[MCN] A long look back at fire in the Sierra Nevada

[Lance Olsen]

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"Large shifts in the fire record corresponded with socio-ecological 
change, and not climate change, and socio-ecological conditions 
amplified and buffered fire response to climate," the researchers 
report in today's (Nov. 14) issue of the Proceedings of the National 
Academy of Sciences.
<<http://www.pnas.org/content/early/2016/11/08/1609775113.abstract>>

"The Native American mosaic of burned and unburned area prevented 
fires from continuously spreading."

"Before the Native American die off, fires burned 4.5 times more area 
than they do today," said Taylor. "After the Native American 
depopulation fires burned 8 times more area than they do today."

"We did eventually develop an understanding of how climate patterns 
could be used to develop long-lead forecasts," said Taylor. "But 
there has to be a consideration of both people and climate to predict 
and plan for future fire activity."
========================

Human actions influence fire regimes in the Sierra Nevadas
PENN STATE  PUBLIC RELEASE: 14-NOV-2016

While climate contributes strongly to fire activity in the Sierra 
Nevada mountains of the western U.S., human activity, starting well 
before European contact, has also played an important part in the 
severity, frequency and sheer numbers of forest fires occurring in 
the area, according to researchers.

"Initially, we did work to see if we could develop long-lead 
forecasts for fire in the area -- six to 18 months in the future -- 
using climate patterns such as El Nino," said Alan H. Taylor, 
professor of geography, Penn State. "This would be a significant help 
because we could place resources in the west if forecasts indicated 
it would be dry and the southeast would be wet. However, the climate 
relationships with fire did not consistently track."

Taylor, working with Valerie Trouet, associate professor of 
dendrochronology, University of Arizona, merged a tree-ring-based 
record of Sierra Nevada fire history with a 20th century record based 
on annual area burned to create a record of fires spanning 415 years, 
from 1600 to 2015. While year-to-year fire variability was influenced 
by climate throughout that time, they found that large decadal-scale 
shifts in the Sierra Nevada fire regime were related to changes in 
human activity.
"Large shifts in the fire record corresponded with socio-ecological 
change, and not climate change, and socio-ecological conditions 
amplified and buffered fire response to climate," the researchers 
report in today's (Nov. 14) issue of the Proceedings of the National 
Academy of Sciences.

The researchers uncovered four time periods, each possessing their 
own fire regime characteristics that, while impacted by climate, were 
also heavily influenced by human land use patterns. The earliest fire 
regime period, dating from 1600 to 1775, corresponded to the time 
before Europeans came to the California area. During this time, 
Native Americans used fire to improve the production of acorns, 
tubers, shrubs and game such as deer. Their burn regime also 
controlled the amount of fuel on the forest floor. Native Americans 
who used the Sierra Nevada forests created a mosaic of small burned 
areas interwoven with unburned forest.

Early fires, because they were more frequent with less fuel build-up, 
were "good" fires. They burned through the forest, consumed 
understory fuels and left the majority of trees unharmed. The Native 
American mosaic of burned and unburned area prevented fires from 
continuously spreading.

 From 1776 to 1865 the second fire regime, characterized by Spanish 
colonialism and the depopulation of Native Americans in the area 
shows more land burned. European settlers brought diseases against 
which Native Americans had no immunity and the population suffered. 
The Spanish built a string of missions in California beginning in 
1769 and relocated remaining Native Americans to the mission areas. 
In 1793, there was a ban on burning to preserve forage, disrupting 
the pre-colonial Native American burning practices. The incidence of 
fires became more sensitive to drought and the fire regime changed, 
creating a time when fires were largest and most closely coupled with 
climate.

"Before the Native American die off, fires burned 4.5 times more area 
than they do today," said Taylor. "After the Native American 
depopulation fires burned 8 times more area than they do today."

The third fire period is from 1866 to 1903 and was initiated by the 
California gold rush, when thousands of people poured into the area. 
Settlement by large numbers of new immigrants began to break up the 
forest fuel and the creation of large herds of animals, especially 
sheep, removed large amounts of understory and changed the fire 
regime.

The fourth fire period began in 1904 and is linked to the federal 
government's policy of fire suppression on government lands. The 
reason pre-colonial and Spanish colonial fire levels were so much 
higher than today is that the current fire regime is one of 
suppressions with an extremely low incidence of fires compared to the 
past. However, suppression over the last century has allowed fuel to 
build up on the forest floor and opened the door for "bad" fires that 
destroy the forest canopy and burn large areas of land.

"Fire was locked in with decadal temperature variation until about 
1860, after which time the relationship decays until the 1980s, when 
fire tracks temperature again," said Taylor.

The decay occurred because people changed the landscape through 
grazing and then changed the forests by suppressing fire.

Today's fires, according to Taylor, can be "bad" fires because a 
century or more of fire suppression has created a vast store of fuel 
to accumulate on the forest floor, allowing fires to burn long enough 
and hot enough to kill the forest canopy. These fires are also harder 
to fight.

"It is important for people to understand that fires in the past were 
not necessarily the same as they are today," said Taylor. "They were 
mostly surface fires. Today we see more canopy-killing fires."

Climate is still an important part of the regional fire regime. 
Extremely dry times will increase fire prevalence and extremely wet 
periods will decrease fires occurrence. But climate alone, in an 
inhabited area, cannot predict the fire regime. The actions of people 
must also be considered.

"We did eventually develop an understanding of how climate patterns 
could be used to develop long-lead forecasts," said Taylor. "But 
there has to be a consideration of both people and climate to predict 
and plan for future fire activity."
###
Also working on this project were Carl N. Skinner, geographer, 
Pacific Southwest Research Station, U.S. Forest Service and Scott L. 
Stephens, professor of environmental science, policy and management, 
University of California, Berkeley.

The U.S. Forest Service supported this research.

-- 
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"Trump promised to "cancel" the international climate change accord 
in his first 100 days of office. Seeing that the deal went into 
effect last week, he will have to wait  ... . But in the meantime, 
the United States could severely handicap the deal by not following 
through on emissions cuts and reneging on promised funds for global 
climate adaptation."

http://grist.org/politics/trump-will-be-the-fossil-fuel-industrys-greatest-gift/
========================================================================
"Congress offers change without change -- a green economy built on 
cheap coal and petrol -- because that is what voters want. Is it too 
much to ask that Mr Obama should tell voters the truth? I think he 
could do it. He has everything it takes to be a strong president. He 
is choosing to be a weak one."

Clive Crook. "Obama is choosing to be a weak president." Financial 
Times, June 28, 2009
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"Everybody knows the ship is sinking. Everybody knows the captain lies."

Leonard Cohen
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