A post in Worldchanging called Climate Action: Burning Forests to Avoid Megafires by Yale Environment 360 begins:
"Prescribed burns in the forests of the western U.S. will prevent larger wildfires and significantly cut the nation’s carbon footprint, according to a new study."
In a comment on that post @new_illuminati wrote:
"It's been a common practice here to burn forest in the way you describe but the result has been decimation of diversity and destruction of soils in many instances."
The comment troubled me because I believe that prescribed burns are very often the right thing to do to protect nearby home owners and save forests. I worry that, without the whole story, concerned citizens fearing what may happen to their neighborhood and their homes will block prescribed burns.
A prescribed burn in a forest near you raises the short term risk of fire damage, but it generally reduces the long term risk to your property, the surrounding forest and your life. In most cases, after some frank conversation concerning the short term and long term risks, we should be brave enough to accept the short term risk to increase our long term safety. We don't need the fact that the prescribed burns are necessary to restore the forest to a healthy condition or needed to fight global warming to decide that prescribed burns are worth the risk to property and forest to increase the safety and protect the property of the immediate community. Here is why:
There are two main kinds of forest fires, ground fires and canopy fires. In a ground fire the burn stays down near the ground, burning underbrush and smaller trees. It leaves the soil in good condition. Canopy fires burn the entire forest including the tops of big trees. They burn so hot that they sterilize everything both above the ground and down perhaps a foot into the soil.
Canopy fires also send out balls of superheated gasses that can jump half a mile as a cloud of smoke and then burst into flame when they get to oxygen. These fireballs ignite new patches of forest. They can trap fire fighters between two walls of flame.
When the fuel load is high and the weather is supporting it, nothing in the path of a canopy fire can be saved except by running away or a change in the weather. There must be a better way to manage our forests than to set up the conditions for canopy fires.
In many areas of the West, Native Americans managed the forest by setting frequent ground fires. This cleared out underbrush and many of the small trees, making it easier to hunt. It also created healthy forests.
As the glaciers retreated trees and people moved in at more or less the same time. Thus many North American forests co-evolved with people who were setting fires in them from the beginning. People setting fires are thus as much a natural part of many Western ecosystems as any other creature. We have just forgotten how to perform our role in the ecosystem correctly.
The common alternative to prescribed burning is to suppress all fire. This allows fuel loads to build up to the point where catastrophic canopy fires become almost inevitable. Compared to that danger, controlled burns in the right weather are far better than waiting for summer lightning to ignite same patch of forest during a dry period.
In most of the last hundred years, the Forest Service, and here my family deserves some of the blame, has done its best to suppress all forest fires. The results include "wilderness" ecologies quite different and far less healthy than those that were present when Europeans came to North America. The healthy ecosystems that greeted the European settlers had a park-like forest structure with abundant wildlife and open spaces in which to hunt.
But that was then. Now we face a difficult situation in many Western forests for two reasons.
- Clear cutting years ago created a race between large numbers of skinny, even-aged trees, all struggling for water and sunlight. Sick overcrowded trees are a prescription for canopy fire.
- Aggressive fire suppression has allowed fuels to build up in the understory as well as aloft.
Many forests throughout the West are ready to burn catastrophically. Firefighting's share of the Forest Service's budget has soared from 20% to 50%. Still we are not prepared. As a result, he Forest Services fire strategy is changing. They will fight fewer unwinnable battles and instead retreat to fight in a time and place where the fire is less strong. They will put more attention of preventing catastrophic fires and less on fighting them.
To prevent catastrophic canopy fires, overcrowded forests with excessive understory fuel loads need to be thinned. The understory needs to be cleared out. In theory this might be done by selective cutting of the smaller and less healthy trees plus a huge number Civil Conservation Core teams to clear the underbrush. Goats might help eat what is left. But in most cases there is not enough money for such exotic solutions.
Before the 2003 fires in the San Bernardino mountains, we were working to prepare the community to rebuild after them. I remember retirees being told to thin their trees and protesting that on a fixed income they could not afford to do so. Even the Forest Service was caught short. As I recall, when the Forest Supervisor estimated he needed a fuels reduction budget of well over $200 million, the Washington Office gave him about 1% of that. In most cases carefully setting fires in the right places at the right times is the only cost effective solution.
Prescribed burning is not easy in forests that have gone too long without fire. It is even harder when, like the San Bernardino mountains, people have built houses in and near the forests. Occasionally prescribed burns will get out of control and destroy property. But what is the alternative?
Doing nothing will result in the loss of more houses, more forest and more fire fighters. Prescribed burns are a percentage game, a fact that will give little comfort to the homeowner whose house is lost in a prescribed burn that gets out of control. However, the policy of using frequent fires timed as best we can is a better bet for everyone than waiting for a big fire in the dry season. That way lies disaster. So we set fires to keep ourselves safe. Bizarre, but perhaps the only sensible thing to do.