Lagunes and Sud-Comoe in Côte d’Ivoire) requiring crop change, while other areas will require adaptations in agronomic management, and in yet others the climatic suitability for growing cocoa will increase (Kwahu Plateu in Ghana and southwestern Côte d’Ivoire). We recommend the development of site-specific strategies to reduce the vulnerability of cocoa farmers and the sector to future climate change.
Article
The use of pesticides for effective pests control has generated a lot of concerns relating to public health and environmental pollution. With the new European Union (EU) Legislation on Maximum Residue Levels (MRLs) allowed on cocoa beans and its products, efforts are now intensified to seek measures towards its reduction. The Cocoa Research Institute of Nigeria (CRIN) has the mandate to screen and recommend potential cocoa pesticides and spraying equipment in Nigeria. The Institute has screened and recommended many of these pesticides and equipment in the past. However, with the new EU Legislation on MRLs allowed on cocoa beans and products, some of the pesticides still undergoing screening and the previously recommended pesticides were banned. This new regulation, which came into effect September 1, 2008, has left very few pesticides for use on cocoa both on farm and post farm activities in Nigeria.
Article
Phenological patterns of flowering and fruit-set were studied in cocoa trees ( Theobroma cacao ) (Sterculiaceae) at monthly intervals in two contrasting habitats in Costa Rica for a one-year period. One of these habitats, a well-maintained plantation, had irregular and broken shade cover { Erythrina trees in particular) while in the other habitat, a ‘cocoa forest’, cocoa trees were heavily shaded by Huara crepitans (Euphorbiaceae). ‘Matina’ variety cocoa trees of about the same age (50–60 years) were censused in both habitats. Cocoa-pollinating midge (Diptera: Ceratopogonidae and Cecidomyiidae) availability was estimated by sampling immature stages in experimentally-distributed ground-cover breeding substrates, comparing overall abundances and species numbers between the two habitats over three census dates (dry, mid-rainy, and late-rainy seasons), along with examination of fungal-rotted (diseased) cocoa pods both on trees and the ground. Although total flower production was much greater in the plantation habitat, total production of new pods was similar between habitats. Flowering followed a cyclic temporal pattern in the forest but not in the plantation. Sudden leaf drop of forest shade trees in the dry season probably triggered a cyclic response in which flowering peaked in the first half of the rainy season. There was an inverse relation for frequencies of mature cocoa pods killed by squirrels and pathogenic fungi ( Monilia roreri and Phytophthora ) between the two habitats: squirrel-killed pods were far more abundant in the plantation than in the forest, and the opposite for fungus-killed pods. Fungus-killed but otherwise intact pods, and not squirrel-killed pods rotting on trees, were a major breeding site for midges, particularly during the late rainy season. Ceratopogonidae were most abundant in the dry season and frequently encountered in cocoa pod husks and banana tree trunk sections in both habitats, and much more so in the forest habitat. The abandoned cocoa plantation (cocoa forest) supported a more diverse assemblage of pollinating midges than the plantation. In the plantation but not in the forest, a negative correlation was discovered between distance from shade trees and the numbers of pods on trees, suggesting greater pollinating activity by midges in cocoa trees beneath shade trees than away from them. The uniform dense shade cover in the adjacent forest probably obliterated such a pattern.
Article
1. Agricultural intensification reduces ecological resilience of land-use systems, whereas paradoxically, environmental change and climate extremes require a higher response capacity than ever. Adaptation strategies to environmental change include maintenance of shade trees in tropical agroforestry, but conversion of shaded to unshaded systems is common practice to increase short-term yield. 2. In this paper, we review the short-term and long-term ecological benefits of shade trees in coffee Coffea arabica, C. canephora and cacao Theobroma cacao agroforestry and emphasize the poorly understood, multifunctional role of shade trees for farmers and conservation alike. 3. Both coffee and cacao are tropical understorey plants. Shade trees in agroforestry enhance functional biodiversity, carbon sequestration, soil fertility, drought resistance as well as weed and biological pest control. However, shade is needed for young cacao trees only and is less important in older cacao plantations. This changing response to shade regime with cacao plantation age often results in a transient role for shade and associated biodiversity in agroforestry. 4. Abandonment of old, unshaded cacao in favour of planting young cacao in new, thinned forest sites can be named ‘short-term cacao boom-and-bust cycle’, which counteracts tropical forest conservation. In a ‘long-term cacao boom-and-bust cycle’, cacao boom can be followed by cacao bust due to unmanageable pest and pathogen levels (e.g. in Brazil and Malaysia). Higher pest densities can result from physiological stress in unshaded cacao and from the larger cacao area planted. Risk-averse farmers avoid long-term vulnerability of their agroforestry systems by keeping shade as an insurance against insect pest outbreaks, whereas yield-maximizing farmers reduce shade and aim at short-term monetary benefits. 5. Synthesis and applications. Sustainable agroforestry management needs to conserve or create a diverse layer of multi-purpose shade trees that can be pruned rather than removed when crops mature. Incentives from payment-for-ecosystem services and certification schemes encourage farmers to keep high to medium shade tree cover. Reducing pesticide spraying protects functional agrobiodiversity such as antagonists of pests and diseases, pollinating midges determining cacao yields and pollinating bees enhancing coffee yield. In a landscape perspective, natural forest alongside agroforestry allows noncrop-crop spillover of a diversity of functionally important organisms. Knowledge transfer between farmers, agronomists and ecologists in a participatory approach helps to encourage a shade management regime that balances economic and ecological needs and provides a ‘diversified food-and-cash crop’ livelihood strategy.
Article
Cacao cultivation holds a sweet promise, not only for chocolate consumers and cacao farmers but also for conservationists who argue that diverse cacao agroforests may be used to sustain both livelihoods of smallholders and ecological benefits such as the conservation of biodiversity within human-dominated tropical landscapes. However, regional boom-and-bust cycles are the rule in global cacao production: after initial forest conversion to cacao agroforests, sustaining production is difficult due to dwindling yields as trees age and pest and disease pressure increases. The failure to revitalize plantations often leads to a shift of cacao production to other regions. Shade removal dynamics within these cycles substantially reduce most of the biodiversity benefits. We investigate the conservation implications of these processes. Using examples from the current cacao crisis in Indonesia, we show that until now commitments to sustainability by the cacao-chocolate sector have not been successful, which endangers remaining forests. Conservation can be combined with smallholder cacao production, but if this is to be achieved, greater quantitative and qualitative efforts to halt cacao cycles are needed on the part of the industry by making use of existing opportunities to combine sustainability, carbon storage, and biodiversity conservation.
Article
Intercropping is often promoted for effective mutualism between species, thus compensating for external inputs. However, for optimal farm design resulting in superior production and nutrition, an accurate assessment of plant inter- and intra-specific competition is required. In predominant shade tree-cocoa (Theobroma cacao) systems, inconclusive evidence remains on species interactions, limitations to resource availability and subsequent growth and nutritional response, particularly in early growth. We examined cocoa biomass and foliar nutrition as well as nutrient supply through rates of decomposition and N mineralization after 1-year growth. Our approach employed fertilization and mixed planting treatments in an additive design of cocoa in monoculture (control), under artificial shade, and intercropped under two separate shade species (Terminalia superba and Newbouldia laevis). Intercropping had no effect on cocoa biomass production in comparison to monoculture cocoa. However, artificial shading stimulated foliage and root production both with and without fertilization, suggesting strong effects of light regulation on growth in the absence of belowground competition. Nutritionally, intercropping suppressed K uptake in cocoa foliage as K concentration was reduced by 20–25%, signifying dilution of this nutrient, presumably due to interspecific competition for mobile elements. Foliar N content under N. laevis was raised, where N concentration kept up with growth under this intercropped species. Intercropping also delayed decomposition rates, suggesting slower but sustained release of available nutrients into the topsoil. Cocoa under artificial shade, both with and without fertilization, exhibited the greatest nutrient responses as compared to unfertilized monoculture cocoa, where P uptake was stimulated most (175 and 112%), followed by K (69 and 71%), and then N (54 and 42%). Intercropping with shade trees failed to increase cocoa biomass, however, nutrient uptake was sustained for N and P, suggesting low interspecific competition. When fertilizers are undesirable or unavailable, intercropping of appropriately selected shade trees will not competitively suppress early growth of cocoa but will improve light regulation and nutritional status of cocoa saplings.
Article
The mortality of cacao fruits caused by early fruit abortion or insect and pathogen attacks was investigated in differently managed agroforestry systems in Central Sulawesi, Indonesia. Nine agroforestry systems shaded by three different types of tree stands were selected, which represented a decrease in structural heterogeneity: forest remnants, diverse planted trees and one or two species of planted leguminose trees. After standardized manual cross-pollination, the development of 600 fruits on 54 trees (6 trees per agroforest) was followed during 18 weeks of fruit development. In total, 432 of all fruits were lost before maturity, which seriously undermined yields. The proportion of harvested fruits per tree (overall average: 27 ± 4%) was not affected by canopy type. Although shade cover did not have a significant effect, losses due to fruit abortion were most likely under forest shade, where nitrogen-fixing leguminose shade trees were absent. Fruit losses due to pathogenic infections and insect attacks increased with the homogenization of the agroforests, supporting the hypothesis that agricultural homogenization increases risks of pest outbreaks. In conclusion, shade management may be improved to increase yields from cacao using highly diversified natural shade agroforestry systems.
Article
Both pollination and resource limitation may cause low fruit:flower ratios in plants, but pollen and resource limitation have never been contrasted in commercially important crop species. Here we experimentally investigated the relative effect of pollen limitation and resource limitation in Theobroma cacao. In Central Sulawesi, Indonesia, we applied different relative levels of hand pollination (10%, 40%, 70% and 100% of available flowers up to 2 m height) to mature cacao trees in two separate experiments encompassing (1) different light (shade roofs) and nitrogen (fertilizer application) treatments, and (2) water availability (throughfall displacement) treatments. None of the resource availability treatments had a significant effect, while number of mature pods and yield increased non-linearly with pollination intensity up to 200% of current yield levels. The largest benefits were reached by increasing pollination from 10% to 40%, with non-significant increases beyond that level. Despite an increase of fruit abortion with pollination intensity, T. cacao yield is determined, at least on the short term, by the number of flowers pollinated. This suggests pollination deficit in crops can be very large and that a better knowledge of pollen and resource limitation to devise adequate pollinator management strategies may be critical for increasing production.
Article
Groups of 14-year-old cacao (Theobroma cacao L.) trees were hand pollinated, pollinated naturally or had their fruits continuously removed. Wilted and non-wilted cherelles (small fruits) were counted every 2 weeks, fallen flowers were counted weekly and mature pods were harvested monthly from 1983 through 1986. Carbohydrate, lipid and protein contents of wilted cherelles, mature pods and flowers were determined. Continuous removal of fruits caused a constant initiation of flowers and a significant increase in flowering intensity compared with the other treatments. The quantity of cherelles in the hand-pollinated trees was significantly greater than in the naturally pollinated trees. However, the number of mature fruits in both treatments was not statistically different because of increased cherelle wilting in the hand-pollinated trees. The continuously depodded trees allocated approximately 8 and 5 times more assimilate to flower production than the hand- and naturally pollinated trees, respectively. The naturally pollinated trees used only about one third as much energy for the production of flowers and wilted cherelles as the hand-pollinated trees, but about 1.4 times more energy than the depodded trees. It is concluded that fruit set in cacao is regulated by assimilate production and that cherelle wilting is the mechanism whereby the tree adjusts production.
Article
The recent trend to place monetary values on ecosystem services has led to studies on the economic importance of pollinators for agricultural crops. Several recent studies indicate regional, long-term pollinator declines, and economic consequences have been derived from declining pollination efficiencies. However, use of pollinator services as economic incentives for conservation must consider environmental factors such as drought, pests, and diseases, which can also limit yields. Moreover, "flower excess" is a well-known reproductive strategy of plants as insurance against unpredictable, external factors that limit reproduction. With three case studies on the importance of pollination levels for amounts of harvested fruits of three tropical crops (passion fruit in Brazil, coffee in Ecuador, and cacao in Indonesia) we illustrate how reproductive strategies and environmental stress can obscure initial benefits from improved pollination. By interpreting these results with findings from evolutionary sciences, agronomy, and studies on wild-plant populations, we argue that studies on economic benefits from pollinators should include the total of ecosystem processes that (1) lead to successful pollination and (2) mobilize nutrients and improve plant quality to the extent that crop yields indeed benefit from enhanced pollinator services. Conservation incentives that use quantifications of nature's services to human welfare will benefit from approaches at the ecosystem level that take into account the broad spectrum of biological processes that limit or deliver the service.
Practical Statistics for Data Scientists: 50+ Essential Concepts Using R and Python
  • P Bruce
  • A Bruce
  • P Gedeck
Bruce, P., Bruce, A., Gedeck, P., 2020. Practical Statistics for Data Scientists: 50+ Essential Concepts Using R and Python. O'Reilly Media.
Opportunity cost. The world of economics
  • J M Buchanan
Buchanan, J.M., 1991. Opportunity cost. The world of economics. Palgrave Macmillan, London.
The International Cocoa Organization
ICCO, 2018a. The International Cocoa Organization (accessed 2 May 2018). htt ps://www.icco.org/home/latest-news.html.
The International Cocoa Organization -Annual report
ICCO, 2018b. The International Cocoa Organization -Annual report 2014-2015 (accessed 2 May 2018). https://www.icco.org/about-us/icco-annual-report.html.
Our approach to sustainable cocoa
MARS, 2018b. Our approach to sustainable cocoa (accessed 2 May 2018). http://www. mars.com/global/sustainable-in-a-generation/our-approach-to-sustainability/ra w-materials/cocoa.
Tradeoffs between income, biodiversity, and ecosystem functioning during tropical rainforest conversion and agroforestry intensification
  • I Steffan-Dewenter
  • M Kessler
  • J Barkmann
  • M M Bos
  • D Buchori
  • S Erasmi
  • H Faust
  • G Gerold
  • K Glenk
  • S R Gradstein
  • E Guhardja
  • M Harteveld
  • D Hertel
  • P Höhn
  • M Kappas
  • S Köhler
  • K Leuschnerd
  • M Maertens
  • R Marggraf
  • S Migge-Kleian
  • J Mogea
  • R Pitopang
  • M Schaefer
  • S Schwarze
  • S G Sporn
  • A Steingrebe
  • S S Tjitrosoedirdjo
  • S Tjitrosoemito
  • A Twele
  • R Weber
  • L Woltmann
  • M Zeller
  • T Tscharntke
Steffan-Dewenter, I., Kessler, M., Barkmann, J., Bos, M.M., Buchori, D., Erasmi, S., Faust, H., Gerold, G., Glenk, K., Gradstein, S.R., Guhardja, E., Harteveld, M., Hertel, D., Höhn, P., Kappas, M., Köhler, S., Leuschnerd, K., Maertens, M., Marggraf, R., Migge-Kleian, S., Mogea, J., Pitopang, R., Schaefer, M., Schwarze, S., Sporn, S.G., Steingrebe, A., Tjitrosoedirdjo, S.S., Tjitrosoemito, S., Twele, A., Weber, R., Woltmann, L., Zeller, M., Tscharntke, T., 2007. Tradeoffs between income, biodiversity, and ecosystem functioning during tropical rainforest conversion and agroforestry intensification. Proc. Nat. Acad. Sc. U.S. 104, 4973-4978.
United Nations Framework Convention on Climate Change -Deforestation-free cocoa
UNFCCC, 2018. United Nations Framework Convention on Climate Change -Deforestation-free cocoa (accessed 2 May 2018). http://unfccc.int/mfc2015/defore station-free-cocoa/.
World Cocoa Foundation -Cocoa Action
  • Wcf
WCF, 2018. World Cocoa Foundation -Cocoa Action (accessed 2 May 2018). http://www .worldcocoafoundation.org/about-wcf/cocoaaction/.