Subscribe to our free daily newsletters
. Earth Science News .




Subscribe to our free daily newsletters



WOOD PILE
North American forests unlikely to save us from climate change
by Staff Writers
Tucson AZ (SPX) Jul 21, 2016


illustration only

Forests take up 25 - 30 percent of human-caused emissions of carbon dioxide - a strong greenhouse gas - and are therefore considered to play a crucial role in mitigating the speed and magnitude of climate change. However, a new study that combines future climate model projections, historic tree-ring records across the entire continent of North America, and how the growth rates of trees may respond to a higher concentration of carbon dioxide in the atmosphere has shown that the mitigation effect of forests will likely be much smaller in the future than previously suggested.

Published in the journal Ecology Letters, the study is the first to reveal the possible impact of a changing climate on the growth rate of trees across all of North America, in other words, how their growth changes over time and in response to shifting environmental conditions. The result are detailed forecast maps for the entire North American continent that reveal how forest growth will be impacted by climate change.

The research team, led by scientists at the University of Arizona in Tucson, combined climate projections for North America developed by the International Panel for Climate Change (IPCC) with historic tree-ring records based on samples covering the period 1900 to 1950 at 1,457 sampling sites across the continent.

"We then looked at how the growth of those trees changed historically under various past climates and used that to predict how they will grow in the future across the continent all the way from Mexico to Alaska," said the study's first author, Noah Charney, a postdoctoral research associate in UA's Department of Ecology and Evolutionary Biology.

"The research is unprecedented and novel in the use of big biological data," said co-author Brian Enquist, a professor in the UA's Department of Ecology and Evolutionary Biology and a fellow of the Aspen Center for Environmental Studies in Aspen, Colorado. "We utilized a network of more than two million tree-ring observations spanning North America. Tree-rings provide a record into how trees that grow in different climates respond to changes in temperature and rainfall."

The study calls into question previous conclusions about how forests will respond to warmer average temperatures, increased greenhouse gas emissions, and shifting rainfall patterns.

The team was startled to find no evidence for a greenhouse-gas absorbing process called the boreal greening effect in their simulations. Boreal greening refers to the assumption that trees in high latitudes, where colder temperatures limit growth, should benefit from warmer temperatures and higher concentrations of carbon dioxide in the atmosphere and, as a result, "green" under the effects of climate change. In turn, these thriving boreal forests should be able to scrub more carbon dioxide from the atmosphere, so goes the idea, dampening climate change.

"Until now, there wasn't a good way to take into account how trees respond to climate change under novel climate conditions," added senior author Margaret Evans, an assistant research professor in the UA's Laboratory of Tree-Ring Research (LTRR) and the UA's Department of Ecology and Evolutionary Biology. "Our study provides that perspective. We see that as trees are pushed under the effect of climate change, their response changes."

"Many previous climate modeling studies counted on the boreal forests to save us from the climatic disaster by offsetting our emissions, but we don't' see any greening in our results," said Valerie Trouet, an associate professor in the LTRR. "Instead, we see browning. The positive influence warmer temperatures are believed to have on boreal forests - we don't see that at all."

The most dramatic changes in projected forest growth rates were found in the interior West of the North American continent, with up to 75 percent slower growth projected for trees in the southwestern U.S., along the Rockies, through interior Canada and Alaska. Increases in growth were seen only along certain coastal areas, mostly in the Pacific Northwest, Northeastern Quebec and the Maritime Provinces and the Florida panhandle.

Some of the predictions arising from the simulations are already happening, the team found.

"In Alaska, for example, where trees have been projected to respond positively to warming temperatures under the boreal greening effect, we see that trees are now responding negatively instead," Evans said. "Trees in very high latitudes are limited by cold temperatures, so yes, in warmer years they grow more, but there is a tipping point, and once they go past that, a warmer climate becomes a bad thing instead of a good thing."

The research indicates that the warming climate already is rapidly pushing many forests towards that tipping point, which may be reached as early as 2050: In addition to being rapidly exposed to temperatures they have not experienced in their lifetimes and are not evolutionarily prepared for, being hampered in their growth makes trees even more vulnerable to added stresses.

"There is a critical and potentially detrimental feedback loop going on here," Charney said. "When the growth rate of trees slows down in response to environmental stressors such as cold or drought, they can get by for a few years, but over time, they deplete their resources and are much more susceptible to additional stressors, such as damage by fire or a big drought or insect outbreaks. Year after year of slow growth therefore means forests become less and less resilient."

As a result, a forest can go from being a climate asset to a carbon producer very quickly.

"It's like a thermostat gone bad," Evans said. "Forests act as a carbon sink by taking carbon dioxide out of atmosphere, but the more the climate is warming, the slower the trees are growing, the less carbon they suck up, the faster the climate is changing."

"The results also highlight the potential importance of locally adapted forest management strategies to help mitigate the decreases in forest growth predicted by our analyses," Charney said.

The implications could potentially apply worldwide. While their models did not include data from outside the North American continent, it "seems very likely that the conclusions drawn in this study apply in the Eurasian forest as well," Evans said. "The boreal forests in Eurasia are more extensive and even more important than the ones in continental North America."

Research paper: "Observed forest sensitivity to climate implies large changes in 21st century North American forest growth,"


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

.


Related Links
University of Arizona
Forestry News - Global and Local News, Science and Application






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Previous Report
WOOD PILE
DRCongo to scrap illegal China logging contracts
Kinshasa (AFP) July 13, 2016
Congolese authorities told AFP on Wednesday they would annul three logging contracts awarded to China last year in what Greenpeace had called a violation of Congo's own logging moratorium. The August 2015 attribution of three licences covering 650,000 hectares (2,500 square miles) to Chinese-owned firms Somifor and Fodeco was made public on Tuesday by environmental group Greenpeace. In r ... read more


WOOD PILE
Ex-Marine 'assassinated' Baton Rouge cops: police

Ex-Marine 'assassinated' Baton Rouge cops

Natural catastrophe losses up sharply in first half 2016: Munich Re

A new way to detect hidden damage in bridges, roads

WOOD PILE
'Green' electronic materials produced with synthetic biology

Exploring superconducting properties of 3-D printed parts

Learning from the mussel, scientists create a biologically active titanium surface

World's smallest hard disk stores data atom by atom

WOOD PILE
Massive sewage spill forces closure of Los Angeles beaches

Uproar as Albania to dam Europe's 'wildest river'

China has 'no historic rights' in South China Sea: tribunal

After decades of clean up attempts, world's lakes still suffer from phosphorus pollution

WOOD PILE
Ocean warming to blame for Antarctic Peninsula glacier retreat

More Chinese vessels to sail the Arctic: shipping firm

Expanding Antarctic sea ice linked to natural variability

King penguins keep an ear out for predators

WOOD PILE
Scientists sequence genome of 6,000-year-old barley

Researchers build trenches to curb nitrogen runoff, algae growth

How plants can grow on salt-affected soils

Subtropical Cornwall climate could mean exotic new crops

WOOD PILE
Tokyo jolted by third quake in four days

Tropical storm kills 69 in China

Record-breaking volcanic kettle on Iceland explored

Better understanding post-earthquake fault movement

WOOD PILE
Armed group kills 17 soldiers at Mali base: ministry

Bashir reshuffles senior Sudanese military officials: army

Low uptake of space technology science slows Africa's growth: experts

Rwanda hikes import duties on secondhand clothes

WOOD PILE
Technological and cultural innovations amongst early humans not sparked by climate change

Genomes from Zagros mountains reveal different Neolithic ancestry

Cave art reveals religious encounters between Europeans and Native Americans

Changes in primate teeth linked to rise of monkeys




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News






The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement