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Hand pollination, not pesticides or fertilizers, increases cocoa yields and farmer income
Abstract and Figures
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. ...
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). ...
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. ...
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. ...
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.
... As a result, supplier transparency using block chain may be achieved, which has lately gained study attention and is now a recent research topic. For instance, Tian suggested a monitoring system for ASCs using bitcoin and radio frequency identification (RFID) technology, in which devices based on these two technologies are employed for data collection and storage, accordingly [3]. In addition, the author created another tracking system for ASCs utilizing blockchain, World Wide Web (IoT), and Risk Monitoring and Critical Control Points systems. ...
Customers spend for agro - based items made by farmers in agro - based supply chain operations (ASCs). People stress the significance of agri-food quality throughout this operation, while producers anticipate higher revenues. Effective tracing and governance for agri-food commodities encounter enormous hurdles as a result of the size and dynamism of ASCs. Nevertheless, the majority of the currently available solutions are unable to adequately address the accountability and administration needs of ASCs. First, in order to enable product tracing and provide organizational unit for the agri-food tracking data in ASCs, we develop a blockchain-based ASC architecture. The manufacturing and preservation of agri-food goods are then effectively decided in order to maximize profit using a Learning Based trainingbased Supply Chain Administration technology. To show the efficiency of the suggested cryptocurrency system and the DRSCM approach in various ASC contexts, detailed simulation tests are conducted. The findings indicate that the proposed ledger ASC architecture provides a strong assurance of trustworthy product traceability. Moreover, compared to intuitive and Q-learning approaches, the DR-SCM may provide larger product profitability.
... Shaded cacao agroforestry also facilitates native non-pest insects, including predatory insects such as ants, causing up to 34% yield gains (Wielgoss et al., 2014), and insectivorous birds and bats, which are also major biocontrol agents increasing yield by 30%-100% (Maas et al., 2016(Maas et al., , 2013Vansynghel, Ocampo-Ariza, Maas, Martin, Thomas, Hanf-Dressler, Schumacher, Ulloque-Samatelo, Tscharntke, et al., 2022). Pollinator populations are also a major leverage point to enhance cacao productivity, as very limited pollination success restricts yields (Vansynghel, Ocampo-Ariza, Maas, Martin, Thomas, Hanf-Dressler, Schumacher, Ulloque-Samatelo, Tschantke, et al., 2022;Chumacero de Schawe et al., 2013), shown by hand pollination, increasing yields by up to 200% (Groeneveld et al., 2010;Toledo-Hernández et al., 2020). Diversifying production systems with several native cacao varieties (Bennett, 2003) should increase pollination success due to the portfolio effect of higher pollen diversity (Paschke et al., 2002). ...
In the tropics, combining food security with biodiversity conservation remains a major challenge. Tropical agroforestry systems are among the most biodiversity‐friendly and productive land‐use systems, and 70% of cocoa is grown by >6 million smallholder farmers living on <2$ per day. In cacao's main centre of diversification, the western Amazon region, interest is growing to achieve premium prices with the conversion of high‐yielding, but mostly bulk‐quality cacao to native fine‐flavor cacao varieties, culturally important since pre‐Columbian times. Conversion to native cacao can be expected to favor adaptation to regional climate and growth conditions, and to enhance native biodiversity and ecosystem services such as biological pest control and pollination, but possibly also imply susceptibility to diseases. Experience from successful conversion of non‐native cacao plantations to fine‐flavor cacao agroforestry with rejuvenation by grafting and under medium‐canopy cover levels (30%–40%) can ensure a smooth transition with only minor temporary productivity gaps. This includes ongoing selection programs of high yielding and disease resistant native fine‐flavor cacao genotypes and organizing in cooperatives to buffer the high market volatility. In conclusion, the recent interest on converting bulk cacao to a diversity of native fine‐flavor varieties in countries like Peru is a challenge, but offers promising socio‐ecological perspectives.
... In some cases, these pests can cause annual crop losses of about 25-40 % (Wessel and Quist-Wessel, 2015) and even evolve resistances to chemical pesticides (Tabashnik and Johnson, 1999). Additionally, pesticides and other types of agrochemicals not only affect human health but can also cause negative collateral effects on the communities of insect pollinators (Nicolopoulou-Stamati et al., 2016;Vanbergen, Initiative, the I.P, 2013), which are fundamental for cacao pollination and productivity (Toledo-Hernández et al., 2020. Furthermore, Janssen and van Rijn (2021) showed that when natural enemies of pests are present, pesticides did not significantly reduce pest densities, highlighting the importance to consider nature-based solutions. ...
Central/West Africa is one of the most biodiverse regions on earth and one of the largest producers of cacao, producing about 68.4 % of the world's chocolate. Here, cacao pests and diseases can cause losses of $761 million annually. However, no studies from Africa have quantified the role of flying vertebrates as pest suppressors in cacao plantations. We used an exclusion experiment to prevent access of bats and birds to cacao trees for 12 months and quantified how their absence affected arthropod communities, herbivory, and cacao crop yield. Overall, important pests such as mealybugs and other hemipterans were more abundant in exclosures (9 and 1.6 times increase, respectively), despite potential multitrophic interactions with simultaneously increasing predatory arthropods such as spiders and mantis. Under heavy shade (90 %), cacao trees with flying vertebrate exclosures had 3.9 times fewer flowers and 3.2 times fewer large pods than control trees, corresponding to estimated losses on average of $478 ha⁻¹y⁻¹. Under low tree-level shade cover (10 %) however, the opposite pattern was evident: exclosure trees had 5.2 times more flowers and 3.7 times more large pods than control trees, corresponding to estimated savings on average of $796 ha⁻¹y⁻¹. We demonstrate that the enormous potential of African flying vertebrates as pest suppressors in cacao plantations is dependent on local shade tree management and only economically relevant above 50 % of shade. Despite higher productivity at low shade levels, our findings encourage African policymakers and farmers to adopt more high shade cacao agroforestry systems to maximize pest suppression services provided by bats and birds.
... Other studies conducted by Vera and Vera (2018), indicate that despite not having found significant differences between manual and natural technique in Criollo cocoa plantations, they reported differences between natural and assisted pollination in CCN-51 cocoa plantations, being higher in assisted pollination. In addition, Toledo-Hernández et al. (2020) report that manual pollination in Indonesia increases production up to 51% if 13% of the tree's flowers are pollinated, and could even increase up to 161% if 100% of the tree's flowers are pollinated, which, for the farmer, would be equivalent to a gain of up to 69%. Regarding the presence of Ceratopogonidae, five species were identified: Forcipomyia (Forcipomyia) quatei Wirth, Forcipomyia (Forcipomyia) youngi Wirth, Dasyhelea cacaoi Wirth & Waugh, Dasyhelea borgmeieri Wirth & Waugh, Culicoides pusillus Lutz, which were present in the three technological production levels and substrates in the three biological replicates. ...
The goal of this study was to evaluate the role of pollinators on the pollination, fertilization and fruit set process in three technological production levels and three reproduction substrates, determinants in cocoa yield. Two pollination techniques (natural and assisted) were compared and as a control, flowers were isolated with antiaphid. Twenty-seven observation units were formed, with three biological replicates. A known number of flowers were evaluated 6, 14, 21 and 36 days after the opening of each flower on marked branches. The number of active flowers, pollinated, fertilized and fruits formed was recorded. Pollinators present in experimental units were collected using yellow sticky cards, then taken to the lab and identified. Pollination occurred up to three days after opening, the flower that remained with the ovary swollen and attached to the branch/stem was considered pollinated. Fertilization was recorded fourteen days after flower opening, fruit set begins after fertilization, an event that was quantified twenty-one days after flower opening. The systems studied did not influence the percentage of pollination, fertilization and fruit formation. However, the substrates did influence pollination, fertilization and fruit set. The assisted pollination technique is significantly superior to natural pollination. The same species of Ceratopogonidae were reported at all three levels and substrates, with genera Forcipomyia and Dasyhelea being the most abundant.
... The growing demand for cocoa and decreasing yields due to climate change have led stakeholders in the cocoa production chain to seek multiple strategies regarding cocoa farming [12]. One such strategy is the cultivation of cocoa under agroforestry systems, providing a variety of foodstuffs for local farming families [13] and improving soil fertility by controlling and preventing soil erosion [14]. ...
One way to mitigate climate change is by reducing atmospheric CO2 levels with the establishment of agroforestry systems (AFSs) that can capture and store atmospheric CO2. This study therefore estimated the carbon sequestration in two components, aboveground (cocoa trees, other tree species, and leaf litter) and soil, in 15 fine aroma cocoa AFSs in Amazonas, Peru. These cocoa AFSs had a minimum area of 1.5 ha and were distributed into three age groups (each group consisted of five systems or farms): young cocoa trees between 8 and 15 years old, middle-aged cocoa trees between 16 and 29 years old, and adult cocoa trees between 30 and more than 40 years old. Generalized linear mixed model (GLMM) analysis followed by Fisher’s LSD mean comparison test (p > 0.05) determined the significant level of total aboveground biomass and total carbon content in the AFSs’ components. The present findings confirm that Theobroma cacao, Mussa sp., Cordia sp., and Persea sp. were the most common species in all AFSs. Clearly, biomass and carbon content in Theobroma cacao and Cordia sp. increased slightly with age, while fruit species Mussa sp. and Persea sp. decreased with age. The total aboveground carbon stock in young cocoa tree systems (13.64 Mg ha−1) was lower than in middle-aged cocoa systems (20.50 Mg ha−1) and adult cocoa systems (24.86 Mg ha−1); nevertheless, no significant differences were found for any of the age ranges. On the other hand, carbon stocks in soil (up to 30 cm depth) in the AFSs ranged from 119.96 Mg ha−1 to 131.96 Mg ha−1. Meanwhile, the total carbon stored by aboveground and soil components in adults cocoa systems (156.81 Mg ha−1) was higher compared to middle-aged cocoa systems (140.60 Mg ha−1) and young cocoa systems (133.59 Mg ha−1), although no statistically significant differences were found. Eventually, the CO2 sequestration for young cocoa systems was 490.28 Mg ha−1, and middle-aged and adult cocoa system recorded more than 500 Mg ha−1 of CO2. Furthermore, these data can further be used by national governments, local governments, and organisations of producers, particularly in accessing payments for environmental services, which may improve economic incomes and contribute to climate change mitigation by reserving biomass and sequestering C from these agroforestry cocoa systems.
... 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. ...
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. ...
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.
This project pursue to examine how blockchain technology can be appealed in the sector of supply chain management, beyond its common interconnection with cryptocurrencies. While technology is frequently interrelated with finance, it has several favorable applications in non-financial industries such as food and power. By make use of blockchain technology, it is feasible to generate enduring, attainable, and empirical data of products as they proceed through the supply chain. This improves the capability to track the products, guarantee their legitimacy and morality, and do so in a more cost-efficient manner. The possible advantages of using blockchain in agribusiness were also debated, as well as the case for executing a blockchain based small business in the automotive manufacturing industry. This project prefers to outline work of block chain technology in the field of supply chain. As an endeavor to cooperate with the physical one, we support a track of the journey of the supply chain products from producers to consumers. The user can access a complete documentation and confidence that the information is on target and precise. Block chain technology demonstrate to be useful in the supply chain zone in the following ways: diminish mistakes, reduce product retards, delete fraud activities, enhance management, improve consumer or supplier belief
Context: Different from general agriculture, tobacco agriculture in China adopts the production mode of farmers’ cooperatives to instruct farmers to engage in tobacco agricultural production under a policy of tobacco control. In addition to providing convenience for industry technical standardization, the policy goal aims to cope with the impact of production risk shocks and ultimately ensure the modernization and transformation of the tobacco industry and the stability of income of farmers. Objective: This study intends to explore the influence mechanism of the different degrees of cooperation and participation in cooperatives on the income of tobacco farmers from the perspective of risk shocks. Methods: Through the quantitative methods of the OLS regression model, hierarchical regression model and moderation model, this paper analyzes the data of 393 farmers engaged in tobacco agricultural production in Shaanxi Province obtained from survey and empirically analyzes the relationship between the degree of cooperation and participation in cooperatives and income. Interaction terms between risk shocks and cooperation are introduced to verify the regulatory effect of participation in tobacco farmers’ professional cooperatives on mitigating risk shocks and improving agricultural income. Results and conclusions: The results show that while risk shocks, including natural risks, market risks and policy risks, negatively affect the income of tobacco farmers, the degree of cooperation and participation has a significant positive effect on the income of tobacco farmers, and the degree of peasant households’ participation in the professional cooperative of tobacco farmers as a moderator variable has a regulatory effect on mitigating the impact of risk shocks on the income of tobacco farmers. The mechanism of action is that tobacco farmers participate in cooperatives to a higher degree, which can further promote the association of farmers and jointly resist risk shocks by reducing production costs, improving the technical level, and strengthening risk prevention and other measures to improve the income level. Significance: It would be helpful to encourage tobacco farmers to take the initiative to participate in the daily management‐related affairs and decisions of cooperatives, strengthen technical training, obey cooperative management, and actively respond to cooperative policies to effectively resist risk shocks and stabilize farmers’ income level and family welfare.
Spring ephemeral plants that experience harsh environments have developed specific reproductive characteristics. These characteristics are of great importance to the survival and reproduction of these species, particularly for rare and endangered plants. Fritillaria is a genus consisting of spring ephemeral plants with significant medicinal and ornamental value whose wild resources are highly threatened and whose reproductive characteristics and adaptative evolutionary mechanisms are still not well understood. Fritillaria maximowiczii is positioned at the most basal clade on the Fritillaria phylogenetic tree, whose reproductive characteristics remain obscure. In this study, we report the flowering dynamics, pollination biology and breeding system of F. maximowiczii. The flowering process of F. maximowiczii can be divided into seven stages. Based on the pollen/ovule ratio, the outcrossing index and a field pollination experiment on a natural population, F. maximowiczii showed high levels of outcrossing and self-compatibility. Three types of pollinators were observed: two kinds of bumblebees, and spiders. Diverse herkogamy and dichogamy may have considerably improved its reproductive success rate. Furthermore, a special reproductive mode not previously reported in wild populations of Fritillaria, apomixis, was strongly suspected based on a high fruit setting rate (36.84%). Our study suggests F. maximowiczii has developed multiple reproductive strategies to adapt to harsh environments and ensure population reproduction, and the diverse reproductive mechanisms may be related to its primitive phylogenetic position in the genus. This study not only broadens our understanding of mechanisms of ecological adaptation in spring ephemeral plants but also provides key data for the conservation of Fritillaria.
Cocoa (Theobroma cacao L.), a major commodity globally, depends on insects for pollination. However, the cocoa pollinator identity is largely unknown and there are important knowledge gaps regarding landscape and farm-level management driving pollinators. Here we analyzed flower visitation with two approaches to quantify how landscape and farm-level factors affect potential pollinators (flower visitors) of cocoa in Central Sulawesi, Indonesia. In the first approach (landscape and farm-level) we selected 18 farms and focused on the relative importance of distance to forest (m), potential-pollinator habitats surrounding the farm (i.e. secondary forests and cocoa agroforests [%]), canopy cover (%), leaf-litter amount (kg/m²), and cocoa flower abundance for flower visitors. In the second approach (experimental farm management) we manipulated leaf-litter in 24 farms, because high leaf-litter is suggested to enhance flower visitors. We found that ants and Diptera were the most common flower visitors, and although previous studies suggest ceratopogonids as main cocoa pollinators, none were captured in this study. In the landscape and farm-level approach, potential-pollinator habitats surrounding the farm, and increased canopy cover enhanced ant and Diptera abundance, whereas distance to forest had no effect. In the experimental farm management approach, potential-pollinator habitats surrounding the farm rather than leaf-litter manipulation increased Diptera and ant abundance. In summary conservation of forests and agroforests surrounding the farm, maintaining canopy cover and minimum leaf-litter enhance cocoa flower visitors. Thus, farms with shade trees embedded in a biodiversity-friendly landscape are important for conservation of potential pollinators and pollination services and, thereby, promotion of sustainable cocoa.
In agri-food supply chains (ASCs), consumers pay for agri-food products produced by farmers. During this process, consumers emphasize the importance of agri-food safety while farmers expect to increase their profits. Due to the complexity and dynamics of ASCs, the effective traceability and management for agri-food products face huge challenges. However, most of the existing solutions cannot well meet the requirements of traceability and management in ASCs. To address these challenges, we first design a blockchain-based ASC framework to provide product traceability, which guarantees decentralized security for the agri-food tracing data in ASCs. Next, a Deep Reinforcement learning based Supply Chain Management (DR-SCM) method is proposed to make effective decisions on the production and storage of agri-food products for profit optimization. The extensive simulation experiments are conducted to demonstrate the effectiveness of the proposed blockchain-based framework and the DR-SCM method under different ASC environments. The results show that reliable product traceability is well guaranteed by using the proposed blockchain-based ASC framework. Moreover, the DR-SCM can achieve higher product profits than heuristic and Q-learning methods.
Natural enemy is an important factor in management of cacao pests. One way to increase its diversity and abundance is through agroecosystem management techniques that support. The study was conducted for one year from February 2014 to February 2015 in Banjarsari Plantation and a cocoa farm of Kaliwining Experimental Station, Jember, which applied different cropping patterns and use of insecticides. The purpose of this research was to study the effect of cropping pattern and use of insecticide on diversity and abundance of predators, parasitoids, abundance and intensity of Helopeltis antonii attack. Observation of pests and natural enemies was done visually, using sweep net, yellow pan traps, malaise trap and pifall trap. Intensity of the attack used Pedigo & Buntin equations. Diversity index used Shannon Diversity Index (H’) and Simpson’s dominance index (C). Differences in predator abundance, parasitoid, air temperature, relative humidity, light intensity and rainfall used Wilcoxon test. Results of this study showed that monoculture and intensive use of synthetic insecticides caused lower diversity and abundance of predators and parasitoids, while the abundance and intensity of H. antonii attacks were higher compared with polyculture without insecticide. Banjarsari cocoa plantation that applied monoculture and intensive use of synthetic insecticides, had lower diversity and abundance predators and parasitoids compared with cocoa plantation in Kaliwining that applied polyculture planting without using insecticide. Dominant predators in Banjarsari and in Kaliwining cocoa plantations were Dolichoderus thoracicus and Araneus diadematus, while dominant parasitoid in Banjarsari and in Kaliwining cocoa plantations was Araneus diadematus.
Meeting demands for agricultural production while maintaining ecosystem services, mitigating and adapting to climate change and conserving biodiversity will be a defining challenge of this century. Crop production in agroforests is being widely imple- mented with the expectation that it can simultaneously meet each of these goals. But trade-offs are inherent to agroforestry and so unless implemented with levels of canopy cover that optimize these trade-offs, this effort in climate-smart, sustainable intensification may simply compromise both production and ecosystem services. By combining simultaneous measurements of production, soil fertility, disease, climate variables, carbon storage and species diversity along a shade-tree cover gradient, here we show that low-to-intermediate shade cocoa agroforests in West Africa do not compromise production, while creating benefits for climate adaptation, climate mitigation and biodiversity. As shade-tree cover increases above approximately 30%, agroforests become increasingly less likely to generate win–win scenarios. Our results demonstrate that agroforests cannot simultaneously maximize production, climate and sustainability goals but might optimise the trade-off between these goals at low-to-intermediate levels of cover.
Count data can be analyzed using generalized linear mixed models when observations are correlated in ways that require random effects. However, count data are often zero-inflated, containing more zeros than would be expected from the typical error distributions. We present a new package, glmmTMB, and compare it to other R packages that fit zero-inflated mixed models. The glmmTMB package fits many types of GLMMs and extensions, including models with continuously distributed responses, but here we focus on count responses. glmmTMB is faster than glmmADMB, MCMCglmm, and brms, and more flexible than INLA and mgcv for zero-inflated modeling. One unique feature of glmmTMB (among packages that fit zero-inflated mixed models) is its ability to estimate the Conway-Maxwell-Poisson distribution parameterized by the mean. Overall, its most appealing features for new users may be the combination of speed, flexibility, and its interface's similarity to lme4.
The Indonesian cocoa sector has experienced tremendous growth in the past twenty five years with massive growth, driven by rapid expansion of smallholder farmer participation. Cocoa production provides the main source of income of millions smallholder farmers and their families in Indonesia. Smallholders contribute more than ninety percent of national production; the remainder comes from state-owned plantations and private estates. In parts of Indonesia, cocoa is responsible for the opening up of primary forests and the establishment of settlements in these previously forested areas. Cocoa intensification system, which increases the fragmentation of primary forests and is considered agriculturally unsustainable, is becoming common in Indonesia. This paper presents the synthesis that resulted from this review as well as the researcher’s critical appraisal of the state of the research field of intensification system and its effect under climate change which the objective remaining stakeholder relevant to the sustainable intensification of farming practices of the poor smallholder farmers in Indonesia.
The production of tropical agricultural commodities, such as cocoa (Theobroma cacao) and coffee (Coffea spp.), the countries and communities engaged in it, and the industries dependent on these commodities, are vulnerable to climate change. This is especially so where a large percentage of the global supply is grown in a single geographical region. Fortunately, there is often considerable spatial heterogeneity in the vulnerability to climate change within affected regions, implying that local production losses could be compensated through intensification and expansion of production elsewhere. However, this requires that site-level actions are integrated into a regional approach to climate change adaptation. We discuss here such a regional approach for cocoa in West Africa, where 70 % of global cocoa supply originates. On the basis of a statistical model of relative climatic suitability calibrated on West African cocoa farming areas and average climate projections for the 2030s and 2050s of, respectively, 15 and 19 Global Circulation Models, we divide the region into three adaptation zones: (i) a little affected zone permitting intensification and/or expansion of cocoa farming; (ii) a moderately affected zone requiring diversification and agronomic adjustments of farming practices; and (iii) a severely affected zone with need for progressive crop change. We argue that for tropical agricultural commodities, larger-scale adaptation planning that attempts to balance production trends across countries and regions could help reduce negative impacts of climate change on regional economies and global commodity supplies, despite the institutional challenges that this integration may pose.
This paper reviews the present condition of cocoa growing in West Africa where some six million ha are planted with cocoa which provide about 70 percent of the total world production. Côte d’Ivoire and Ghana are the largest producers, followed by Nigeria and Cameroon. In the beginning of the 21st century the cocoa production increased from about 2,000,000 tons to about 3,000,000 tons in 2010 and subsequent years. While in this period expansion of the cocoa area (at the expense of forest land) contributed to increased production, nowadays more cocoa has to come from higher yield per ha which is very low at present. This paper highlights at first cocoa growing in each of the cocoa producing countries and then deals with the common constraints and options to higher yields, especially those in Côte d’Ivoire and Ghana. The major causes of low yield are a high incidence of pests and diseases, the old age of cocoa farms and lack of soil nutrients.
Cocoa is strictly entomophilous but studies on the influence of the ecosystem on insect pollinators in cocoa production systems are limited. The abundance of cocoa pollinators and pod-set of cocoa as influenced by a gradient of farm distances from natural forest and proportion of plantain/banana clusters in or adjacent to cocoa farms were therefore investigated. Cocoa pollinators trapped were predominantly ceratopogonid midges hence, analyses were based on their population. Variation in farm distance to forest did neither influence ceratopogonid midge abundance nor cocoa pod-set. However, we found a positive relationship between pollinator abundance and pod set and the proportion of plantain/banana intercropped with cocoa. The results suggest appropriate cocoa intercrop can enhance cocoa pollination, and the current farming system in Ghana can conveniently accommodate such interventions without significant changes in farm practices.
Cited By (since 1996):17, Export Date: 26 November 2013, Source: Scopus
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.
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).
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.
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.
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.
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.
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.
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.
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.
Losses of biodiversity and ecosystem functioning due to rainforest destruction and agricultural intensification are prime concerns for science and society alike. Potentially, ecosystems show nonlinear responses to land-use intensification that would open management options with limited ecological losses but satisfying economic gains. However, multidisciplinary studies to quantify ecological losses and socioeconomic tradeoffs under different management options are rare. Here, we evaluate opposing land use strategies in cacao agroforestry in Sulawesi, Indonesia, by using data on species richness of nine plant and animal taxa, six related ecosystem functions, and on socioeconomic drivers of agroforestry expansion. Expansion of cacao cultivation by 230% in the last two decades was triggered not only by economic market mechanisms, but also by rarely considered cultural factors. Transformation from near-primary forest to agroforestry had little effect on overall species richness, but reduced plant biomass and carbon storage by ≈75% and species richness of forest-using species by ≈60%. In contrast, increased land use intensity in cacao agroforestry, coupled with a reduction in shade tree cover from 80% to 40%, caused only minor quantitative changes in biodiversity and maintained high levels of ecosystem functioning while doubling farmers' net income. However, unshaded systems further increased income by ≈40%, implying that current economic incentives and cultural preferences for new intensification practices put shaded systems at risk. We conclude that low-shade agroforestry provides the best available compromise between economic forces and ecological needs. Certification schemes for shade-grown crops may provide a market-based mechanism to slow down current intensification trends.
• agricultural economics
• agroforestry management
• land use change
• plant–animal interactions
• ecosystem goods and services
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.
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.
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.
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.
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
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.
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.
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.
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.
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.
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.
1. Although agricultural expansion is a primary threat to tropical biodiversity, experimental studies evaluating the conservation value of tropical agricultural habitats are scarce. In particular, little is known about the sensitivity of amphibians and reptiles to habitat disturbance in areas of very high diversity such as South-East Asia.
2. We used a two-step approach to determine the relationship between habitat complexity and conservation value of cacao agroforestry for herpetological diversity in Sulawesi (Indonesia). Indonesia is the third largest cacao-exporting country globally and forest conversion to cacao plantations is a major threat to its biodiversity. We first sampled 43 cacao plantations six times to determine the environmental variables that best explained herpetofaunal diversity patterns using a Bayesian model selection approach. Based on these results, we experimentally manipulated leaf litter thickness (LLT), number of branch piles (LOGS) and LLT + LOGS combinations in the cacao plots. The experimental data were analysed using Bayesian hierarchical regression.
3. The best supported correlative models incorporated LLT, LOGS, air temperature and the ratio between leaf litter and shrub cover, showing the importance of habitat heterogeneity and suggesting climate change sensitivity. The subsequent structural manipulation of these attributes changed amphibian and reptile species richness, and reptile abundance, but only addition of leaf litter did so in a biologically meaningful way, providing microhabitat resources. However, the main beneficiaries were common disturbance-tolerant reptiles.
4. Synthesis and applications. The different results from the correlative model and the independent manipulative experiments showed how important such a combined approach is to derive adequate conservation management recommendations. Increasing leaf litter in cacao agroforestry will work best if implemented on a landscape scale to incorporate sufficient environmental variation and species life histories. This will mainly enhance the richness and abundance of disturbance-tolerant species, which still may maintain ecosystem functions such as pest removal. Particularly for rare species, native forests remain critical for herpetological richness. The direct temperature sensitivity suggests that future climate change impacts may be severe for herpetological diversity in plantation habitats and, hence, demand further research.
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.
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.
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.
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.
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/.
Practical Statistics for Data Scientists: 50+ Essential Concepts Using R and Python
- Bruce