Wildfire Smoke: How Does It Affect Your Trees?

As arborists, the effect of the air quality from the wildfires in Canada has been a topic at the forefront of our minds, as I’m sure it has been for most of you. How might the smoke from the blaze affect the growth of our trees? 

Photosynthesis And Carbon

The rate of photosynthesis in plants is limited by several factors. These factors include available light, temperature, carbon dioxide (CO2), and soil moisture.


Smoke’s basic chemical makeup contains carbon monoxide (CO), carbon dioxide (CO2), and particulate matter (PM or soot). Plant physiologists have long known that plant growth increases as available atmospheric CO2 increases.

CO2 Levels Graph

Trees are amazing carbon fixers. All parts of trees that we admire are built from carbon-based molecules taken from CO2 in the air. Trees up North are releasing a lot of carbon right now, much will be taken up by the trees downwind to help them grow.

Effect of change in CO2 levels graph


Particulate matter from smoke causes light to refract and become diffuse. Diffused light can largely be beneficial to plants because it allows light to be more evenly distributed throughout the canopy. 

However, if there are too many particulates in the atmosphere, light can become limited which will decrease photosynthesis.

For more information on light diffusion, take a look at this study conducted by AGU in 2020.

Forest fires are not quite welcome, and smoky skies are definitely not, but it may help to know that living trees in Ohio may be gaining growth from all of the extra carbon.

Photos by Ahlum & Arbor Sales Arborist José Fernández.