Forest Fires Actually Can Be Good for Surviving Trees - Science in the News

Photo Credit: U.S. Department of Agriculture

By Amber Bennett

You probably think that fires are bad for forests. However, a recent study shows that the opposite can be true.

Hydrologists with the National Park Service at Yosemite National Park have been studying evapotranspiration. This is the process of plants releasing extra water into the air as vapor through tiny holes in their leaves.

Over the course of 18 years, the scientists measured the water-vapor release using sensors in two river basins in California. Then, they compared the amount of vapor released from burned areas of the forest to that of unburned areas. 

The Yosemite study looked at areas where forest fires that reduced the amount of young trees and underbrush by 40-50 percent. In these areas, roughly 17 billion gallons (77 billion liters) of water was saved from being lost to the air as vapor. That's a huge water savings!

So, How Do Fires Help Forests?

Without human intervention, a wildfire will go through a forest every couple of decades. This process is actually beneficial for the forests because it removes underbrush and young trees, leaving fewer plants to suck up water from the soil. Then, there's more water for the remaining trees — and downstream in reservoirs and rivers. With less competition, the surviving trees grow stronger and healthier.

Because of the benefits, some forest managers use controlled burns to remove excess underbrush and young trees. Others remove the extra "understory" trees and brush with logging in an effort to prevent unplanned fires.

Conclusion

Although the study's results are interesting, this process might not work as well in other climates. The remaining plants after a fire in drier climates might suck up all the water, leaving no extra to go downstream. 

Want to learn more? Check out this article in Science News for Students.