May 8, 2013 Three Different Types of Forest Fires
Fire is an integral part of western forests and all forest types throughout North America, Australia and elsewhere have evolved and adapted to fire.
Three types of forest fires occur.
When treetops burn it is called a crown fire and its lethal for most trees. In California oaks and big cone Douglas-fir, for example can regenerate new leaves after being scorched.
Other trees across the West have developed a strategy to take advantage of crown fires. In the Rocky Mountains and elsewhere, for instance, lodgepole pine (except in California and along the Pacific coast) cones open after the heat of a crown fire, releasing millions of seeds which quickly recolonate the land. Lodgepole pine forests are usually of the same age, because all the trees started to grow at the same time following a fire. If, however, fire is suppressed in lodegpole pine forests then conditions are created for another agent of change, the mountain pine bark beetle. It enters the ecosystem and ultimately creates new forests.
Surface fires burn from the top of the forest floor to about 12 feet above ground. Certain trees like Douglas-fir, ponderosa pine, and Sequoia’s have adapted to tolerate this type of fire. They hold their branches high in the crown so that the flames cannot ignite the foliage. And they have at least one-foot thick bark, which helps protect the trunks of these trees from the heat of fast moving surface fires. If you look closely at old living Douglas-fir, ponderosa pine or western larch trees you will notice that they have blackened bark or fire scars indicating the past occurrence of surface fires.
The ponderosa pine ecosystems may naturally experience surface fires that occur every 15 to 20 years. A Smokey Bear policy of stopping all fires across the West for about 95 years has dramatically changed the structure of these forests. There are now hundreds of trees and thousands of saplings per acre instead of dozen or so big trees surrounded by a sea of native grasses. The mature, big old ponderosa’s are well adapted to surface fires. Now, however, when fire gets into unnaturally overcrowded ponderosa forests, smaller trees act as a ladder for surface fires enter the crown and become crown fires. Ponderosa have not evolved nor adapted to contend with crown fires and so the entire forested ecosystem burns. It then takes decades for this ecosystem to naturally recover because ponderosa seeds becomes limited. And in some cases the ponderosa forests may not return as parts of the West are becoming to dry for these forests to re-establish.
The third type of forest fire is a ground fire. When the forest floor and all its decomposing wood, fauna, bacteria and fungi become alight, it’s a disaster. It can burn for months under a snow pack and flare up again in the springtime. This is a common problem in higher elevation forests and throughout British Columbia and Alaska. Ground fires scorch the forest floor and deplete soil nutrients that take decades, and in some cases a century, to accumulate.
One of the major concerns about climate change are droughts. Droughts promote the drying out of the forest floors which in turn makes them more prone to ground fires.
Fire must be thought of as one of Mother Nature’s agents of change. And wild forests like all wild ecosystems are constantly experiencing change. Clearly, it is not fiscally prudent to continue to suppress all wildfires yet many communities are at risk like Los Angeles, for instance. They must be fireproofed by manually thinning surrounding forests. This can be achieved by utilizing the labor force of prison inmates, which incidentally are currently used on the fire lines in California. During the winter months prison inmates could thin-out, for a fraction of the tax-payers cost of professional fallers, the over stocked forests surrounding millions of homes across the West.
Text © by Dr Reese Halter 2014. All rights reserved.
Tags: Alaska, Australian Conservation Foundation, Avaaz, california, California wildfires, climate change, Colorado wildfires, crown fires, Defenders of Wildlife, Douglas-fir, Dr Reese Halter, drought, Ducks Unlimited, ellen degeneres, environment, Environmental Defense Fund, firestorms, global warming, ground fires, Jacque Cousteau, John Denver, lodgepole pine, Los Angeles, mountain pine beetles, Nature Conservancy, New Mexico wildfires, Oprah, ponderosa, Rocky Mountains, science, Sequoia, Steve Irwin, surface fires, water, wild fires, world wildlife Fund