Revealing the Widespread Mosaic of Shifting Cultivation Across the Tropics
By combining deep learning with high-resolution satellite imagery, this study reveals that shifting cultivation remains a widespread and persistent agricultural system across the tropics, covering approximately 212 million hectares in 2020 with distinct regional distributions and strong associations with plantation proximity.
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
For centuries, a specific way of farming has shaped the landscapes of the tropics, supporting millions of people from the rainforests of the Congo to the hills of Southeast Asia. This practice, often called shifting cultivation or "slash and burn," involves clearing a patch of forest, burning the vegetation to release nutrients into the soil, and planting crops for a few years. Once the soil's fertility drops, the farmers move to a new patch, leaving the old one to rest and grow back into a forest. This cycle creates a living mosaic of fields, young forests, and mature trees. For a long time, outside observers viewed this system as a dying relic, a low-productivity method destined to vanish as the world modernized. Many believed that as markets grew and populations increased, these farmers would inevitably switch to permanent, intensive farming, leaving the old ways behind. However, this assumption has left a massive gap in our understanding of the global environment. Without knowing exactly where this farming still happens, how much land it covers, and how it interacts with modern plantations, it is impossible to accurately measure carbon storage, track deforestation, or design policies that protect both forests and the people who depend on them.
A team of researchers has now filled this gap by creating the most detailed global map of shifting cultivation ever produced. By combining high-resolution satellite images with advanced computer learning, they have tracked down this elusive agricultural system across the tropics, revealing that it is far more widespread and persistent than previously thought. The study, which covers 76 countries, estimates that shifting cultivation currently covers an area of 211.7 million hectares. To put this in perspective, that is a vast expanse of land, larger than many continents, where this ancient cycle of planting and resting continues to define the landscape. The researchers found that this system is not fading away; instead, it remains a dominant form of agriculture in many regions, particularly in Africa, where it covers more than half of the agricultural land in countries like Liberia and the Democratic Republic of the Congo.
The power of this new map lies in how the researchers found the farms. Traditional methods of mapping land use often rely on watching a single spot over many years to see when trees disappear and reappear. This approach struggles in the tropics because clouds often hide the ground, and the patterns of shifting cultivation are complex. Instead, the team treated the landscape like a puzzle of shapes. They trained a computer to recognize the unique visual signature of shifting cultivation: a patchwork of small, irregular fields mixed with regrowing trees and forest remnants. Using images from a constellation of small satellites that can see the ground in great detail, the computer learned to spot this specific mosaic pattern instantly, even from a single snapshot. This allowed the team to map the entire tropics at a resolution where individual fields can be distinguished, a level of detail that was previously impossible on a global scale.
The results challenge the old story that shifting cultivation is only a hillside practice for remote communities. The map shows that these farms are often located on gentle, flat terrain, frequently sitting right next to modern industrial plantations. In Asia and the Americas, nearly all shifting cultivation areas are found within a short distance of large-scale plantations growing crops like oil palm, rubber, or cocoa. In Africa, the pattern is slightly different, with these farms often bordering permanent crop fields or existing in savanna woodlands rather than deep rainforests. This proximity suggests that the transition from traditional farming to industrial agriculture is not a clean break but a messy, overlapping process. Farmers are not just moving away from the forest; they are often living and working in the same landscape as massive commercial operations, creating a complex mix of land uses that traditional maps missed.
The study also sheds light on the environmental impact of these systems. By cross-referencing their map with data on tree loss, the researchers found that the intensity of clearing varies greatly. In some areas, the cycle is stable, with fields being cleared and then allowed to recover, maintaining a balance of trees and crops. In other hotspots, particularly in parts of West Africa and the Democratic Republic of the Congo, the clearing is much more intense, with a higher proportion of trees being lost in recent years. The data suggests that the fate of these forests depends heavily on local conditions. In countries with higher levels of economic development and better infrastructure, the reliance on shifting cultivation tends to decline, often giving way to more permanent tree-based systems like plantations. However, the researchers caution that this shift does not automatically mean better environmental outcomes. If the new permanent systems replace diverse, tree-rich fallows with monocultures, or if the land is simply cleared for pasture, the result can be a net loss of carbon and biodiversity.
Perhaps most importantly, this map provides a foundation for better decision-making. For decades, shifting cultivation has been invisible in global statistics, often lumped together with general deforestation or ignored entirely. By making this system visible, the study allows scientists and policymakers to see exactly where these landscapes exist and how they are changing. It reveals that shifting cultivation is not a monolithic problem but a diverse set of practices that interact differently with local economies and ecosystems. In some places, it is a resilient strategy that supports local communities and maintains forest cover. In others, it is under pressure from population growth and market forces, leading to shorter rest periods and more frequent burning. The map does not solve these complex issues, but it offers a clear, factual starting point. It shows that the future of the tropics' forests depends not on erasing these traditional systems, but on understanding their specific roles and supporting the transitions that protect both the land and the people who work it.
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