The study shows that large stands of aspen are more frequently found along the edges of wildfires than within heavily burned areas, indicating that these forests can act as natural barriers during wildfire events.

The findings could influence future tree planting strategies around communities, critical infrastructure and commercial forests.

Researchers also developed a new remote-sensing mapping tool capable of producing near-real-time wildfire disturbance maps. The technology could improve wildfire monitoring while supporting more informed forest management decisions across Canada.

Aspen trees reduce wildfire severity

The research provides the strongest national-scale evidence to date that aspen trees play an important role in limiting wildfire intensity.

Although individual aspen trees are relatively vulnerable to fire because of characteristics such as their thin bark, the study found that extensive aspen stands behave very differently. Larger patches were consistently associated with lower fire severity and appeared to slow the advance of wildfires.

By analysing fires across Canada, the team discovered that aspen forests occurred far more often around wildfire perimeters than inside the areas most heavily affected by burning.

This pattern suggests that dense aspen stands can interrupt fire progression, reducing both the likelihood of severe burning and the distance fires can spread.

The researchers believe this makes aspen a valuable species for planting around populated areas and critical infrastructure where reducing wildfire risk is becoming increasingly important.

Large-scale data reveals new patterns

The study was made possible through newly available satellite data and advanced remote-sensing techniques.

Researchers combined imagery from NASA’s Landsat programme and the European Space Agency’s Sentinel-2 satellites to develop an algorithm capable of generating near-real-time maps of forest disturbances, including wildfires.

These maps were then integrated with recently released Canadian Forest Service datasets identifying dominant tree species across the country. This allowed the team to examine how wildfire behaviour differed depending on forest composition at an unprecedented national scale.

The new analytical approach enabled researchers to identify relationships between wildfire severity and forest type that had previously been difficult to observe.

Findings remain consistent during severe fire conditions

The team also investigated whether seasonal conditions influenced how effectively aspen forests slowed wildfires.

Researchers expected that spring fires might burn more intensely through aspen stands because trees have not yet developed their leaves and are typically drier during this period.

However, the analysis found no meaningful relationship between the season of a wildfire and either fire severity or the amount of aspen present around fire boundaries.

The results also remained consistent during Canada’s record-breaking 2023 wildfire season, when extreme fire weather created unusually challenging conditions.

According to the study, the ability of large aspen stands to limit fire progression appeared stable even during periods of elevated wildfire activity.

Implications for forest fire management

The findings could have important implications for future forest fire management strategies.

Planting more aspen trees near communities, transport networks and other critical infrastructure could provide an additional layer of wildfire protection while complementing existing fire prevention measures.

The research may also influence commercial forestry practices. In some managed forests, aspen is removed to encourage the growth of more commercially valuable conifer species. However, retaining mixed forests that include aspen could improve wildfire resilience while also supporting biodiversity.

The researchers also expect their mapping technology to support operational wildfire response. The Canadian Forest Service is considering using the new remote-sensing system alongside its existing daily fire maps, providing faster and more detailed information to assist wildfire monitoring and decision-making.