New Laser Technique Will Help Scientists Learn More About Forest Changes

November 15, 1996

CHARLOTTESVILLE, Va., Nov. 16 -- A new technique for gaining a three-dimensional picture of forest canopies may help answer both practical needs of forest managers and basic questions about the relationship between forests and global climate change.

The system, developed by University of Virginia environmental sciences graduate student Michael Lefsky and scientists from NASA and the Smithsonian Environmental Research Center, employs laser radars (lidar) suspended from low-flying airplanes to rapidly and accurately assess the trees' shapes. It is called Scanning Lidar Imager of Canopies by Echo Recovery (SLICER).

"Large scale surveys using SLICER could, for the first time, accurately predict the current storage of carbon in forest stands and their capacity to act a source and sink for carbon dioxide," says Lefsky, whose research concerns the physiological ecology of plants with emphasis on landscape-scale processes.

SLICER works like this: A plane flies over a forest at a height of five kilometers, sending out laser pulses; the beams bounce off layers of foliage and the ground and then return to the plane's bottom-mounted telescopes. The reflected light returns to the telescopes at slightly differing times, depending on the distance it transversed. Lefsky developed the mathematical algorithm that turns this raw laser data into an estimate of the canopy's shape.

According to its developers, SLICER is as accurate as the standard field method of gathering similar data, which takes many hours to perform. In contrast, SLICER can take up to 100 measurements per second to yield a three-dimensional picture of the canopy, and could be used even in dense and remote forests. Moveover, SLICER can predict other forest characteristics, such as the total number and size of the trees.

Information about forest structure is valuable both to forest managers, who may wish to know when the trees reach a marketable size, and to global-change scientists, who study the flow of carbon through the global ecosystem. Carbon, predominantly in the form of gaseous carbon monoxide and carbon dioxide, is one of the elements that contributes to world-wide atmospheric warming. The two principal causes of increased atmospheric carbon dioxide are fossil fuel burning and changes in land use (typically, replacing trees with cropland). Trees bind carbon dioxide in their tissues as they grow. Thus, the numerous rapidly growing trees in a young forest store more carbon that the few, mature trees in an older forest. At present, there is little quantitative understanding of precisely how much young and old forests differ in their capacities to store carbon. SLICER could help answer this question.

Lefsky's partners in this research are Geoffrey Parker, of the Smithsonian Environmental Research Center, and David Harding and J. Brian Blair, of NASA Goddard Space Flight Center. Results of initial experiments carried out at sites in North Carolina and Maryland were presented at a meeting of the Ecological Society of America in August.
November 15, 1996
For more information, contact Michael Lefsky at (804) 982-2333 or
David Harding may be reached at (301) 286-4894 or
Geoffrey Parker may be reached at (301) 261-4190 x210 or
Television reporters should call our TV News Office at (804) 924-7550.

University of Virginia

Related Carbon Articles from Brightsurf:

The biggest trees capture the most carbon: Large trees dominate carbon storage in forests
A recent study examining carbon storage in Pacific Northwest forests demonstrated that although large-diameter trees (21 inches) only comprised 3% of total stems, they accounted for 42% of the total aboveground carbon storage.

Carbon storage from the lab
Researchers at the University of Freiburg established the world's largest collection of moss species for the peat industry and science

Carbon-carbon covalent bonds far more flexible than presumed
A Hokkaido University research group has successfully demonstrated that carbon-carbon (C-C) covalent bonds expand and contract flexibly in response to light and heat.

Metal wires of carbon complete toolbox for carbon-based computers
Carbon-based computers have the potential to be a lot faster and much more energy efficient than silicon-based computers, but 2D graphene and carbon nanotubes have proved challenging to turn into the elements needed to construct transistor circuits.

Cascades with carbon dioxide
Carbon dioxide (CO(2)) is not just an undesirable greenhouse gas, it is also an interesting source of raw materials that are valuable and can be recycled sustainably.

Two-dimensional carbon networks
Lithium-ion batteries usually contain graphitic carbons as anode materials. Scientists have investigated the carbonic nanoweb graphdiyne as a novel two-dimensional carbon network for its suitability in battery applications.

Can wood construction transform cities from carbon source to carbon vault?
A new study by researchers and architects at Yale and the Potsdam Institute for Climate Impact Research predicts that a transition to timber-based wood products in the construction of new housing, buildings, and infrastructure would not only offset enormous amounts of carbon emissions related to concrete and steel production -- it could turn the world's cities into a vast carbon sink.

Investigation of oceanic 'black carbon' uncovers mystery in global carbon cycle
An unexpected finding published today in Nature Communications challenges a long-held assumption about the origin of oceanic black coal, and introduces a tantalizing new mystery: If oceanic black carbon is significantly different from the black carbon found in rivers, where did it come from?

First fully rechargeable carbon dioxide battery with carbon neutrality
Researchers at the University of Illinois at Chicago are the first to show that lithium-carbon dioxide batteries can be designed to operate in a fully rechargeable manner, and they have successfully tested a lithium-carbon dioxide battery prototype running up to 500 consecutive cycles of charge/recharge processes.

How and when was carbon distributed in the Earth?
A magma ocean existing during the core formation is thought to have been highly depleted in carbon due to its high-siderophile (iron loving) behavior.

Read More: Carbon News and Carbon Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to