Bulletin Banner

Return to 3rd Quarter 2017 articles.

Article title

The title of this article is FIRE AND PLANTS.

One of the interesting areas of forest management is understanding how plants and fire function in relation to each other. Some of us were brought up in the “Smokey the Bear” tradition when forest fires were regarded as the ultimate evil. We saw horrific pictures of forests being burned up, and of what the forest looked like a week after the fire decimated the area. I do not ever recall seeing what the forest looked like five years after the fire, even if humans were not involved in planting new trees. The fact is that there are many ways fires can start naturally, but lightning is probably the main cause. Fire is not an evil thing, and there are designs in nature that require it.

Fire can allow sunlight to reach seedling plants so they can grow. A good example is the giant sequoia. Sequoias are shade-intolerant, and their seedlings cannot compete with vegetation that thrives in the shade. When a fire goes through a grove of giant sequoias, it burns up the shade-loving plants and opens the canopy so that the sequoia seedlings can get sunlight. Without fire, the sequoias would die out.

Even more sophisticated are plants that are fire or smoke activated. The cones of the lodgepole pine are sealed with a resin that can only be melted by the heat of a fire. The seeds are released during a fire, and thus a burned-over area is rapidly reseeded. Plants of this type are called “obligate seeders.” They contain a receptor protein which is activated by the growth hormone karrikin which is released by the fire.

In chaparral communities in Southern California, some plants have leaves coated in flammable oils that encourage an intense fire. The heat causes their fire-activated seeds to germinate, and recovery of the area happens rapidly. Some plants such as the ponderosa pine grow in such a way that rapidly-moving fires do no damage to their crown which is above the fire. These pines shed their lower branches as they mature.

All of this planning and design speaks of intelligence and purpose. This design prevents fire from making an area empty of vegetation and selects specially-designed plants that thrive under the conditions of forest fires. As science has come to understand this design, we have learned how to better protect our natural areas. Source: Fire Ecology Journal. Available on fireecology.net/

Picture credits:
© aorlemann. Image from BigStockPhoto.com