Efforts to preserve the Amazon rain forest, which supports immense biodiversity and locks away about 123 billion metric tons of climate-threatening carbon, are growing ever more urgent as the ecosystem’s destruction accelerates. Indigenous peoples have been trying to protect the region by patrolling their territorial boundaries for illegal activities, blocking dam construction, and more. But rapid deforestation continues.

A recent study shows that combining on-the-ground monitoring with satellite data and smartphone technology could help put the brakes on Amazon deforestation—and potentially that of forests elsewhere. The results were detailed in the Proceedings of the National Academy of Sciences USA.

Illegal logging, agriculture and coca cultivation particularly threaten the Amazon in the Peruvian Indigenous communities the study examined—and outsiders are often the culprits. The research team wondered if providing training for local people to use satellite-based “early deforestation alerts” could help.

The scientists collaborated with 76 Indigenous communities, 36 of which participated in using these alerts to watch over the forest. Three people from each of the latter communities received training to use an early-alert system on a smartphone app and to patrol forests and document damage.

Over the next two years these trained participants were paid to work as forest monitors and received monthly alerts via the app when satellite data indicated local forest losses. Monitors investigated alerts and patrolled for deforestation in other areas. They reported confirmed losses back to their communities, which decided whether to deal with the culprits on their own or inform state authorities.

The researchers analyzed the same forest-loss satellite data from the given time period in all 76 communities. They found the early-alert program reduced forest loss by 8.4 hectares in the first year—a 52 percent reduction compared with the average loss in the control communities, says study co-author Tara Slough, a political economist at New York University. “This reduction in deforestation was concentrated in communities facing the largest threat” of forest loss, she adds. “If one were to continue the program, targeting it to the communities facing the biggest threats should avert the most tree-cover loss.”

Results for the monitoring program were less striking in its second year, when forest loss was reduced by only 3.3 hectares compared with that in control communities. The researchers suggest a Peruvian government campaign against coca cultivation that year may have discouraged deforestation in both experimental and control communities’ territories, shrinking differences between the two groups in the pilot program.

Experts say this approach to tackling Amazonian deforestation—community monitoring combined with smartphone early alerts—looks promising. “Would this work in all communities that have high risk of deforestation? Given the results, it’s worth a try,” says Catherine Tucker, a forest governance researcher at the University of Florida, who was not involved in the study. But some communities may not have access to the resources needed for such a program, or their territories may hold valuable minerals or petroleum that would increase the risk of deforestation by outsiders despite monitoring efforts, Tucker notes.

Indigenous groups may continue the work they started in the pilot program. “We want to replicate this in other communities. In doing so, we are making a contribution to the world,” wrote Francisco Hernandez Cayetano, a community member involved in the research and president of the Federation of the Ticuna and Yaguas Communities of the Lower Amazon, in a translated statement to Scientific American. “We as Indigenous peoples ask the world for support.”