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Multistrata Systems: Potentials and Challenges of Cocoa-based Agroforests in the Humid Tropics

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Abstract

Multistrata agroforests comprise a wide range of agroforestry practices that includes assemblage of woody and nonwoody plant components, with the wide range of practices on the continuum from using shade trees in perennial plantation to very diversified agroforests that mimic the original forest-like structure. In the humid tropical lowlands, such systems often consist of cocoa (Theobroma cacao) grown under the shade of trees. In this review, we explore the reliability of research on and the feasibility of achieving the environmental and economic benefits of cocoa agroforests, highlighting future opportunities and challenges of cocoa growing. Unsustainable intensification in a form of monocultures with high agricultural inputs reduces ecological resilience of a land-use system, whereas paradoxically, environmental and climate changes require more than ever a higher capacity of land-use systems to cope with increasing global environmental pressure. Over the past decade, a number of new studies focusing on cocoa agroforests have been published. We review current cultivation of cocoa in the world and outline the establishment and management of cocoa agroforests. Further on, we explored the idea that cocoa agroforests could be a solution to prevent phenomenon of boom-and-bust cycle of cocoa cultivation and highlighted the possibilities for improvement of cocoa cultivation using its vast genetic base. Then the benefits of cocoa agroforests for (agro)biodiversity and soil conservation are summarized and economic perspectives of multistrata systems assessed. In final discussion, we performed a SWOT analysis, highlighting future opportunities and challenges and proposing recommendation to improve the extension, adoption and sustainability of cocoa agroforests.
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... Cacao (Theobroma cacao, L.) agroforestry systems (CAFS), in which cacao grows under one or more tree species, are a biodiverse alternative to monoculture production. Integration of shade trees provides ecosystem services such as carbon sequestration, preservation of biodiversity, and pest management, although in some cases these may come at the expense of short-term productivity [1][2][3]. Shade trees benefit cacao by favorably modifying the microclimate: buffering temperature extremes and wind, decreasing erosion locally, and reducing incoming light to avoid unwanted vegetative growth [4]. ...
... The present study sought to (1) understand how presence and identity of diverse shade trees impacts soil physical, chemical, and microbial characteristics in the adjacent cacao rhizosphere; and (2) characterize direct and indirect relationships among shade trees, soil abiotic properties, microbial communities, and cacao yields. We hypothesized that shade tree presence and species identity would directly impact cacao yields ( Figure 1). ...
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Cacao agroforestry systems offer the potential to diversify farmer income sources, enhance biodiversity, sequester carbon, and deliver other important ecosystem services. To date, however, studies have emphasized field- and system-scale outcomes of shade tree integration, and potential impacts on the rhizosphere of adjacent cacao trees have not been fully characterized. Interactions at the root–soil interface are closely linked to plant health and productivity, making it important to understand how diverse shade tree species may affect soil fertility and microbial communities in the cacao rhizosphere. We assessed the impacts of neighboring shade tree presence and identity on cacao yields and physical, chemical, and biological components of the cacao rhizosphere in a recently established diversified agroforestry system in South Sulawesi, Indonesia. Stepwise regression revealed surprising and strong impacts of microbial diversity and community composition on cacao yields and pod infection rates. The presence of neighboring shade trees increased nitrogen, phosphorus, and pH in the rhizosphere of nearby cacao trees without yield losses. Over a longer time horizon, these increases in rhizosphere soil fertility will likely increase cacao productivity and shape microbial communities, as regression models showed nitrogen and phosphorus in particular to be important predictors of cacao yields and microbiome diversity and composition. However, neither presence nor identity of shade trees directly affected microbial diversity, community composition, or field-scale distance-decay relationships at this early stage of establishment. These results highlight locally specific benefits of shade trees in this agroecological context and emphasize the rhizosphere as a key link in indirect impacts of shade trees on cacao health and productivity in diversified systems.
... During the past two or three decades, ecological considerations have emerged on the cocoa agenda (Schroth et al. 2004;Jiménez and Beer 1999;Neisten et al. 2004;Rice and Greenberg 2000;Shapiro and Rosenquist 2004;Harvey et al. 2006;Sonwa et al. 2014;Armengot et al. 2016;Blaser et al. 2018;Lojka et al. 2017;Mortimer et al. 2017). Environmental considerations emerged in particular, due to the fact that cocoa fields are being set up on land that was previously forest (Mossu 1990;Champaud 1966) and also because these farming systems are sometimes part of the forest landscapes or part of a matrix in which forest is mixed with farming systems (Leplaideur 1985;ASB 2000;Gockowski and Weise 1999). ...
... With this dynamic present on the cocoa agenda, plants associated with cocoa appear to be one of the main preoccupations of many stakeholders. These trees are intended to provide shade to cocoa trees, provide products (timber and non-timber) to farmers and national economies, and also provide ecological services such as biodiversity conservation and climate change mitigation (Sonwa et al. 2001(Sonwa et al. , 2010FAO 2002;Lojka et al. 2017). ...
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Cocoa agroforests are growing in importance with a view to meeting farmers’ livelihood goals as well as ecological services. Following the recognition of cocoa agroforests as being useful for biodiversity conservation and farmers’ livelihoods, there is a growing discourse on the fact that they may also be useful in climate change mitigation and biodiversity conservation. Several companies have expressed their willingness to be “deforestation” certified within the next two decades. In West and Central Africa, cocoa is part of the endeavour to contribute to the REDD+ mechanism. Besides producing cocoa beans, the additional expectations from cocoa agroforests (timber, NWFP, biodiversity conservation, carbon storage, etc…) depend on the trees associated with the cocoa plants. The manner in which associated trees are mixed in the system impacts on the cocoa plants and plants associated with cocoa trees within the agroforestry system thus impact on the products and services produced by these farming systems. Studies are being undertaken to identify the exact composition of these associated trees but very few deal with the manner in which these trees are structurally distributed—vertically and horizontally—within the cocoa agroforest. Understanding the way in which cocoa and non-cocoa trees are distributed within the system would be useful with a view to improving the farm system, thus meeting the needs of several stakeholders. The present study reviews the structure of cocoa orchards and agroforests in West and Central Africa (Cameroon, Nigeria, Ghana and Cote d’Ivoire) with a view to improving the products and services of cocoa landscapes. This review is centred around: (i) density of cocoa, (ii) density of associated plants, (iii) basal area or associated plants, (iv) stratification and space between components, and (v) the life cycle of cocoa plantation components.
... Cocoa (Theobroma cacao L.), one of the major world cash crops (Hosseini-Bai et al. 2019), is traditionally grown in agroforestry systems . The carbon storage potential of these systems should be studied (Lojka et al. 2017) for several reasons. First, their management intensity directly affects stand composition and structural complexity . ...
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In the perspective of using cocoa as a response to climate change, a preliminary carbon stock assessment was conducted in cocoa agroforests of the Bengamisa-Yangambi forest landscape in the north-east of Democratic Republic of Congo (DRC). Data were collected in 25 plots of 2500 m2 each, spread over 16 villages. Above-ground carbon stock assessment on cocoa trees and their associated plants revealed that cocoa agroforests store on average 44.48 Mg ha−1 of above-ground carbon of which, cocoa-associated plants represent 83.68%. The diversity (species richness) of cocoa associated plants determine the level of above-ground carbon stored in cocoa agroforests. Trees less than 50 cm in diameter stored a larger amount of above-ground carbon. Cocoa agroforests with associated plants dominated by forest species (Model F) store 1.76 and 1.72 times more carbon, respectively, than those where associated plants are dominated by oil palm (Model P) and a mixture of plant types (forest species mixed with oil palm plants, or Model FP). Associated plants inside cocoa agroforests also play additional roles to support livelihoods such as health care, household consumption and timber. Therefore, beyond carbon storage, cocoa agroforest is an important reservoir of some local species and thus useful for biodiversity conservation and local livelihoods. As cocoa agroforests in DRC are recognized as one of the main responses to climate change, this study constitutes an early contribution to the process of reducing emissions from deforestation and forest degradation (REDD +) in forest landscapes in this country of the Congo Basin.
... However, there are numerous concerns regarding the unsustainability of high yields from unshaded monocropped cocoa, especially due to the ecological collapse of cocoa production in the Atlantic Coast area of Brazil, which resulted in witches' broom disease and an economic crisis [57,58]. One solution that has been proposed is the establishment of multi-strata cocoa agroforests for greater ecological stability [43,59,60]. This more holistic approach includes the adoption of ecological science, farmers' objectives, and appropriate policies to sustain agricultural production [8] based on the principle of "land-maxing" [7]. ...
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