© 2018 by Janelle E. Letzen, PhD

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Science Snack

Disturbances like wildfires are a natural part of terrestrial ecosystems. Some plants and animals actually rely on them. Lodgepole Pine seeds only open with the heat of a fire, and “firehawks” in Australia have been observed intentionally spreading fire by carrying burning sticks in their beaks to make prey animals flee into the open, making them easier to catch.

But science indicates that wildfire frequency and intensity are exacerbated by human activities and human-driven climate change. In the Mexican state of Nuevo Leon where @becky.outside is studying her Masters, 74% of the forest fires from 2000 to 2017 were started by either smokers, campfires, burning trash or power lines. Wildfires also become more intense due to drought and spread more quickly in urban areas due to the density of human structures.

Fire, from a forest fire to a campfire, is simply a chemical reaction known as combustion.

wildfires sushi science

Oxygen gas in the presence of a hydrocarbon fuel source will ignite easily and begin to combust, or burn. Hydrocarbon sources are everywhere, all you need is hydrogen bound to carbon. Two excellent sources are forests and human structures.

Combustion reactions create carbon dioxide, water, and energy, usually in the form of heat and light. It might seem odd that combustion reactions create water, but because they are also producing heat (something we refer to as an exothermic reaction in chemistry) that water quickly evaporates into a gas.

You also observe salt, sodium chloride, burning in most fires. Sodium atoms are excited by the energy produced during a combustion reaction. Eventually they will lose that energy by emitting light, and that light is orange, which is why fires burn orange.

Ecosystems are adapted to a certain pattern of disturbance, but when disturbances become more frequent and intense it becomes difficult for an ecosystem to recover to its mature state, threatening the survival of the species within the ecosystem.

With climate change already affecting forest fires worldwide, we need to be more careful than ever at maintaining healthy ecosystems for animals and people. Only you can prevent forest fires!


McCreary, J. K., Truica, L. S., Friesen, B., Yao, Y., Olson, D. M., Kovalchuk, I., ... & Metz, G. A. (2016). Altered brain morphology and functional connectivity reflect a vulnerable affective state after cumulative multigenerational stress in rats. Neuroscience, 330, 79-89.