Beyond deforestation: spatial heterogeneity and supply-chain drivers of terrestrial and aquatic biodiversity footprints of Brazil’s soy
This study reveals that while Brazil's soy-related terrestrial biodiversity footprint has decreased due to reduced deforestation, its aquatic footprint has worsened due to synthetic fertilizer use, highlighting the need for biodiversity governance to address diverse supply-chain drivers and spatial heterogeneity beyond just deforestation.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
When we buy a bag of soybeans or a bottle of cooking oil, we rarely think about the journey that brought it to the shelf. Yet, every item on a supermarket shelf carries a hidden history of environmental change, stretching from the soil where it grew to the ship that carried it across the ocean. For decades, scientists and policymakers have focused heavily on one specific part of this story: deforestation. The logic was straightforward. If you stop cutting down forests to make room for farms, you save the animals and plants living there. This idea has driven major international agreements and corporate pledges to stop buying from areas where trees are being cleared. However, nature is complex, and the damage done to the natural world is not limited to the loss of trees. Pollution from fertilizers, changes in the climate, and the sheer act of farming on land that was once wild all contribute to the decline of biodiversity. Understanding the full picture requires looking beyond the trees to see how the entire supply chain, from the local farm to the global market, affects the living world.
A new study by researchers at the Universitat Politècnica de València and the Basque Centre for Climate Change takes a deep dive into this hidden complexity, focusing on the massive soy trade of Brazil. Over an eighteen-year period, from 2004 to 2022, the team traced the path of more than one hundred thousand distinct supply chains. They did not just look at how much soy was grown or where it was sold; they mapped the specific journey of every shipment, connecting the exact municipality where the crop was harvested to the port it left from and the country where it was finally consumed. By combining detailed trade records with maps of land use and agricultural practices, they calculated two types of "footprints" for the entire market. The first measures the loss of life on land, such as the disappearance of birds, mammals, and insects. The second measures the loss of life in water, caused by pollution and climate change affecting rivers, lakes, and oceans. Their goal was to see if the current focus on stopping deforestation was enough to protect biodiversity, or if other factors were driving a different kind of loss.
The results reveal a story that is far more nuanced than a simple narrative of saving forests. While the total amount of soy traded from Brazil grew by 144 percent during the study period, the impact on land-based biodiversity actually decreased by 23 percent. This improvement is largely due to successful efforts to reduce deforestation in areas where soy is grown for export to Europe, and a shift in where China, the largest buyer, sources its soy. China began buying more from regions that are less sensitive to habitat loss, such as the southern parts of Brazil, rather than the fragile rainforests of the north. Consequently, the amount of natural habitat destroyed per ton of soy has gone down. However, the story for water-based biodiversity is very different. The impact on aquatic life has steadily worsened, increasing by 146 percent over the same period. This rise is not driven by cutting down trees, but by the heavy use of synthetic fertilizers. As farmers apply more chemicals to boost yields, these substances run off into waterways, causing pollution that harms aquatic ecosystems. The study shows that while we have made progress in protecting forests, we have inadvertently allowed pollution to become a dominant driver of biodiversity loss.
The researchers also discovered that the impact of soy is not spread evenly across the map. The damage is highly concentrated in specific places and specific trade routes. Just five Brazilian states account for nearly 80 percent of the impact on water life, while a tiny fraction of the country's municipalities are responsible for almost half of the land-based loss. For instance, a few small towns in the state of Roraima, in the deep Amazon, have a disproportionately large footprint because they are converting pristine rainforest into farmland. In contrast, the southern states, where farming has been established for decades, show a much lower impact per ton of soy because the land transformation happened long ago. This spatial variation means that a policy that treats all soy as the same is ineffective. Buying soy from one region might save a forest, while buying from another might be driving pollution in a river system. The study highlights that the countries importing this soy also have distinct footprints. China and the European Union, which together with Brazil's domestic market consume the vast majority of the crop, are responsible for the bulk of the total impact. Yet, their specific impacts differ: the EU's imports are linked to higher rates of deforestation in sensitive biomes, while China's imports, though massive in volume, are linked to less sensitive areas, resulting in a lower impact per ton of land loss.
Perhaps the most surprising finding concerns the role of the companies that move this soy around the world. The study tracked the footprints of the major traders, identifying a handful of global giants that control nearly half of all exports. These companies act as gatekeepers, and their sourcing decisions directly determine which landscapes are affected. The research suggests that these traders have the power to influence production practices far beyond just the export route. If a trader decides to source only from municipalities that have not cleared new land, they can significantly reduce the land-based footprint. However, the study also notes that many traders source from areas with high pollution intensity, meaning that even if they stop deforestation, they may still be driving the worsening of aquatic biodiversity. The authors point out that current regulations, such as the European Union's new rules requiring companies to prove their products are deforestation-free, might miss this critical issue. By focusing solely on the absence of tree loss, these policies might fail to address the growing problem of chemical pollution, which is now the primary driver of biodiversity loss in the aquatic realm.
The study does not claim to have solved the problem of biodiversity loss, nor does it suggest that the current situation is hopeless. Instead, it offers a clearer map of where the pressure is coming from. It shows that the fight to protect nature cannot be won by looking at forests alone. The researchers argue that effective governance must account for the different drivers of loss, recognizing that pollution and climate change are now just as critical as habitat destruction. They emphasize that the solution requires looking at the specific details of where and how food is produced, rather than relying on broad averages. If a country or a company wants to truly reduce its impact, it must understand that buying from a region with low deforestation rates does not automatically mean it is buying a clean product. The path forward involves a more granular approach, one that traces the specific journey of every shipment and addresses the unique environmental pressures of each supply chain. Only by seeing the full picture, from the fertilizer in the soil to the ship on the ocean, can we hope to build supply chains that do not cost the natural world its future.
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