Fire Suppression, Let-Burn, or Prescribed Burns? Or all three?
Fire Suppression, Let-Burn, or Prescribed Burns? Or all three?
There are two inter-related issues that should be considered here: 1) The fire policies that are followed or mandated on our public lands and (2) Those that can be implemented in our fire-threatened, local communities, usually lower in the foothills where people own their own property and homes.
In the former, we look to the policies of the National Park Service (NPS), like those in Yosemite, where they often allow naturally ignited fires to burn until they go out on their own.
However if changing conditions bring severe threats to public safety such as in the 2014 Meadow Fire which was ignited by lightning on July 19th and smoldered for weeks between Glacier Point and the Clark Range, consuming fuels that had accumulated over many years. However, on Sept. 7th, winds from the south blew the fire up to intensities that threatened hikers who had attained the summit of Half Dome.
Taken from Glacier Point with Mt. Clark in the background, one can see the beginnings of the eruption of fire that developed during that day. Trapped on Half Dome, the hikers were rescued by helicopter and were brought to Ahwahnee Meadow on Yosemite Valley’s floor.
A short while later when we arrived at Tunnel View, the scene looked like this, with the smoke billowing and the pyro-cumulus cloud forming, caused by the heat of the fire driving the air aloft, cooling as it rises, condensing water vapor into the cloud’s liquid water droplets.
Arriving at Ahwahnee Meadow, we witnessed the arriving hikers who’d been rescued from Half Dome’s summit.
When we reached Valley View, the pyro-cumulus cloud was well-developed, and we were pleased that no one had been injured during what must have been an exciting day for the Half Dome hikers.
Most of us have seen images of expensive and hard-driving fire suppression. Even in Yosemite, it is sometimes used. An example would be the Indian Canyon fire of 2015 when huge jet tankers dropped plane-loads of retardant on the burning forests above Yosemite Valley.
One example of a prescribed burn was the Taft Toe Prescribed Burn that was ignited intentionally on the floor of Yosemite Valley by NPS personnel on Oct. 15, 2015. The goal was to use fire as an ecosystem restoration and management tool. In the absence of fire, the density of shade-tolerant trees such as white fir and incense cedar, along with forest floor litter accumulations bring conditions to unnatural and unacceptable levels. The purposes of a prescribed burn are to reduce the density of small diameter (less than six-inch), mixed conifer trees, accumulations of dead and down woody debris, and to restore and maintain the open forests and meadows.
Ignited by “drip-torches,” at various intervals from Southside Drive, upslope, smoke was carried away from the traffic, maintaining visitor safety.
Readily burnable fuels of all sizes are consumed, eliminating understory fuels and reducing the density of shade-tolerant trees.
Another prescribed burn example is the Ahwahnee Meadow Burn that was ignited 9/12/16. Here the objectives included restoring & maintaining the meadow’s character and reducing the density of shade-tolerant trees under the forest canopy that surrounds the meadow. Above, one can see how the smoke-filled upper Yosemite Valley, dispersed upward, yet didn’t impact the lower valley where visitors could find lovely smoke-free localities to enjoy. On most summer afternoons, the up-valley breezes are a predictable, daily occurrence.
Two days later, NPS-Fire was still evaluating the burn, and interpretive signs were already in place, a sign of good planning.
Where the burn entered the forest, undesirable shrubs and small trees were consumed.
From these examples we can appreciate the thoughtfulness and care that the NPS has invested in, not only managing their own lands, balancing plant ecology, fire resilience, and human enjoyment and safety, but pointing the way for other public land agencies to utilize prescribed burning to reduce the threats to our other public lands.
We will next turn our attention to reducing fires’ threats to our homes and communities in the lower elevations of the Sierra foothills where private lands and homes are more common.