Every year, Amazonian rivers spill over their banks and flood the forests around them for months. These wetlands cover around 30% of the Brazilian Amazon and are often home to riverine families, who live in adapted homes built on stilts. They fish and plant crops with the natural ebb and flow of the rivers.
But a new study has found that more than 6% of the total area of Amazon floodplain forests and other wetland areas has been cleared over the last 40 years. Nearly a third of that destruction occurred between 2015 and 2024.
“When we think about 6%, we may get the impression that it’s small, but the converted area is basically the size of Belgium,” lead author Guilherme Lobo, a researcher at the State University of Campinas in Brazil, told Mongabay by phone.
Researchers compared wetland clearing across 13 types of land designations and found huge differences.
Public land not yet assigned by the government to any specific use had the largest share of human-converted wetland: a median of nearly 14% had been deforested.
According to Lobo, people burn these lands to show they’re in use, hoping to claim a land title later. According to a 2026 study by Imazon, a Brazil-based research institute, federal and state land laws create incentives for such land-grabbing practices, locally called grilagem. Undesignated public land is routinely granted to the people who clear it, with deforestation used as proof of the productive use of the land to justify the land title claim.
Military-controlled areas are the least deforested wetland areas, the report found, with land conversion there under 0.01%.
Indigenous lands, whether formally recognized or not, also had very low rates of wetland conversion. In formally recognized Indigenous territories, land conversion was 0.2%, while in Indigenous lands still awaiting demarcation, the figure was 0.3%.
“In other words, those people already lived there and already protected it. It was a matter of formalization,” Lobo said. Other strictly protected areas also had very low wetland conversion rates, under 0.3%.
Government agrarian reform settlements, plots of land given to farming families, recorded the fastest yearly clearing. Within five years of being created, settlements cleared 1.4% of their wetlands, compared to 0.9% before settlement. After 15 years, 24% of wetlands with these settlements were converted for human uses, up from 8.5% before settlement.
According to the study, these settlement programs require their occupants, typically smallholders, to put land to productive use, while offering little environmental monitoring or support for other types of livelihoods.
Land designed for sustainable agrarian reform settlements, where families hold land collectively and harvest forest products, also saw wetland conversion, but more gradually, from 2.4% to about 3.5% over the same time frame.
“The problem is in the design,” Lobo said. “What separates the categories that conserve from those that don’t isn’t only having an owner, it’s having rules.”
Banner image: Seasonally flooded Igapó forest near Manaus, Brazil. Image courtesy of Alexey Yakovlev via Flickr (CC BY-SA 2.0).
