UMD Researchers Use Space Laser Technology to Explain Dry Season Growth in Amazon Rainforest

UMD Researchers Use Space Laser Technology to Explain Dry Season Growth in Amazon Rainforest

For more than a decade, scientists have debated what’s known as the “green up” phenomenon in the Amazon rainforest—when vegetation appears to thrive and grow fuller during the dry season with little or no rainfall. While some researchers have supported hypotheses that drought-induced growth does occur in the Amazon, others have argued it is more likely an optical illusion created by shadows cast from satellite positioning.

New research from the University of Maryland Department of Geographical Sciences published in the Proceedings of the National Academies of Sciences(PNAS) utilizes lidar satellite technology to more accurately measure seasonal changes in leaf area within the Amazon. Research Associate Hao Tang and Professor Ralph Dubayah analyzed data sets collected from NASA’s Geoscience Laser Altimeter System (GLAS) and found strong evidence of green up during the dry season in both the tree canopy and the underbrush; just not at the same time.

“Trees in the Amazon forests not only respond to seasonal environmental changes, but also have active ecological interactions as a community,” Tang said. “Tall trees grow leaves at the early dry season when both water and light are abundant; they then drop leaves during the mid-to-late dry season, not only protecting themselves from drought but also helping understory and small trees grow.”

“This pattern is easily missed if you average over the entire Amazon basin because it progresses, almost like a wave, from south to north, with the dry season,” Dubayah added. “There is a plausible, ecological explanation for this: Light is driving the growth of the canopy in the early dry season and light from small gaps in the canopy that form later in the dry season drive the growth of the small shrubs and trees near the forest floor.”

The UMD researchers stress the need for better lidar observations of the Amazon’s canopy structure from space in order to more fully understand how rainforests respond to environmental and climate changes. Dubayah leads UMD’s Global Ecosystem Dynamics Investigation (GEDI), a NASA-funded mission to place a multi-beam laser instrument on the International Space Station in late 2018.

“The GEDI mission is optimized precisely to make these kinds of difficult measurements possible. It will provide more than 15 billion cloud-free observations during its 18-month mission and should greatly enhance our ability to understand canopy dynamics in the Amazon and elsewhere,” Dubayah said.  


Photo caption: Seasonal changes in canopy and understory over the Amazon

February 22, 2017


Prev   Next

Current Headlines

Faculty and Staff Convene for Research Impact Workshop

Start-up Born in UMD FPE Receives $1.2M Investment from Newly Established Maryland Momentum Fund

UMD Researchers Develop New Method for Electrogenic Devices to Control Cell Behavior

UMD Welcomes New VP for Research, Unveils New Vision for Strategic Impact

UMCP and UMB Celebrate 10 Years of Collaboration and MPowering the State

University of Maryland Announces Unprecedented Investment from the A. James & Alice B. Clark Foundation

UMD Awarded U.S. Department of Commerce Grant to Launch Immersive Media Innovation Ecosystem

UMD Research Administration Leader Receives Distinguished Service Award

News Resources

Return to Newsroom

Search News

Archived News

Events Resources

Events Calendar

Additional Resources

UM Newsdesk

Faculty Experts

Connect

social iconstwitterlinkedinrssYouTube
Division of Research
University of Maryland
College Park, MD 20742-1541

Email: vpr@umd.edu
© Copyright 2017 University of Maryland

Did You Know

UMD is a member of the Association of American Universities, comprised of 61 leading research universities in the U.S. & Canada.