Cacao Agroforestry Research Articles

Substantial Stem Methane Emissions From Rainforest and Cacao Agroforest Partly Negate Soil Uptake in the Congo Basin

AbstractMost stem CH4 emission investigations were conducted in wetland forests, and it remains unknown whether trees in tropical rainforests on heavily weathered soils are substantial contributors to ecosystem CH4 fluxes. Additionally, Africa remains the continent with the lowest numbers of published field studies on soil greenhouse gas fluxes. Over one year, we measured monthly stem and soil CH4 fluxes with forest conversion to traditional cacao agroforestry in the Congo Basin, Cameroon. All the measured trees emitted CH4 throughout the year. The annual total (soil + stem) CH4 fluxes were −2.62 ± 0.37 kg C ha−1 yr−1 from the forest and −3.23 ± 0.45 kg C ha−1 yr−1 for the cacao agroforestry, with stem CH4 emissions equating to 4%–21% of the soil sink in the forest, and 3%–27% of the soil sink in cacao agroforestry. 2% of our measured trees were “hot spots” of CH4 emission, with two orders of magnitude larger emissions than the remaining trees in our sites. Correlations of stem CH4 emissions and soil drivers suggest a potential belowground source of stem CH4 emissions, although this pathway may be working simultaneously with a within‐tree microbial CH4 source. Overall, forest conversion to traditional, mature cacao agroforestry did not affect stem and soil CH4 fluxes. Our results demonstrate that tropical trees on well‐drained, highly weathered soils represent potential CH4 emission pathways that have largely been ignored, and provides evidence that upland ecosystems may be weaker sinks of atmospheric CH4 than previously estimated.

Carbon dynamics in small tropical catchments under preserved forest and cacao agroforestry systems

Carbon dynamics in small tropical catchments under preserved forest and cacao agroforestry systems

Correction to: Who ate my chocolate? Small mammals and fruit damage in cacao agroforestry

Correction to: Who ate my chocolate? Small mammals and fruit damage in cacao agroforestry

Who ate my chocolate? Small mammals and fruit damage in cacao agroforestry

Who ate my chocolate? Small mammals and fruit damage in cacao agroforestry

Prediction model for sap flow in cacao trees under different radiation intensities in the western Colombian Amazon

In this study, we measured diurnal patterns of sap flow (Vs) in cacao trees growing in three types of agroforestry systems (AFs) that differ in the incident solar radiation they receive. We modeled the relationship of Vs with several microclimatic characteristics of the AFs using mixed linear models. We characterized microclimatic variables that may have an effect on diurnal patterns of sap flow: air relative humidity, air temperature, photosynthetically active radiation and vapor pressure deficit. Overall, our model predicted the differences between cacao Vs in the three different AFs, with cacao plants with dense Musaceae plantation and high mean diurnal incident radiation (HPAR) displaying the highest differences compared to the other agroforestry arrangements. The model was also able to predict situations such as nocturnal transpiration in HPAR and inverse nocturnal sap flows indicative of hydraulic redistribution in the other AFs receiving less incident radiation. Overall, the model we present here can be a useful and cost-effective tool for predicting transpiration and water use in cacao trees, as well as for managing cacao agroforestry systems in the Amazon rainforest.

Cacao agroforestry systems improve soil fertility: Comparison of soil properties between forest, cacao agroforestry systems, and pasture in the Colombian Amazon

The objective of our work was to evaluate soil quality in different cacao agroforestry systems (AFS) in the Colombian Amazon. We compared soil quality of AFS at the study site with soil quality of two control systems: a pasture and a secondary forest.The study was conducted at the Macagual Amazon Research Center in western Colombian Amazon. We set up eight 600 m² plots in each study system. We collected soil samples in each plot, and assessed macrofauna diversity, aggregate morphology, and physical and chemical soil properties. We integrated these variables in a General Indicator of Soil Quality (GISQ).We found GISQ values of 0.85 for forest, 0.5, 0.65 and 0.59 for AFS and 0.21 for pasture, and the values differed significantly between land uses. The establishment of cacao AFS on degraded pasture was found to significantly improve soil fertility, i.e., by 42%. The intensification level between land uses (Pasture > AFS > Forest) negatively affected macrofauna populations due to soil compaction (physical properties). Forest had the highest physical and biological quality.Our results show that AFS not only have the capacity to maintain key soil ecological functions, but also to restore soil quality of degraded pastureland. Cacao-based AFS could therefore be a key restoration strategy for degraded pastureland. These results are very important in the context of the Colombian Amazon, where cacao is currently known as the “crop of peace”.

Diet and observations on natural history of Gabohyla pauloalvini (Bokermann 1973) (Amphibia: Hylidae), a poorly known species from cacao agroforestry in southern Bahia, Brazil

Gabohyla pauloalvini is a small Neotropical hylid, known only from three localities besides its type locality. Knowledge about its natural history is scarce and we present the first data about its diet. We conducted our fieldwork during the rainy period between November and December of the years 2014 and 2015. Thirty-eight G. pauloalvini individuals, collected in a semi-permanent pond inside a “cabruca” (cacao plantation shaded by trees), municipality of Ilheus, Bahia, Brazil, were stomach-flushed. All stomach contents were identified to the lower taxonomic category as possible. The Index of Relative Importance (IRI) revealed that Formicidae was the most important prey category for G. pauloalvini. We assume that G. pauloalvini is an ant specialist. Diet records for others species of the tribe Sphaenorhynchini showed mainly ants as prey items, which reinforces an ecological synapomorphy for this tribe. Beyond diet, we also reported observations of possible parental care performed by G. pauloalvini females.

Stem and soil nitrous oxide fluxes from rainforest and cacao agroforest on highly weathered soils in the Congo Basin

Abstract. Although tree stems act as conduits for greenhouse gases (GHGs) produced in the soil, the magnitudes of tree contributions to total (soil + stem) nitrous oxide (N2O) emissions from tropical rainforests on heavily weathered soils remain unknown. Moreover, soil GHG fluxes are largely understudied in African rainforests, and the effects of land-use change on these gases are identified as an important research gap in the global GHG budget. In this study, we quantified the changes in stem and soil N2O fluxes with forest conversion to cacao agroforestry. Stem and soil N2O fluxes were measured monthly for a year (2017–2018) in four replicate plots per land use at three sites across central and southern Cameroon. Tree stems consistently emitted N2O throughout the measurement period and were positively correlated with soil N2O fluxes. 15N-isotope tracing from soil mineral N to stem-emitted 15N2O and correlations between temporal patterns of stem N2O emissions, soil–air N2O concentration, soil N2O emissions and vapour pressure deficit suggest that N2O emitted by the stems originated predominantly from N2O produced in the soil. Forest conversion to extensively managed, mature (>20 years old) cacao agroforestry had no effect on stem and soil N2O fluxes. The annual total N2O emissions were 1.55 ± 0.20 kg N ha−1 yr−1 from the forest and 1.15 ± 0.10 kg N ha−1 yr−1 from cacao agroforestry, with tree N2O emissions contributing 11 % to 38 % for forests and 8 % to 15 % for cacao agroforestry. These substantial contributions of tree stems to total N2O emissions highlight the importance of including tree-mediated fluxes in ecosystem GHG budgets. Taking into account that our study sites' biophysical characteristics represented two-thirds of the humid rainforests in the Congo Basin, we estimated a total N2O source strength for this region of 0.18 ± 0.05 Tg N2O-N yr−1.

Transportation can cancel out the ecological advantages of producing organic cacao: The carbon footprint of the globalized agrifood system of ecuadorian chocolate

Under the hypothesis that organically managed cacao agroforestry systems report a lower global warming potential (GWP) and reduce other environmental pressure indicators compared with conventionally managed systems and monocultures, this work discusses how global transportation can cut back the ecological advantage of the production phase. For this purpose, the life cycle assessment (LCA) of 1 kg of dark chocolate manufactured with Ecuadorian cacao has been performed (cradle-to-retailer approach), including the indirect impacts of transportation and estimating the equilibrium distances beyond which organic chocolate would have a higher impact than chocolate manufactured from cacao grown in monocultures and/or conventionally managed systems. To articulate the discussion, the carbon footprint (CF) of cacao/chocolate was analyzed together with 10 additional LCA-related impact categories. Three management systems—conventional monoculture (CM) and agroforestry (CA), and organic agroforestry (OA)—and three different supply chain scenarios with different weights in the transportation phase were studied. Expanding on the concept of “food miles”, the equivalent kilometers of the impact of emissions (km-eq) (or cumulated energy demand, eutrophication, etc.) were defined as the variable distance that a certain means of transportation can travel in relation to a fixed level of GHG emissions (or MJ, kg PO4-eq, etc.). The CF of the life cycle of cacao/chocolate was estimated at between 2.04 and 4.66 kg CO2-eq kg−1. The relative weight of transportation in relation to the total GHG emissions ranged between 8.9% and 51.1%, with cacao/chocolate traveling between 1380 and 9155 km-eq. The CF of chocolate made from cacao grown in OA systems was 22.7%–34.2% and 6.3%–10.7% lower than the CF of chocolate produced from cacao grown in CM and CA and manufactured and transported under the same conditions. The equilibrium distances between managements were estimated at 1213 and 5275 km-eq. Beyond those equivalent kilometers, organic chocolate would have a larger CF than chocolate manufactured from cacao grown, respectively, in CA and CM systems. Our results indicate that transportation would cancel out this and most other comparative ecological advantages of producing organic cacao analyzed in this work. Directly exporting chocolate from cacao-producing countries and relocating chocolate manufacture would help reduce GHG emissions and other environmental impacts of the supply chain.

The Practice of Co-Production through Biocultural Design: A Case Study among the Bribri People of Costa Rica and Panama

Research in co-production has given rise to a rich scientific literature in sustainability science. The processes by which co-production occurs are not well documented. Here, I present my work with the Bribri people to undertake a biocultural design project. Biocultural design is a process that begins with understanding participants’ aspirations to support their livelihoods. The process is collaborative, imagining ideas and executing products and services by drawing upon the capabilities of the participant’s biocultural heritage. In the Bribri territory, the biocultural heritage associated with cacao agroforestry systems is considered significant for Bribri livelihoods. Bribri people’s aspirations to grow cacao go beyond increasing cacao yields and include the respect for cultural teachings and social relationships. The participants of this project designed cacao value-added products (e.g., cacao jam, cacao butter) and services (e.g., showcase farm) by identifying viable ways to execute their ideas. Biocultural design offers a guide to co-imagine and co-execute ideas to solve specific problems and contributes to the practice of co-production by offering an approach that recognizes the value of science, while respecting the knowledge, aspirations and values of other actors.

Effects of agricultural systems on the anuran diversity in the Colombian Amazon

ABSTRACT We provide information on the diversity of anurans from agroforestry systems in the Colombian Amazon. This area is inserted at the tropical rainforest ecosystem and consists mainly of secondary forest remnants surrounded by crops, grasslands, and agroforestry systems. From February to May 2015, we sampled anurans mainly with visual and auditory surveys. We recorded a total of 1096 individuals of 20 species of anurans from six families at the study area. The relictual forest was the richest environment, followed by Achapo and Cacao agroforestry systems. The Achapo system showed great similarity in species composition with relictual forest; however, the latter presented the highest number of exclusive species, whereas the first presented only two and Cacao system did not have any exclusive species. Our results show that the richness can vary between the different types of agroforestry systems and highlight their importance as management tool for anurans conservation in the Colombian Amazon.

Unveiling Cacao Agroforestry Sustainability through the Socio-Ecological Systems Diagnostic Framework: The Case of Four Amazonian Rural Communities in Ecuador

Cacao cultivation is rapidly increasing in Latin America under the influence of public policies and external markets. In Ecuador, the cultivated surface of high quality cacao trees has doubled in the last 50 years, creating great expectations in neighboring countries. Here, we investigated the social-ecological sustainability of cacao-based agroforestry systems in four rural Amazonian highlands communities in eastern Ecuador, close to the region where cacao was once domesticated. Kichwa- and Shuar-speaking groups were interviewed by adapting Ostrom’s institutional diagnostic framework for social-ecological systems. Through a set of specifically created indicator variables, we identified key interactions and outcomes to understand the fragility and the sustainability of those communities. The studied communities were fairly young, with land rights secured less than 30 years ago in most cases. Per-family surfaces were very restricted (typically one hectare) and plots were divided between cash producing crops and their own home food. The small production per household goes through a precarious commercialization by both intermediaries and cooperatives, making the cacao bean production merely sufficient for pocket money. Ties with specialist producers in one community close to the capital has promoted the use of native cacao lines. Elsewhere, improved varieties of high productivity are planted along native trees being commercialized indistinctly. The continuity of these communities currently depend on a reorganization of their demography with parts of the population working elsewhere, as cacao bean production alone will continue to be insufficient, and will compete with their food self-sufficiency.

Cacao agroforestry management systems effects on soil fungi diversity in the Peruvian Amazon

Abstract Cacao agroforestry system provides productive land use and preserves the best conditions for physical, chemical and biological properties of tropical soils in cocoa tropical region of the world. We evaluated the impact of changing a 30-year-old native secondary forest to two cacao agroforestry systems on soil fungal diversity. The cacao agroforestry systems adapted were: an improved natural agroforestry system (INAS) where trees without economic value were selectively removed to provide 50% shade; and an improved traditional agroforestry system (ITAS) where all native trees were cut and burnt in the location. In both systems, new economically valuable trees were planted. In these management systems, plots of 10 cacao genotypes and one plot with a spontaneous cacao hybrid were selected for soil sampling. In each plot, soil samples were randomly collected at 0–20 cm depth, immediately after the trees were planted (2004) and at the end of 2010; each sample was divided in two, one part for soil characterization by conventional chemical analytical methods and the other for soil fungal analysis using the plate dilution method. Soil fungi were identified by appropriate keys and grouped according to their functionality as potential biocontrol, plant pathogenic, facultative or saprophytic fungi; the structure of fungal communities was analyzed by population, richness and Shannon and Simpson indices. Fungal diversity varied significantly during the years of study, at all soil depths and under the agroforestry systems assessed. The fungal communities showed significant changes due to soil management influenced by INAS and ITAS, and mainly after burning of native vegetation in ITAS. Overall higher abundance of soil fungal communities were observed in ITAS than in INAS. In both systems, differential changes in soil physical and chemical properties under cacao also could have been a contributing factor in the fungal diversity and functional groups observed.

Gendered Species Preferences Link Tree Diversity and Carbon Stocks in Cacao Agroforest in Southeast Sulawesi, Indonesia

The degree to which the maintenance of carbon (C) stocks and tree diversity can be jointly achieved in production landscapes is debated. C stocks in forests are decreased by logging before tree diversity is affected, while C stocks in monoculture tree plantations increase, but diversity does not. Agroforestry can break this hysteresis pattern, relevant for policies in search of synergy. We compared total C stocks and tree diversity among degraded forest, complex cacao/fruit tree agroforests, simple shade-tree cacao agroforestry, monoculture cacao, and annual crops in the Konawe District, Southeast Sulawesi, Indonesia. We evaluated farmer tree preferences and the utility value of the system for 40 farmers (male and female). The highest tree diversity (Shannon–Wiener H index 2.36) and C stocks (282 Mg C ha−1) were found in degraded forest, followed by cacao-based agroforestry systems (H index ranged from 0.58–0.93 with C stocks of 75–89 Mg ha−1). Male farmers selected timber and fruit tree species with economic benefits as shade trees, while female farmers preferred production for household needs (fruit trees and vegetables). Carbon stocks and tree diversity were positively related (R2 = 0.72). Adding data from across Indonesia (n = 102), agroforestry systems had an intermediate position between forest decline and reforestation responses. Maintaining agroforestry in the landscape allows aboveground C stocks up to 50 Mg ha−1 and reduces biodiversity loss. Agroforestry facilitates climate change mitigation and biodiversity goals to be addressed simultaneously in sustainable production landscapes.

Cacao agroforestry in Belize: Effects on soil nematode community structure

Cacao (Theobroma cacao L.) is a shade tolerant crop that can be grown beneath the rainforest canopy rather than in a conventional monoculture. Cacao agroforestry has been proposed as a more sustainable method of farming to mitigate climate change and protect above-ground biodiversity, yet impacts on soil biodiversity and function have rarely been investigated. Our goal was to study how the diversity and community structure of soil nematodes are impacted by planting the rainforest understory with cacao. At field sites in southern Belize and during two growing seasons, nematodes were extracted from soil from cacao agroforestry plots, undisturbed rainforests, and a banana plantation. Nematodes were enumerated and visually identified, and communities were analyzed using several community and diversity indices. In both the dry and wet seasons, soils from cacao plots contained similar nematode communities to the rainforest with respect to all measured variables, including the abundance of nematodes from each trophic group, the Bongers Maturity and Plant-Parasite indices, and the Shannon and Simpson’s diversity indices. In contrast, the banana plantation soils were dominated by plant-parasitic nematodes with lower Shannon and Simpson’s diversity indices. Overall, it appears that cacao agroforestry plots maintain nematode community structure relative to the undisturbed rainforest they were created from, suggesting that soil health is not compromised by this land-use strategy.

Cacao agroforestry systems do not increase pest and disease incidence compared with monocultures under good cultural management practices

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

The effects of forestry and agroforestry plantations on bird diversity: A global synthesis

AbstractThe increasing expansion of productive lands around the world during the last decades constitutes a strong driver of biodiversity loss, as they are usually established near to high diversity areas. Despite many studies that have compared bird diversity between natural and productive systems, a global synthesis is still missing and important for understanding how biodiversity is being altered. We conducted a meta‐analysis based on 144 case studies to assess the effects of four types of plantations (forestry, oil palm, coffee, and cacao) on bird species richness and abundance. We examined those effects in function of plantation type, latitudinal zone (temperate or tropical), geographical context (mainland or island), zoogeographic zone, and biodiversity hotspots. Plantations presented negative effects on both bird species richness and abundance. Oil palm plantations showed more negative effects followed by forestry plantations, whereas coffee and cacao agroforestry plantations had no significant effects. Those effects were geographically variable, being more pronounced in islands and temperate zones, as well as at the Oriental, Palearctic, and Neotropical zoogeograghic regions, and at the Sundaland and Mediterranean Basin biodiversity hotspots. Our results showed that productive systems reduce both species richness and abundance of bird species, being insular species particularly susceptible. Exotic monocultures with low structural heterogeneity (e.g., oil palm plantations) derive in highly impoverished bird communities dominated by generalist species. We identified South East Asia, tropical South America, and the Mediterranean Basin as the most threatened regions because of the sensitivity of their bird communities and the increasing rates of native forest replacement.

Effects of land tenure and urbanization on the change of land use of cacao (Theobroma cacao) agroforestry systems in southeast Mexico

Production of cacao and its products such as chocolate generate a global market. Despite demand, production has declined in a region historically important in the domestication of cacao in Mesoamerica. Chontalpa in southeast Mexico is an important area for cacao agroforestry systems, but a number of factors have affected current production, resulting in the elimination of many agroforestry systems. This study analyzes land use changes in the cacao production region of Tabasco State of SE Mexico using Landsat images from 2003 to 2016 to evaluate whether changes in cacao agroforestry systems into other land use forms are related to land tenure and distance to urban centers. Our results determined that land use changes were significantly lower in ejido lands, compared to other types of land tenure. A shorter distance to urban centers was associated with a higher probability of changing from cacao agroforestry systems to other land uses (grasslands, urban constructions). Members of young generations in the Chontalpa tend to move to urban centers that are continually growing at the expense of other land uses. Therefore, cacao agroforestry systems close to urban areas are more likely to change into this type of land use.

Deep soil carbon storage in tree-dominated land use systems in tropical lowlands of Kalimantan

Although carbon (C) stored deep in soils of tree-dominated land use systems in the tropics represents a large reservoir of organic matter its vulnerability to land use change has been hardly assessed. To fill this gap, we sampled Acrisols down to 3 m under three different land use systems; namely, recent cacao agroforestry (<2 years old; not deeper than 1 m), young and old rubber gardens (<10 years and >50 years), and secondary forest (>50 years) all located in Kapuas Hulu regency, West Kalimantan, Indonesia. We then assessed soil organic carbon (SOC) stocks as well as C accumulated in above- and belowground biomass, litter and dead wood debris at the soil surface. The amount of C stored in soils to a depth of 1 m exceeded the amount stored in living biomass (Σ C stored in roots, understorey and overstorey) strongly in the cacao agroforestry systems (69 Mg SOC vs. 12 Mg biomass-C ha−1), slightly in young rubber gardens (85 Mg SOC vs. 69 Mg C ha−1), but not in old rubber gardens (87 Mg SOC vs. 200 Mg C ha−1) and secondary forests (65 Mg SOC vs. 138 Mg C ha−1). Additionally in the older systems, up to 140 Mg C ha−1 (old rubber gardens) and 116 Mg C ha−1 (secondary forest) were found in soils to a depth of 3 m, thus raising soil C stocks by 60 to 80% relative to C stored in upper soil (0 to 1 m). We conclude that (1) the form of land use and land use change can substantially affect C stocks in living biomass, with aboveground biomass in old rubber gardens comparable to that of secondary forests; and (2) that land use change can reduce SOC in topsoil, but that substantial C stocks found in deep (down to 3 m) subsoil remain stable.

Stable carbon in soils under rubber tree (Hevea brasiliensis) agroforestry systems in the south of Bahia, Brazil

The early natural forest conversion to pasture, rubber tree plantations or agroforestry systems (AFSs) will not negatively affect soil organic carbon (SOC) accumulation due to the lack of soil tillage and the continuous contribution of vegetal residues to the soil, over the years, which would favor C occlusion in soil aggregates. The objectives of this study were: to evaluate the potential of AFSs with rubber trees to accumulate SOC up to 100 cm; to evaluate the δ13C variations over the soil profile after forest to pasture and rubber tree plantation (RTP) conversion; and to verify the C physical protection in aggregates as a mechanism of C stability in these soils. SOC was quantified up to 100 cm in whole soil and in three fraction-size classes (macroaggregates, microaggregates and silt + clay class). The occluded C was quantified in macro- and microaggregates by using an ultrasonic method. The relative contributions of C3 and C4 plants-derived C were quantified. The RTP system presented the highest SOC values, up to 100 cm depth, contributing with 20 Mg C ha−1 from belowground input, during 35-year old of system implantation. However, about 90% of SOC was not physically protected in the soil aggregates. The forest to rubber + cacao agroforestry system (AFS) conversion reduced SOC stock up to 100 cm approximately 72 Mg ha−1, and the reduction in SOC stock after forest to rubber tree + acai AFS was around 34 Mg ha−1. Rubber tree + cacao and rubber tree + acai AFSs had significant contributions of occluded C in soil aggregates.