9. 1871 Peshtigo, Wisconsin
2400 sq. miles
2000 lives lost
1894 Minnesota
100+ sq. miles
900 lives lost
1910 Idaho, Montana “Big Blowup”
3 million acres, 78 to 85 firefighters killed
1918 Minnesota
1500 sq. miles
450 lives lost
1915-”the Ten O’clock Rule"
10. 10 O’clock Rule:
By 10 am the morning after its discovery,
all fires will be extinguished.
The natural fire return interval in Yosemite is
15 years. By 1930 this interval had missed one
complete cycle. The first large fire hits Yosemite in
1948.
Notas do Editor
Columbia point 1899The next three slides show the changes in the amount of forestation that has taken place in Yosemite Valley in 105 years. In 1899 the Indians were regularly burning the valley floor to maintain deer habitat
Columbia point 1961By this time meadow encroachment is obvious. No burning has been allowed for many years
Columbia Point 2006Columbia Point is a well known view point half way up the Yosemite Falls trail.
This shows the suppression zone in pink. In the rest of the park naturally occurring (lightning) fires will be managed forecological benefit
Fire History 1930-2010
The fires burned at a low intensity fires like shown here. The accumulated down branches and trunks were consumed and recycled. To meet the needs of the ecosystem, Yosemite needs to burn 16000 acres per year. Typically the park manages to burn through wild and prescribed fires approx. 10-13000 acres.
This also on the “Backdoor” fire. The accumulated debris is allowing the fire to kill these mature trees. Records show that this forest had not burned since before 1930,75 years. This landscape has missed 7 fire intervals. This is called the Fire Return Interval Departure (FRID)
Same fire with trees crowning and torching. This stand is now dead.
A FRID map for Yosemite. The high country near Tuolumne Meadows has a return interval of 150+ years while the west slope normally burns 10- 15 years. The high country still hasn’t missed its interval while the low country is long overdue.
In the 1960s it was noticed that the stands of Sequoias (Sequoiadendromgiganteum) in the parkwere not replacing themselves. Sequoias are a pseudoserotinous specie, needing fire to reproduce successfully. With the exclusion of fire, no second generation of trees were growing.
Sequoia cones need the heat of fire to open and release their cones and the seedlings need to land in bare mineral soil that has been sterilized by fire.
In 1968 and 9 in a remote area of Kings Canyon National Park, the first prescribed fires were tried. In 1972, Starker Leopold, son of Aldo Leopold and Jan Van Wagtendonk started the first prescribed fire in the Mariposa grove. This picture is of a third reentry burn in the same grove. Visitors can see many young second generation trees.
This is the Mariposa grove burning at a low intensity as night falls on the first day
These two photos show the size of the Sequoia trunks
While adapted to fire with thick resistant bark, Seqoias are not immune. This tree had lost its leader 60-70 years ago and had grown multiple replacement leaders. The crown that resulted collected many feet of dry needles that ignited when a passing ember drifted in. The tree proved to be hollow, fire came out its base and is now about a third the size.
Historically the Native Americans burned Yosemite Valley. In 2006, in a cooperative action to help maintain their culture tribes people ignited a small fire in a prescribed fire unit using traditional methods. Elders each used pinecones to then ignite part of the perimeter before fire crews took over and completed the burn.
A map showing planned prescribed fires in Yosemite Valley
An aerial view of YV22 or the Ahwahnee Meadow. It will burn right up to the lawn of the Ahwahnee Hotel
Proposed burns 2011The Hodgdon burn in the upper left corner was completed, Wawona North west was attempted and shut down due to dry conditions and all valley burns were postponed until after the elections.
Every prescribed fire starts with a test fire to check conditions and fire behavior
Previous prescribed fire in Yosemite Valley
Fire backing through grass
Problems most fire managers don’t have to deal with.
When you do this the political issues get loud.
A night burn in Yosemite Valley. Look for the climbers headlamps on the cliff walls.
