Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study Ties Forest "Greenness" in Western U.S. to Snowpack Extent

11.09.2012
Mid-elevation mountain ecosystems most sensitive to rising temperatures and changes in snowmelt

Results of a new study tie forest "greenness" in the western United States to fluctuating year-to-year snowpack extent.


A Sierra Nevada forest in Sequoia National Park: snow depth and forest pattern are related.

The results show that mid-elevation mountain ecosystems are the most sensitive to rising temperatures and to changes in precipitation and snowmelt.

University of Colorado-Boulder scientist Noah Molotch and colleagues used satellite images and ground measurements to identify the threshold at which mid-level forests sustained by moisture change to higher-elevation forests sustained by sunlight.

A paper reporting the results was published yesterday in the journal Nature Geoscience.

Molotch is the lead author. Co-authors are Ernesto Trujillo of the University of Colorado-Boulder and Ecole Polytechnique Fédérale de Lausanne in Switzerland; Michael Golden and Anne Kelly of the University of California, Irvine; and Roger Bales of the University of California, Merced.

"The research demonstrates yet another complexity in the response of mountain ecosystems to increasing temperatures," says hydrologist Tom Torgersen, program director in the National Science Foundation's Division of Earth Sciences, which funded the research. "High-elevation mountain forests are typically temperature-stressed and low-elevation mountain forests are often water-stressed.

"At mid-elevations, 'everything is just right'--until it goes wrong." Torgersen says, "Higher temperatures lead to reduced snowpack and reduced water availability, leaving trees at mid-elevations more stressed and more prone to fires."

The ability to identify this "tipping point" is important, Molotch says, because mid-level forests--at altitudes from roughly 6,500 feet to 8,000 feet--are where many people live and visit. They're also linked with increasing wildfires, beetle outbreaks and rising tree mortality.

"These results provide the first direct observations of snowpack-forest connections across broad scales," says Molotch.

"Finding the tipping point between water-limited [mid-elevation] forests and energy-limited [high-elevation] forests defines the region of the greatest sensitivity to climate change--the mid-elevation forests--which is where we should focus future research," he says.

Although the research took place in the Sierra Nevada mountain range in California, it's applicable to other mountain ranges across the West.

Climate studies show that the snowpack in mid-elevation forests in the western United States and other forests around the world has been decreasing over the past 50 years because of regional warming.

"We found that mid-elevation forests show a dramatic sensitivity to snow that fell the previous winter in terms of accumulation and subsequent melt," said Molotch, also a scientist at NASA's Jet Propulsion Laboratory in Pasadena.

"If snowpack declines, forests become more stressed, which can lead to ecological changes in the distribution and abundance of plant and animal species, and to more vulnerability to fires and to beetle kill."

Molotch says that about 50 percent of the greenness seen by satellites in mid-elevation forests is linked with maximum snow accumulation from the previous winter, with the other 50 percent related to soil depth, soil nutrients, temperature and sunlight.

"The strength of the relationship between forest greenness and snowpack from the previous year is very surprising," Molotch says.

The researchers initially set out to identify the various components of drought that lead to vegetation stress.

"We went after mountain snowpacks in the western U.S. because they provide about 60 to 80 percent of the water in high-elevation mountains," says Molotch.

The team used 26 years of continuous data from the Advanced Very High Resolution Radiometer, a space-borne sensor flying on a National Oceanic and Atmospheric Administration satellite, to measure the forest greenness.

The researchers compared it with long-term data from 117 snow stations maintained by the California Cooperative Snow Survey, a consortium of state and federal agencies.

In addition, the scientists used information gathered from "flux towers" in the southern Sierra Nevada mountain range. Instruments on these towers measure the exchanges of carbon dioxide, water vapor and energy between the land and the atmosphere.

Instruments on the towers, which are some 100 feet high, allowed scientists to measure the sensitivity of both mid-level and high-level mountainous regions to both wet and dry years--data that matched up well with the satellite and ground data.

"The implications of this study are profound when you think about the potential for ecological change in mountain environments in the West," says Molotch.

"If we look ahead to the time when climate models are calling for warming and drying conditions, the implication is that forests will be increasingly water-stressed in the future and more vulnerable to fires and insect outbreaks."

In the context of recent forest losses to fire in Colorado and elsewhere, the findings are something that really deserve attention, Molotch says.

"This tipping-point elevation is very likely going to migrate up the mountainsides as climate warms."

The research was also funded by NASA.

-NSF-

Media Contacts
Cheryl Dybas, NSF (703) 292-7734 cdybas@nsf.gov
Jim Scott, University of Colorado-Boulder (303) 492-3114 jim.scott@colorado.edu
Related Websites
NSF discovery article: A Tree Stands in the Sierra Nevada: http://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=125091&org=NSF
NSF Southern Sierra Critical Zone Observatory: https://eng.ucmerced.edu/czo/index.html

NSF Critical Zone Observatories: Where Rock Meets Life: http://www.criticalzone.org/

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2012, its budget is $7.0 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives over 50,000 competitive requests for funding, and makes about 11,000 new funding awards. NSF also awards nearly $420 million in professional and service contracts yearly.

Cheryl Dybas | EurekAlert!
Further information:
http://www.nsf.gov
http://nsf.gov/news/news_summ.jsp?cntn_id=125359&org=NSF&from=news

More articles from Earth Sciences:

nachricht Sediment from Himalayas may have made 2004 Indian Ocean earthquake more severe
26.05.2017 | Oregon State University

nachricht Devils Hole: Ancient Traces of Climate History
24.05.2017 | Universität Innsbruck

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

How herpesviruses win the footrace against the immune system

26.05.2017 | Life Sciences

Water forms 'spine of hydration' around DNA, group finds

26.05.2017 | Life Sciences

First Juno science results supported by University of Leicester's Jupiter 'forecast'

26.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>