Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Handful of Heavyweight Trees Per Acre Are Forest Champs

04.05.2012
Big trees three or more feet in diameter accounted for nearly half the biomass measured at a Yosemite National Park site, yet represented only one percent of the trees growing there.

This means just a few towering white fir, sugar pine and incense cedars per acre at the Yosemite site are disproportionately responsible for photosynthesis, converting carbon dioxide into plant tissue and sequestering that carbon in the forest, sometimes for centuries, according to James Lutz, a University of Washington research scientist in environmental and forest sciences. He's lead author of a paper on the largest quantitative study yet of the importance of big trees in temperate forests being published online May 2 on PLoS ONE.

"In a forest comprised of younger trees that are generally the same age, if you lose one percent of the trees, you lose one percent of the biomass," he said. "In a forest with large trees like the one we studied, if you lose one percent of the trees, you could lose half the biomass."

In 2009, scientists including Lutz reported that the density of large-diameter trees declined nearly 25 percent between the 1930s and 1990s in Yosemite National Park, even though the area was never logged. Scientists including co-author Andrew Larson of the University of Montana, also have found notable numbers of large trees dying in similar areas across the West.

Because of this, scientists have been keen to study a plot large enough to detect forest ecosystem changes involving large trees, including the effects of climate variability and change, possible culprits in the declines, Lutz said.

The new 63-acre study site in the western part of Yosemite National Park is one of the largest, fully-mapped plots in the world and the largest old-growth plot in North America. The tally of what's there, including the counting and tagging of 34,500 live trees, was done by citizen scientists, mainly undergraduate college students, led by Lutz, Larson, Mark Swanson of Washington State University and James Freund of the UW.

Included was all above-ground biomass such as live trees, snags, downed woody debris, litter and what's called duff, the decaying plant matter on the ground under trees. Even when big trees die, they continue to dominate biomass in different ways. For example, 12 percent of standing snags were the remains of large-diameter trees, but still accounted for 60 percent of the total biomass of snags.

Live and dead biomass totaled 280 tons per acre (652 metric tons per hectare), a figure unmatched by any other forest in the Smithsonian Center for Tropical Forest Science network, a global network of 42 tropical and temperate forest plots including the one in Yosemite.

Trees in the western U.S. with trunks more than three feet across are typically at least 200 years old. Many forests that were heavily harvested in the 19th and 20th centuries, or those that are used as commercial forest lands today, don't generally have large-diameter trees, snags or large wood on the ground.

One implication of the research is that land managers may want to pay more attention to existing big trees, the co-authors said. Last year in the Yosemite National Park, for example, managers planning to set fires to clear out overgrown brush and densely packed small trees first used data from the study plot to figure out how many large trees to protect.

"Before the fires were started, crews raked around some of the large trees so debris wouldn't just sit and burn at the base of the tree and kill the cambium, the tissue under the bark that sustains trees," Lutz said.

In some younger forests that lack big trees, citizens and land managers might want to consider fostering the growth of a few big-trunked trees, Lutz said.

Another finding from the new work is that forest models based either on scaling theory or competition theory, which are useful for younger, more uniform forests, fail to capture how and where large trees occur in forests.

"These trees started growing in the Little Ice Age," Lutz said. "Current models can't fully capture the hundreds of years of dynamic processes that have shaped them during their lifetimes."

The research was funded by the Smithsonian Center for Tropical Forest Science.

For more information:
Lutz, 206-616-3827, jlutz@uw.edu
Facebook page for Yosemite plot
http://www.facebook.com/pages/Yosemite-Forest-Dynamics-Plot/117620576445
After embargo lifts 2 p.m. PT (5 p.m. ET), May 2, article is available at
http://dx.plos.org/10.1371/journal.pone.0036131
Suggested websites
Jim Lutz
http://faculty.washington.edu/jlutz/
PLos One
http://www.plosone.org/home.action
Andrew Larson
http://www.cfc.umt.edu/Personnel/Details.php?ID=1710
Homepage for Yosemite plot
http://depts.washington.edu/yfdp/
Yosemite National Park
http://www.nps.gov/yose/index.htm
Citizen scientists
http://depts.washington.edu/yfdp/peoplePage.php?q=2011
Mark Swanson
http://www.natural-resources.wsu.edu/people/faculty/swanson.html
Smithsonian Center for Tropical Forest Science
http://www.ctfs.si.edu/

Sandra Hines | Newswise Science News
Further information:
http://www.uw.edu

More articles from Agricultural and Forestry Science:

nachricht Microjet generator for highly viscous fluids
13.02.2018 | Tokyo University of Agriculture and Technology

nachricht Sweet route to greater yields
08.02.2018 | Rothamsted Research

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

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

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Stiffness matters

22.02.2018 | Life Sciences

Magnetic field traces gas and dust swirling around supermassive black hole

22.02.2018 | Physics and Astronomy

First evidence of surprising ocean warming around Galápagos corals

22.02.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>