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Meta-Analysis
. 2022 Feb;36(1):e13779.
doi: 10.1111/cobi.13779. Epub 2021 Aug 27.

Impact of cocoa agricultural intensification on bird diversity and community composition

Ruth E Bennett  1 , T Scott Sillett  1 , Robert A Rice  1 , Peter P Marra  2
Affiliations
Meta-Analysis

Impact of cocoa agricultural intensification on bird diversity and community composition

Ruth E Bennett et al. Conserv Biol. 2022 Feb.

Abstract
in English, Spanish

To meet the growing demand for chocolate, cocoa (Theobroma cacao) agriculture is expanding and intensifying. Although this threatens tropical forests, cocoa sustainability initiatives largely overlook biodiversity conservation. To inform these initiatives, we analyzed how cocoa agriculture affects bird diversity at farm and landscape scales with a meta-analysis of 23 studies. We extracted 214 Hedges' g* comparisons of bird diversity and 14 comparisons of community similarity between a forest baseline and 4 farming systems that cover an intensification gradient in landscapes with high and low forest cover, and we summarized 119 correlations between cocoa farm features and bird diversity. Bird diversity declined sharply in low shade cocoa. Cocoa with >30% canopy cover from diverse trees retained bird diversity similar to nearby primary or mature secondary forest but held a different community of birds. Diversity of endemic species, frugivores, and insectivores (agriculture avoiders) declined, whereas diversity of habitat generalists, migrants, nectarivores, and granivores (agriculture associates) increased. As forest decreased on the landscape, the difference in bird community composition between forest and cocoa also decreased, indicating agriculture associates replaced agriculture avoiders in forest patches. Our results emphasize the need to conserve forested landscapes (land sparing) and invest in mixed-shade agroforestry (land sharing) because each strategy benefits a diverse and distinct biological community.

Impacto de la Intensificación Agrícola del Cacao sobre la Diversidad y Composición de la Comunidad de Aves Resumen Para responder a la demanda creciente de chocolate, el cultivo de cacao (Theobroma cacao) se ha expandido e intensificado. Aunque esto es una amenaza para los bosques tropicales, las iniciativas de cacao sustentable en gran medida pasan por alto la conservación de la biodiversidad. Para proporcionar información a estas iniciativas, analizamos como la agricultura del cacao afecta a la diversidad de aves a escala de rancho y de paisaje mediante un metaanálisis de 23 estudios. Extrajimos 214 comparaciones de Hedges g* de la diversidad de aves y 14 comparaciones de la similitud de comunidades entre una línea de base de bosque y 4 sistemas de cultivo que cubren un gradiente de intensificación en paisajes con cobertura de bosque alta a baja, y sintetizamos 119 correlaciones entre características de cultivos de cacao y la diversidad de aves. La diversidad de aves declinó claramente en cultivos con poca sombra. Cultivos con >30% de cobertura de diversos árboles retuvieron una diversidad de aves similar a la de bosques primarios o maduros cercanos, pero presentaron una comunidad diferente. La diversidad de especies endémicas, frugívoras e insectívoras (evasoras de agricultura) declinó, mientras que la diversidad de generalistas de hábitat, migrantes, nectarívoras y granívoras (asociadas a agricultura) incrementó. A medida que decreció el bosque en el paisaje, la diferencia en la composición de la comunidad de aves entre bosque y cacao también decreció, lo que indica que las especies asociadas a la agricultura reemplazaron a las evasoras de la agricultura en los fragmentos de bosque. Nuestros resultados enfatizan la necesidad de conservar paisajes boscosos (conservación de tierras) e invertir en agroforestería de sombra mixta (compartición de tierras) porque cada estrategia beneficia a una comunidad biológica diversa y distinta.

Keywords: Aves; avian; biodiversidad; biodiversity; cacao; chocolate; conservación de tierras; farm; land sparing; meta-analysis; metaanálisis; sustainable; sustentable.

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Figures

FIGURE 1
FIGURE 1
Cocoa agriculture area by country overlaid by biodiversity hotspots and locations of studies used in meta‐analysis of cocoa impacts on bird diversity. Cocoa data from FAOstat (FAO, 2019)
FIGURE 2
FIGURE 2
Mean effect size differences in three bird biodiversity metrics between forest and four farming systems of increasing intensity (>0, greater biodiversity in the farm than forest; <0, less biodiversity in the farm than forest; ***, model estimate of Hedges’ g* significantly different from 0 at p< 0.001; model estimate tails, 95% CIs). Data compiled from 16 studies of biodiversity in cocoa.
FIGURE 3
FIGURE 3
Mean effect size differences in biodiversity metrics between forest and four farming systems of increasing intensity for nine bird guilds classified as (a) agriculture avoiders (endemic species, frugivores, and insectivores) when biodiversity is lower in agricultural systems than forest, (b) agriculture associates (habitat generalists, migrants, nectarivores, and granivores) when biodiversity is greater in agricultural systems than forest, and (c) neutral when no difference was recorded between forest and agriculture (>0, greater biodiversity in cocoa system than forest; <0, less biodiversity in cocoa system than forest; asterisks, estimated Hedges’ g* significantly different from 0 at *p< 0.05, **p< 0.01, or ***p < 0.001; model estimate tails, 95% CIs). Data compiled from 16 studies of biodiversity in cocoa.
FIGURE 4
FIGURE 4
Number of correlations (significant at p< 0.05) between bird biodiversity metrics and continuous habitat features managed on cocoa farms for (a) all birds, (b) guilds that avoid agriculture (endemics, frugivores, and insectivores), and (c) guilds associated with agriculture (generalists, migrants, granivores, and nectarivores) (>0, positive relationship; <0, negative relationship; italicized numbers, nonsignificant cases). Data compiled from 14 studies of biodiversity in cocoa.
FIGURE 5
FIGURE 5
Mean effect size differences in bird biodiversity metrics between forest and cocoa agriculture for all birds, guilds that avoid agriculture (endemics, frugivores, and insectivores), and agriculture associates (granivores, generalists, migrants, and nectarivores) in landscapes with high (>40%) and low (<40%) amounts of primary forest in a 10‐km radius around the study site (asterisks, estimated Hedges’ g* values significantly different between landscapes for each group at *p< 0.05 and ***p< 0.001; whiskers, 95% CIs around model estimates). Data compiled from 16 studies of biodiversity in cocoa.
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