Crown fires occur when large, high-intensity fires take out all of the above-ground living material. Chaparral and many forest types, like the lodgepole pine forests in Yellowstone, are characterized by high-intensity crown fires where most, if not all the vegetation is consumed. This is a perfectly natural event.
Often described as a "moonscape," areas like this burned during the 2009 Station Fire, although definitely appearing desolate are perfectly natural post-fire landscapes. Within a few months, this area was exploding with new life. High-intensity fire is exactly what chaparral is adapted to survive.
Mixed-severity fire that characterized the 2013 Rim Fire on the Stanislaus National Forest. Large and small patches of unburned, scorched, and completely burned trees.
2) MIXED-SEVERITY FIRES
Mixed-severity fires, found in certain types of forests, burn in patches. In some places, the fire creeps along the ground, only burning the understory while leaving larger trees unharmed. In other places, the flames burn up into the crown of the trees, burning all of the above-ground living material. This type of fire is typically found in drier forests like ponderosa pine in the American Southwest and some mixed conifer forests in the western Sierra Nevada.
The important thing to remember about forests characterized by mixed-severity fire is that the size of the burn patches varies depending on weather and climatic conditions. Long-term drought, low humidity, and wind can create conditions where a huge, high-severity fire "patch" can take out hundreds of acres of trees, burning through both dense and sparsely forested areas.
Each Ecosystem has its Own Special Relationship to Fire
To find out more about each fire type, please click on description above.
Fire as a Disruptive Force
Is fire a good thing for chaparral as many people claim? The answer is no because such a statement is overly simplistic and based on misunderstandings about the role of fire in the chaparral ecosystem.
If you have a home, you likely have fire insurance. Why? It certainly doesn't mean fire is good for your home and that you should be burned out every 30 years. You have fire insurance so you and your family can rebuild after the fire. It's the same for chaparral. Many chaparral species have adaptations that allow them to create a new, pyrogenic habitat and carry on. They don't "need" to burn, but have the adaptive insurance to survive in the event a fire occurs.
Since fire has been a recurring, although infrequent event for millions of years in the chaparral, only those species that have adaptations allowing them carry on after the flames will persist. How do they do this? Many chaparral plant species take advantage of some fire cue or post-fire environmental conditionfor maximal reproductive success.
Before humans arrived on the scene, the fire return interval for chaparral was on the order of 30 to 150 years or more. But humans have caused fires to increase dramatically, especially in southern California. With climate change, the southern California fire pattern is heading north.
So, it's better to think of chaparral plants as not "fire-adapted," but rather adapted to a particular fire regime or pattern. Change the pattern (season of burn, frequency, intensity, etc.) and chaparral's continued existence is threatened.
Learning About Fire
Fire ecology is an amazing, fun subject to explore. Post fire pyrogenic habitats offer some of the most biodiverse environments on earth. From fire-cued seed germination to the resiliency of native species, there are endless opportunities to learn about the wonders of life.
Unfortunately, there are also a tremendous amount of misconceptions about fire that many of us pass along because we have heard them so many times. To create a new generation of thinkers who embrace the challenge of questioning authority and understanding the world through a logical, fact-based approach, we have designed an innovative Chaparral Naturalist program that we invite you to consider.