Wildland-Urban Interface Areas Have Increased by More Than 35% in the Past Two Decades, Study Finds

Over the course of the last several decades, people seeking to move out of populated areas have been increasingly building homes in neighboring wildlands.

Wildland-urban interface (WUI) — places where human development meets undeveloped natural areas like grasslands, deserts or forests — grew by 35.6 percent from 2000 to 2020, according to new research led by three environmental scientists from the Institute of Geographic Sciences and Natural Resources Research at the Chinese Academy of Sciences.

The surge in WUI areas means more contact between people and wildlife, such as coyotes and bears, reported Phys.org. It has also resulted in an increasing number of homes being destroyed by smaller, local wildfires.

“Rapidly increasing human-nature interactions exacerbate the risk of exposure to wildfires for human society. The wildland-urban interface (WUI) represents the nexus of human-nature interactions, where the risk of exposure to natural hazards such as wildfire is most pronounced,” the authors of the paper wrote. “The increase in WUI was primarily driven by the unprecedented expansion of global urbanization, contributing an additional 589,914 square kilometer[s] of WUI. In addition, the number of small fires occurring in WUI areas has increased substantially since 2010. These findings underscore the rising wildfire risk to human society and highlight the urgency of implementing tailored fire management strategies in WUI areas.”

The research team — which included a colleague from the Ministry of Education in China — used satellite analysis to find evidence of how much WUI areas had expanded over the course of 20 years. The team observed the increase in WUI areas around the world using global satellite data from 2000, 2010 and 2020.

The researchers noted that there had been a roughly 85 percent increase from 2010 to 2020, which suggested the pace of WUI was growing. They found the highest growth rates in Nigeria, eastern China and several regions of the United States.

The team analyzed the data to find out if WUI area growth had led to an increase in wildfires. They discovered that the low-intensity fire rate had risen inside WUI areas, but that high-intensity fires were more likely to happen outside these areas.

“Considering the current large wildfire scenario we are in, an increase in the wildland-urban interface increases vulnerability to large fires. These areas are highly exposed to the impact of large fires, as they are surrounded by forest areas that are often unmanaged and without barriers or minimum safety distances,” said Adrián Regos Sanz, a postdoctoral researcher with the Biological Mission of Galicia, as Science Media Centre reported.

The research team concluded that the results of their study could help wildfire officials manage risk.

Sanz said the study “is a wake-up call for current (or past) spatial planning and the current trend towards greater exposure and vulnerability to future wildfires in urban areas. Consideration should be given to how this wildland-urban interface can be reduced, and the perimeters of rural and urban areas should be secured with buffer zones or more open habitats that break the fuel (vegetation) continuum and provide opportunities for fire suppression in these areas.”

The study, “Global expansion of wildland-urban interface intensifies human exposure to wildfire risk in the 21st century,” was published in the journal Science Advances.