Data from: How ants, birds and bats affect crop yield along shade gradients in tropical cacao agroforestry

Tropical agroforests are diverse systems where several predator groups
shape animal communities and plant–arthropod interactions. Ants, birds and
bats in particular can reduce herbivore numbers and thereby increase crop
yield. However, the relative importance of these groups, whether they
interact, and how this interaction is affected by management and landscape
context, is poorly understood. We jointly manipulated access of ants,
birds and bats in Indonesian smallholder cacao agroforestry across
gradients of shade and distance to natural forest. We quantified arthropod
abundance, pest damage and yield. In control treatments, yield was highest
under 30–40% canopy cover. Ant exclusion strongly reduced yield (from 600
to 300 kg ha−1 year−1) at 15% canopy cover. Bird exclusion impaired yield
(from 400 to 250 kg ha−1 year−1) at 60% and enhanced yield (from 600 to
900 kg ha−1 year−1) at 15% canopy cover, while bats had no effect. Yield
increased with forest proximity, a pattern not related to predator access.
No interactive effects among predator exclusions on yield, pest damage and
arthropod communities were found. Ant exclusion increased numbers of
herbivores below 30% canopy cover, without reducing spider abundances.
Bird exclusion reduced herbivore and increased spider abundances.
Synthesis and applications. Using exclusion studies, we estimated that
ants and birds cause cacao yield to vary between 100 to 800 kg ha−1
year−1, depending on shade-tree management. In all but the most shaded
agroforests, ants were pivotal in supporting yields. Yields under
low-canopy cover were strongly dependent on access by predator groups,
with birds reducing rather than increasing yield. Hence, cacao farmers
should refrain from disturbing ant communities and maintain 30–40%
shade-tree canopy cover not only for ecophysiological reasons but also to
buffer variability in predator communities.