July 6, 2012 Trees and Wildfires in West
Forest fires have been prevalent in the West since trees first colonized the land. Amazingly, trees have evolved to tolerate fire and some species cannot live without it.
There are three kinds of forest fires: A crown fire occurs in the treetops and is lethal for most but not all trees, while a surface fire occurs from the ground level to about 8 feet above the surface, and a number of tree species have adapted to tolerate these fires.
Finally, when the forest floor alights, that’s a ground fire. It’s the worst type of fire because it burns and destroys all the insects, fungus and bacteria that assist in decaying wood and regenerating soil. A ground fire can burn all winter under a snow pack and re-ignite in spring. That’s what often happens in British Columbia and Alaska.
Wildfires throughout the West and elsewhere are lightning-induced. In the Pacific northwest on the coast, huge stand-replacing fires appear about every 500 to 700 years, or longer. Coastal forests tend to have uneven ages of trees with patterns scientists call patches. Wind and root rot create different ages of trees in this forest.
Away from the coast, ponderosa pine forests have learned to tolerate surface fires, which naturally occur about every 15 to 20 years (or less). The ponderosa pines live in what is termed “an open forest” with about three dozen big, old, fat pines per acre surrounded by a sea of grass. (Just like the forest Red Riding-hood skipped through.) They too have thick (at least half a foot) bark and hold branches higher than 18 feet above the ground. In these drier ecosystems, surface fire is Nature’s broom, cleansing the forest floor.
Fire suppression over the past 80 years has dramatically changed the ponderosa forest. Now there are thousands of trees per acre. When fire re-enters, the smaller trees provide a ladder for fire to get up into the crowns of the old pines and all trees perish. (They are not able to regenerate once their crowns have been scorched.) Restoration becomes difficult because there are no old ponderosa left to provide a new seed source to regenerate the forest.
To avoid forests being wiped-out (in these stand replacing fires), ponderosa pine forests must be manually thinned . In their current overgrown condition they are now fire hazards potentially threatening thousands of communities. The big old ponderosa trees must be left standing during this thinning process. Forest scientists have clearly proven that this approach of restoration ecology works and can effectively rehabilitate these overstocked ponderosa forests.
Lodgepole pine, on the other hand, is a fire specialist. When lightning-induced fire occurs in this even-aged forest, vast tracks of land are consumed. To contend with fire, this tree has adapted a cone that remains viable and shut tight on the tree for up to 20 years. When fire occurs it melts the resin around the cone scales and millions of seed rain on the exposed forest floor, allowing lodgepole to very quickly recolonize the land.
When fire is deliberately prevented, as forest policies over the past 80 years have done, and in concert with climate change it creates opportunities for other agents of change to enter the forest. That’s exactly why billions of mountain pine beetles are now such an enormous destructive force in Western North America.
Right now there are conservatively 100 million dead standing pines in Western North America. They must be removed so they don’t provide kindling to fuel monster fire storms in the coming summer. Prison inmates could be used, at a fraction of the cost to the tax payers to assist in this massive forthcoming task.
Earth Dr Reese Halter is an award-winning Science Communicator: Voice for Ecology and distinguished conservation biologist. His latest books are The Insatiable Bark Beetle and The Incomparable Honeybee
Text © by Dr Reese Halter 2012. All rights reserved.