"Trees create a microclimate and lower stress underneath their canopy"
Voices on climate
Stéphane Saj is an agroecologist and systems researcher at FiBL in Switzerland. For over fifteen years, he has studied tropical agroforestry systems, focusing on cacao production, biodiversity, crop performance and climate resilience. Since 2023, he has coordinated long-term research within SysCom Bolivia, working with farmers and partners to better understand how agricultural systems can achieve sustainability.
Climate change is often described through global averages and future scenarios. But what does it mean in a cacao field, and can agroforestry help farmers cope with increasing climatic stress? These questions have guided our research in Alto Beni, Bolivia, where FiBL has operated a long-term cacao systems comparison trial since 2008. Located between the Amazon lowlands and Andean foothills, the region is highly sensitive to climatic variability.
The experiment's strength lies in its duration: sixteen years of climate records combined with eight years of detailed microclimatic measurements within cacao systems allow us to assess real-world conditions rather than assumptions.
Climate change is already visible
Results from SysCom Bolivia show clear local evidence of climate change. Over the past fifteen years, maximum temperatures increased by about 1.7 °C, while annual rainfall declined by roughly 400 mm compared with 2008. Although year-to-year variation remains high, warmer years have become increasingly common, indicating that farmers are already facing different climatic conditions to those of fifteen years ago.
This is important because cacao is naturally a forest-understory species adapted to stable temperatures and high humidity. Therefore, rising temperatures increase physiological stress and atmospheric water demand.Alto Beni faces an additional challenge: occasional cold spells, known as surazos. Cacao trees must therefore cope with both gradual warming and sudden cold shocks.
Why trees matter
Our data show that compared with monocultures, agroforestry systems consistently create cooler local conditions during the hottest hours of the day. They also lower vapour pressure deficit (VPD), an important indicator of atmospheric drought stress, a factorincreasingly recognised as a major constraint for cacao production.
What is striking is the consistency of these effects. Across different years and weather conditions, tree-based systems repeatedly reduced exposure to heat and dryness, effectively buffering cacao from regional climate extremes.
Canopy cover matters most
One key finding was that canopy presence influenced microclimate far more than management intensity. Whether systems were managed organically or conventionally had little effect on temperature and humidity. In contrast, the presence of tree cover was found to strongly improved microclimatic conditions.
We also compared conventional agroforestry systems with highly diversified dynamic systems inspired from forest species succession. Despite major differences in structure and biodiversity, both created very similar thermal environments for cacao.
Adaptation, not a miracle solution
Trees clearly help by lowering temperatures, reducing atmospheric drought stress and creating more favourable conditions for cacao locally. These benefits are measurable and significant.
However, agroforestry does not stop climate change. Long-term warming trends remain visible beneath the canopy. Trees can reduce climatic stress but cannot fully offset regional changes in temperature and rainfall. They provide adaptation, not immunity to climate change.
Today, agroforestry systems typically reduce temperatures by one to two degrees and substantially lower drought stress. Yet as regional temperatures rise and extreme events become more frequent, the climatic baseline continues to shift. Agroforestry acts as a buffer, whose effectiveness will depend on climate evolution patterns, rather than as a permanent refuge.
For perennial crops such as cacao, this distinction is crucial. Plantations are established for decades, making it essential to understand not only how much agroforestry buffers stress today, but also how long it can maintain suitable growing conditions in the future.
Looking ahead
The next phase of our research will focus directly on crop responses. By linking long-term climate trends, field-level microclimates, flowering patterns and yields, we aim to understand how microclimatic buffering influences the long-term productivity and resilience of cacao systems.
Further information
Contact
Link
systems-comparison.fibl.org: SysCom website