text-only page produced automatically by LIFT Text Transcoder Skip all navigation and go to page contentSkip top navigation and go to directorate navigationSkip top navigation and go to page navigation
National Science Foundation Home National Science Foundation - Geosciences (GEO)
Geosciences (GEO)
design element
GEO Home
About GEO
Funding Opportunities
Awards
News
Events
Discoveries
Publications
Advisory Committee
Career Opportunities
GEO Education Program
See Additional GEO Resources
View GEO Staff
GEO Organizations
Atmospheric and Geospace Sciences (AGS)
Earth Sciences (EAR)
Ocean Sciences (OCE)
Polar Programs (PLR)
Proposals and Awards
Proposal and Award Policies and Procedures Guide
  Introduction
Proposal Preparation and Submission
bullet Grant Proposal Guide
  bullet Grants.gov Application Guide
Award and Administration
bullet Award and Administration Guide
Award Conditions
Other Types of Proposals
Merit Review
NSF Outreach
Policy Office
Additional GEO Resources
GEO Advisory Cmte Report on Ocean Drilling, 2012
GEO Vision, A Report of AC-GEO (10/09)
Strategic Framework for Topical Areas, 2012 (Follow on to GEO Vision)
GEO Education & Diversity Program
GEO Innovation
GEO Data Policies
Follow GEO on Twitter
U.S. Global Change Research Program
Merit Review Broader Impacts Criterion: Representative Activities
Other Site Features
Special Reports
Research Overviews
Multimedia Gallery
Classroom Resources
NSF-Wide Investments

Email this pagePrint this page

Discovery
Granite bedrock and sequoia forests 'communicate' in the Sierra Nevada

Research reveals the coevolution of life and landscapes

granite domes and conifer trees in the mountains

Bald Mountain: Granite domes and conifer trees are linked in the Sierra Nevada's ecosystem.
Credit and Larger Version

April 3, 2014

The following is part eight in a series on the National Science Foundation's Critical Zone Observatories (CZO) Network. Parts one, two, three, four, five, six, and seven are posted on the NSF website.

If a tree falls in the forest and no one is around to hear it, does it make a sound? If it lands on granite bedrock, it does. But beyond the crash of timber onto rock, scientists have found that bedrock and the trees that grow from its weathered soils are, in a sense, communicating.

Bedrock influences forests--and the landscapes of which they are a part--more than was thought, according to researchers funded through the National Science Foundation (NSF) Critical Zone Observatories (CZO) network.

The scientists investigated the factors that influence forest cover in California's Sierra Nevada. Bedrock may be as important as temperature and moisture, they found, in regulating the distribution of trees and other vegetation across mountain slopes.

Geoscientists Cliff Riebe, Jesse Hahm, Claire Lukens and Sayaka Araki of the University of Wyoming recently published results of their study in the journal Proceedings of the National Academy of Sciences (PNAS).

Bedrock and trees in the critical zone

The research took place at the Southern Sierra CZO, one of ten NSF CZOs funded to unearth the secrets of Earth's critical zone.

Critical zone research looks at how water, life, rock and air interact from the base of the soil to the top of the vegetation canopy.

"The CZOs are providing scientists with new knowledge of the critical zone and its response to climate and land-use change," says Enriqueta Barrera, a program director in NSF's Division of Earth Sciences, which funds the CZO network.

"They're the first systems-based observatories dedicated to understanding how Earth's surface processes are coupled," says Barrera. "The results will help us predict how the critical zone affects the ecosystem services on which society depends."

The water cycle, the breakdown of rocks and eventual formation of soil, the evolution of rivers and valleys, patterns of plant growth and landforms that people see all result from processes that take place in the critical zone.

CZO scientists are investigating the integration and coupling of Earth surface processes, and how they are affected by the presence of fresh water.

The researchers are using field and analytical methods, space-based remote sensing and theoretical techniques.

The CZOs add to the environmental sensor networks in place and planned by NSF, including EarthScope, the National Ecological Observatory Network and the Ocean Observatories Network.

Scientists have known that the critical zone is a complex system in which different components interact at various space and time scales, and in which the rates of processes depend on the nature of those interactions.

Until now, however, researchers have looked at the components individually, especially in the field. The CZOs allow for investigation of the critical zone as a holistic system, rather than as isolated parts.

NSF CZOs are located in watersheds in the Southern Sierra Nevada; Boulder Creek in the Colorado Rockies; Susquehanna Shale Hills in Pennsylvania; Christina River Basin on the border of Delaware and Pennsylvania; Luquillo riparian zone in Puerto Rico; Jemez River and Santa Catalina Mountains in New Mexico and Arizona; Piedmont region of South Carolina; Reynolds Creek in Southwest Idaho; Eel River in Northern California; and linked Illinois, Iowa and Minnesota watersheds.

Composition of bedrock limits plant growth

The Southern Sierra CZO is home to extensive forests and huge exposures of granite bedrock.

"We were puzzled by the patchiness of vegetation on mountain slopes," Hahm says. "Densely forested areas are right next to places with little or no trees and soil.

"Strikingly, these bare areas sometimes occur side-by-side with groves of the largest trees on Earth, giant sequoias."

The researchers determined that bedrock composition acts to limit plant growth.

"Unexpectedly, we found that differences in bedrock composition are just as important in this ecosystem as climate," Riebe says. "That's hard to see without spatial analysis tools and integrated datasets on how vegetation and bedrock change across the landscape."

Plants get some of their nutrients from weathering of minerals as bedrock breaks down into soil. Granite rock, it turns out, contains plant-essential nutrients such as phosphorus.

"The results are important because they demonstrate that bedrock geochemistry is on par with climate as a regulator of vegetation in the Sierra Nevada--and likely in other granite mountain ranges around the world," Riebe says.

Geology of 100 million years ago linked with biology of today

Subtle differences in the cooling history of granite 100 million years ago are likely fueling the biogeochemical interactions that produce today's forest patterns.

Understanding these links is at the heart of critical zone science, says Riebe.

The findings also show that variations in forest cover correspond with differences in erosion rates. They appear to affect the pace at which the Sierra Nevada is wearing down due to the action of water, wind and biological processes.

The results will help efforts to learn how mountain forests are responding to climate-linked changes in temperature and precipitation.

"Most studies point to a shift in vegetation toward higher, cooler elevations," Riebe says. "But changes in climate may be just part of the story.

"Any changes in tree distribution will occur only with the consent of the underlying bedrock."

In the Sierra Nevada, rock meets life meets rock. Or life meets rock meets life.

--  Cheryl Dybas, NSF (703) 292-7734 cdybas@nsf.gov

Investigators
Jan Hopmans
Roger Bales
Steven Glaser
Clifford Riebe
James Kirchner
Martha Conklin
Christina Tague
Elizabeth Boyer
Michael Goulden

Related Institutions/Organizations
University of California - Merced

Related Awards
#0725097 CZO: Critical Zone Observatory--Snowline Processes in the Southern Sierra Nevada

Total Grants
$5,853,286

Related Websites
NSF awards grants for four new critical zone observatories to study Earth surface processes: http://www.nsf.gov/news/news_summ.jsp?cntn_id=130115
NSF Publication: Discoveries in the Critical Zone: Where Life Meets Rock: http://www.nsf.gov/pubs/2013/nsf13112/nsf13112.pdf
NSF Critical Zone Observatories Network: http://criticalzone.org/national/
NSF Discovery Article: A Tree Stands in the Sierra Nevada: http://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=125091&org=NSF

Sierra Nevada forest of conifers
The western Sierra Nevada has extensive forests of conifers and other trees.
Credit and Larger Version

Researcher Jesse Hahm collects a tree core for forest productivity analysis.
Researcher Jesse Hahm collects a tree core for forest productivity analysis.
Credit and Larger Version

mountain with patchy forest cover,
Patchiness in forest cover, scientists have discovered, is explained by bedrock geochemistry.
Credit and Larger Version

Researcher  extracting a granite core
A granite core is extracted for geochemical analysis.
Credit and Larger Version

researcher with a gas-powered, water-cooled drill for sampling bedrock
Samples of bedrock are obtained using a gas-powered, water-cooled drill.
Credit and Larger Version



Email this pagePrint this page
Back to Top of page