How Do Wildfires Impact Plants?

Once ignited, wildfires can spread rapidly and cause significant destruction across large areas of land, consuming thousands of acres. This can have a wide range of effects on trees and other plants in affected areas, according to one NC State expert. 

“Wildfires can be beneficial or detrimental to landscapes. The outcome varies from fire to fire because it depends on their intensity, frequency and the ecosystem involved,” said Robert Scheller, a professor of forestry and environmental resources at the College of Natural Resources, who studies fire ecology.

For example, wildfires can release nutrients back into the soil. When vegetation burns, the trapped nutrients within the plants are released back into the soil as ash. That ash is rich in nitrogen and other nutrients that act as natural fertilizers for new plant growth. 

On the other hand, wildfires can allow invasive plants to establish and spread, especially in areas where native plants are not adapted to fire. Many invasive plants have adaptations that allow them to quickly grow in the soil conditions left behind by high-intensity wildfires; essentially, they outcompete native plants. 

Frequent, low-intensity wildfires can reduce understory vegetation, “clearing” the forest floor and creating space for new growth to emerge later on, according to Scheller. “A frequent fire regime can reduce forest density and increase the abundance and diversity of plants in the understory,” he said.

Scheller added that frequent, low-intensity wildfires are especially important for maintaining the structure of savannas and open woodlands. By burning away dense undergrowth, these fires prevent the dominance of trees and promote the growth of grasses and forbs. 

High-intensity wildfires, on the other hand, not only reduce understory density but can also burn the crowns of trees, essentially “thinning” the tree canopy. This allows more sunlight to hit the ground, promoting new growth. This can also help reduce the prevalence of pests and pathogens in forests. 

“Pests and pathogens prefer a dense forest of all the same species,” Scheller said. 

Scheller added that high-intensity wildfires can also shift species dominance. After a fire, landscapes are often open with less competition. Some plants have evolved adaptations like the ability to sprout quickly after a fire, giving them a competitive advantage in post-fire environments.

High-intensity wildfires can also degrade surface soils, making them less capable of supporting new growth, according to Scheller. The heat of a severe wildfire can reach temperatures high enough to sterilize soil by killing bacteria, fungi and other soil microbes that are crucial for nutrient cycling and soil structure.

Additionally, high-intensity wildfires can also contribute to erosion by destroying plants which normally hold soil in place, leaving the exposed soil susceptible to being washed away. The loss of soil can ultimately reduce the fertility and productivity of affected areas.

If high-intensity wildfires occur in rapid succession, they can kill most of the existing vegetation, even those that have adaptations such as deep roots or thick bark, leaving the landscape open for grasses to outcompete trees and other plants that are severely damaged. This can actually “flip” ecosystems from forests to grasslands or brush fields, according to Scheller. 

“Grasses and other wind-dispersed plants can spread their seeds very long distances, allowing them to take advantage of the bare ground and lack of competition following a fire,” Scheller said.

Ultimately, no matter the frequency or intensity, Scheller said there will almost always be some kind of plant capable of regrowing after a wildfire if there’s enough moisture in the soil. In fact, some plants require fire to regenerate.  

Pine trees with serotinous cones, for example, require fire to reproduce. The cones are sealed with a strong resin that protects the seeds within. Fire melts the resin, allowing the cones to open up and release seeds on the ground.

Wildfires are becoming increasingly common within forests and shrublands as climate change accelerates, according to Scheller. In January 2025, for example, multiple wildfires erupted and engulfed over 40,000 acres throughout the Los Angeles area, fueled by drought conditions and strong winds.