Navigation Links
Why juniper trees can live on less water
Date:2/27/2008

DURHAM, N.C. -- An ability to avoid the plant equivalent of vapor lock and a favorable evolutionary history may explain the unusual drought resistance of junipers, some varieties of which are now spreading rapidly in water-starved regions of the western United States, a Duke University study has found.

"The take-home message is that junipers are the most drought-resistant group that has ever been studied," said Robert Jackson, a professor of global environmental change and biology at Duke's Nicholas School of the Environment and Earth Sciences.

"We examined 14 species from the U.S. and Caribbean, and they're all relatively drought-resistant -- even ones in the mountains of Jamaica that get hundreds of inches of rain a year," he said.

"They've been expanding for about 100 years in some places, and drought plays a role in that," added Jackson, who is corresponding author of the new report published Feb. 27 in the American Journal of Botany's online edition. "For example, recent droughts have decimated pinyon pine populations in pinyon-juniper woodlands of the Southwestern U.S. but left the junipers relatively unscathed."

Many juniper species -- including several popularly known as cedars -- "are invading drier habitats and increasing in abundance where they already exist by surviving droughts that other conifers cannot," the report said.

The work was funded by the National Science Foundation, Duke University and the Andrew W. Mellon Foundation.

To understand why junipers are so successful, Jackson's graduate student Cynthia Willson and Duke associate biology professor Paul Manos assessed structural and genetic features in the 14 species that can explain their special drought tolerance.

They found a key structural adaptation in junipers: resistance to what scientists call "cavitation" -- a tendency for bubbles to form in the water-conducting xylem tissues of plants.

Water is sucked through xylem tissues under a partial vacuum, "so it's almost like a rubber band being stretched out," explained Jackson. "The dryer the conditions, the greater the tension on that 'rubber band' and the more likely that it will snap. If it snaps, air bubbles can get into the xylem."

The scientists found that xylem tissues of juniper species tend to be reinforced with extra woody material to prevent rupture. Such rupturing can introduce bubble-forming air either through seepage from adjacent cavities or by coming out of solution from the water itself, Jackson said.

The scientists also determined that the more cavitation-resistant Juniper species have thicker but narrower leaves -- a trait known as low specific leaf area (SLA) -- and live primarily in the western United States.

"Plants in drier environments typically have lower SLA," said Willson, the study's first author, who having completed her Ph.D. at Duke is now a student at North Carolina State University's College of Veterinary Medicine. "We found that junipers from the driest environments were more drought resistant and also had the lowest SLA."

Their research found that the most cavitation-resistant species is the California juniper, which grows in California's Mojave Desert, while the least resistant is the eastern red cedar -- the most widespread conifer in the relatively-moist eastern U.S.

While less drought-tolerant than other junipers, eastern red cedars still handle dry spells well and are in fact invading into Midwestern states including Nebraska, Jackson noted. Juniper species growing in wet parts of the Caribbean also benefit from drought tolerance because they "tend to grow in shallow, rocky soils that don't hold a lot of water," Jackson said.

In parts of the Southwest undergoing an extended drying period, junipers are edging out another hardy, water-thrifty conifer -- the pinyon pine. "They're both very drought- resistant, but the pinyons aren't as resistant as the junipers are," Jackson said.

The scientists also investigated how and where these tree types evolved their collective drought tolerance by analyzing each juniper species' DNA. That analysis found that junipers evolved into different species relatively recently, separating into eastern and western groups -- technically called "clades."

"The center of diversity for junipers is in arid regions of Mexico," said Willson. "The fact that many juniper species seem to be more drought-resistant than necessary for their current range suggests that a common ancestor of those two clades was also quite drought-resistant."


'/>"/>
Contact: Monte Basgall
monte.basgall@duke.edu
919-681-8057
Duke University
Source:Eurekalert

Related biology news :

1. Fighting pollution the poplar way: Trees to clean up Indiana site
2. Climate change predicted to drive trees northward
3. Canada provides $1.4M for removal of hazardous trees from provincial recreation sites
4. Exeter scientists pour cold water on EU bird policy
5. Bacteria and nanofilters -- the future of clean water technology
6. Salamanders, headwater streams critical in food chain
7. Unveiling the underwater ways of the white shark
8. Ecological genetics of freshwater bacteria surveyed
9. ASU professor helps solve mystery of glassy water
10. River plants may play major role in health of ocean coastal waters
11. Generalist bacteria discovered in coastal waters may be more flexible than known before
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:4/11/2017)... , April 11, 2017 No two ... researchers at the New York University Tandon School ... Engineering have found that partial similarities between prints ... used in mobile phones and other electronic devices ... The vulnerability lies in the fact that ...
(Date:4/5/2017)... 4, 2017 KEY FINDINGS The ... at a CAGR of 25.76% during the forecast period ... primary factor for the growth of the stem cell ... MARKET INSIGHTS The global stem cell market ... and geography. The stem cell market of the product ...
(Date:3/30/2017)... Trends, opportunities and forecast in this market ... (fingerprint, AFIS, iris recognition, facial recognition, hand geometry, vein ... use industry (government and law enforcement, commercial and retail, ... others), and by region ( North America ... Pacific , and the Rest of the World) ...
Breaking Biology News(10 mins):
(Date:7/18/2017)... ... July 18, 2017 , ... Genedata, a leading provider of ... technology company, has implemented Genedata Biologics ™ to scale-up their bispecific antibody ... and Neurodegenerative Diseases. , The need to systematically evaluate large panels of ...
(Date:7/18/2017)... ... July 18, 2017 , ... Allotrope Foundation won the ... phase of the Allotrope Framework for commercial use. , The Bio-IT World Best ... only elevate the critical role of information technology in modern biomedical research, but ...
(Date:7/17/2017)... ... , ... The Academy of Model Aeronautics (AMA) will host Aviation Adventure Day ... place from 9 a.m. to 2 p.m. at the International Aeromodeling Center in Muncie, ... Adventure Day will be packed with entertaining activities for the entire family. Attendees will ...
(Date:7/17/2017)... ... July 17, 2017 , ... Neurodevelopmental disorders (NDDs) ... of overlapping clinical features. The advancement of targeted next-generation sequencing (NGS) has been ... and testing. , However, designing a custom panel for disease research requires ...
Breaking Biology Technology: