[MCN] Forest losing capacity to recover after fire: Past no guide to future

Lance Olsen lance at wildrockies.org
Wed Sep 7 10:52:10 EDT 2016

Thrive or fail: Examining forest resilience in the face of fires

Other studies by her research group have shown that years of hot, dry 
climate immediately following fires significantly impede forest 

"This is a new normal. We have to anticipate how things are going to 
change," says Turner.

MADISON, Wis. -- In 1988, fires consumed more than a million acres of 
Yellowstone National Park and its surrounding lands. But for the past 
three decades, Yellowstone's forests -- resilient ecosystems composed 
of species adapted to periodic severe fire -- have embarked on their 

However, this year, several new fires -- including the Maple, Buffalo 
and Berry fires -- are burning through those young pine forests. 
Typically, a century or more separates severe wildfires there, says 
Monica Turner, professor of zoology at the University of 
Wisconsin-Madison, so how the forest will recover from more fire just 
28 years later is unknown.

Turner paired with Jill Johnstone, professor of biology at the 
University of Saskatchewan, to outline a framework this month in the 
journal Frontiers in Ecology and the Environment to help scientists 
better test, understand and predict when forests are resilient enough 
to recover or when a combination of conditions could tip the scales, 
drastically altering forest landscapes.

"This is a new normal. We have to anticipate how things are going to 
change," says Turner.

Turner and Johnstone, who studies the boreal forests of Alaska and 
Canada, view the framework as a tool for ecologists to better 
accomplish this because how the forests of the future will be 
affected by traditional disturbances like fire in the context of 
changing conditions -- from a warmer, drier climate to destruction by 
invasive species -- remains a challenge to predict.

"We have to look at disturbances today and try to understand their 
effects because we can't afford to wait 30, 40, 50 years to see 
what's going to happen," says Turner, who has studied the forests of 
Yellowstone since the last of the 1988 flames fizzled. She's been 
fascinated with their recovery and how they have also been resilient 
to outbreaks of mountain pine beetles. However, she has also learned 
that warming climate and drought may be changing the rules of the 
game. "Having all the answers will take decades and we want to find 
creative ways to get answers sooner."

Especially since hot and dry conditions have fueled wildfires in 
populous portions of California this summer, destroying homes and 
forcing tens of thousands of people to evacuate. And some of the 
largest fires of the season continue to burn in Idaho and Washington.

Johnstone and Turner, co-lead authors of the framework, assembled a 
team of leading forest ecologists -- including three UW-Madison 
alumni -- to develop it. In their analysis, they highlight the notion 
of ecological memory, which refers to the evolved adaptations of 
forests to fire, such as the presence of pine cones (serotinous 
cones) that only open in response to fire (what the researchers call 
"information legacies"), to what is left after disturbances, like the 
dead trees that remain standing after a blaze ("material legacies").

Ecological memory confers forests with resilience to fire by 
providing them the building blocks for recovery, even under a wide 
range of conditions.

By definition, disturbances are almost always unpredictable but "what 
we and many others want to know is whether there are situations where 
forests may be stressed beyond their ability to be resilient, where a 
double or triple whammy will have a big effect," says Turner.

For instance, she will continue to study Yellowstone in the wake of 
this year's fires, to see if burned forest areas can recover after a 
growth period of just 28 years. Other studies by her research group 
have shown that years of hot, dry climate immediately following fires 
significantly impede forest recovery.

Johnstone has shown that areas of boreal forest once occupied by 
white spruce have been invaded by flammable black spruce, increasing 
fire frequency in areas unaccustomed to flames, while some severely 
burned areas have been repopulated by less flammable species, 
reducing fires there.

In Minnesota, severe wind storms that knock serotinous cones to the 
forest floor can prevent forests from recovering if a fire follows. 
And in New Zealand, some forests are seeing fires for the first time 
due to human impact; the species there have not had the opportunity 
or time to adapt to fire.

"If the new normal is outside of the conditions they are adapted to, 
forests may no longer be resilient," says Turner, because it results 
in a mismatch between ecological memory and the disturbances forests 

This mismatch can lead to what Turner and her co-authors dub 
"resilience debt," which becomes apparent only after a disturbance 
occurs. Ecological processes happen slowly, so the impact of 
disturbances, though they happen fast, could take years or even 
decades to manifest
By examining different mechanisms that have diminished the ability of 
forests to recover -- from a change in disturbance frequency, size or 
severity to changing climate -- Turner and her colleagues were able 
to define particular sets of conditions that may allow ecologists to 
predict when forests will be resilient or when they will be 
fundamentally altered.

"I am excited because we have been working out these ideas for the 
last five years or so and it's nice to have a framework to test a lot 
of these ideas for how generalizable they are," Turner says. 
"Ultimately, it's the data that will tell us."

Thanks to support from the federal Joint Fire Science Program, Turner 
has new funding to test some of these ideas about resilience in the 
Rocky Mountains.

She and colleagues at UW-Madison, including Jack Williams, director 
of the Center for Climatic Research and a professor of geography; 
Stephen Carpenter, director of the Center for Limnology and professor 
of zoology; Anthony Ives, professor of zoology; and Chris Kucharik, 
professor of agronomy at the Nelson Institute for Environmental 
Studies, are also leading a new effort with support from the UW2020: 
WARF Discovery Initiative to focus on abrupt changes in ecological 
systems of the U.S. They refer to their project as ACES.

"It's not only western forests where these things matter, where 
disturbances and changing environments shape regional landscapes," 
Turner adds. "With ACES, we want to assess the possibility of fast 
changes in forests, lakes and agriculture to help us anticipate the 
effects on wildlife, carbon storage, water quality, and future timber 
resources. These things matter a lot."
"The biosphere -- this thin film of air and water and soil and life 
no deeper than ten miles, or one four-hundredth of the earth's radius 
-- is now the setting of the uncertain history of man."

"Man must learn to see himself in his true place and proportion in 
the biosphere."

  The Editors, Scientific American. Foreword to The Biosphere, the 
book version of Scientific American's September 1970 special issue on 
The Biosphere.
"The growth in CO2 emissions closely follows the growth in Gross 
Domestic Product (GDP) corrected for improvements in energy 

P. Friedlingstein, et al. "Update on CO2 emissions."
Nature Geoscience. Published online: 21 November 2010
"Changes in world GDP (WGDP) have a significant effect on CO2 
concentrations, so that years of above-trend WGDP are years of 
greater rise of CO2 concentrations."

Granados et al. Climate change and the world economy: short-run 
determinants of atmospheric CO2. Environmental science & policy 21 
(2012) 50-62

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