Prescribed burning is more than just igniting fuels

With more than 4,000 acres of land in the Lake Tahoe basin being burned by the U.S. Forest Service annually, prescribed burns have become an important part of keeping forests healthy.

On Thursday, I followed the Tallac Hotshots as well as Engines 41 and 42 from the U.S. Forest Service as they burned an eight acre parcel off Grass Lake Road in Christmas Valley.

Previous crews had created the burn piles in the spot about two years ago, though many piles in other areas can stay for three to four years in advance of a prescribed burn. The wood in the piles need to cure so it will burn cleaner and efficiently, leaving as little remnants behind as possible.

Since they never know when conditions will allow them to burn, they need to have piles ready to go at short notice. Piles may stay around longer than planned for the same reason, because conditions weren't good for a period of time to allow burning.

Once called "controlled burns," the Forest Service now follows a prescription in order for the operation to be successful, therefore they have changed the name of the events to "prescribed fires."

The burn prescription determines the environmental conditions necessary for meeting resource objectives in a safe, effective manner. Weather conditions are checked, and re-checked to determine humidity, wind direction, wind speed as well as other variable.

For South Lake Tahoe, the "fire boss" must get approval from the El Dorado County Air Management District. Smoke coming off the fire needs to get broken up and able to get out of the basin so the District will tell them how much they can burn.

There are environmental concerns as well.

"We need to know if we can put a fire on the landscape that will meet the requirements," said Dave Soldavini, the Engine 42 Captain for USFS.

Soldavini said the final plan for the burn started three days ago. Crews, fire trucks, equipment all need to be planned out, along with weather reports, surveying of the site and everything else needed to meet the expectations.

The prescription includes how the fire will be ignited and contained.

Controlling where the smoke will go is an important part of every prescribed burn. Before each burn, land managers (or, the Fire Boss) look carefully at what they plan to burn and the proximity of houses, roads, and other smoke sensitive sites to the planned burn area. The burn prescription is then written to mitigate negative impacts of smoke, especially to individuals who may be smoke-sensitive. Smoke, however, is a natural byproduct of fire and some amounts are unavoidable.

Periodic prescribed burns prevent heavy fuel accumulation that would send a larger amount of smoke into the air should an uncontrolled wildfire occur.

Once the day of the burn arrives, crews head out to the site to lay out hoses and prepare for ignition. Today, John Castaneda, the prescribed fire boss trainee, led the men and women assigned to the engines through the plan for the day. The "No, No Go" list covers wind and temperature conditions, air pressure and cloud cover. He assigns the EMT for the day and informs everyone where a helicopter would land should an emergency occur. He assigns positions and determines water supply. They have water tender trucks on the scene, but water today will be pumped from the river.

The next step is a fire test that will help them decide their lighting pattern for the day.

They don't want the fire to hurt whats in the burn area, though some spreading is okay. The goal is to reduce fuels while containing the fire's footprint.

"Our goat is to return the forest to how it used to be," said Soldavini.

The problem is that trees are now too close together, a problem that started with the clear cutting of the Lake Tahoe Basin in the mid- to late 1800s. There used to be just 40 to 60 trees per acre, while we now have an average of 151 trees per acre. The dominant trees were the Jeffrey and Ponderosa Pines with an understory of cedar and white fir. When the trees were clearcut, their seeds were spread over the landscape, creating new, and thick, growth.

In the seven years between 2000 and 2007, 13,447 acres were burned in the Lake Tahoe Basin Management Unit area. Over the next five years, that number jumped to 17,678 acres.

There will be prescribed burns from Fall through Spring, as favorable conditions exist. USFS has been able to, at times, have burns in the summer months when it was a lot of rain and higher humidity.