Featured Research

from universities, journals, and other organizations

Savanna vegetation predictions best done by continent

Date:
January 30, 2014
Source:
North Carolina State University
Summary:
A “one-size-fits-all” model to predict the effects of climate change on savanna vegetation isn’t as effective as examining individual savannas by continent, according to new research.

A single global model can’t predict savanna tree density as well as continent-specific models, according to research published in Science this week.
Credit: Dr. William Hoffmann

A "one-size-fits-all" model to predict the effects of climate change on savanna vegetation isn't as effective as examining individual savannas by continent, according to research published in Science this week.

Savannas -- grasslands dotted with trees -- cover about 20 percent of Earth's land and play a critical role in storing atmospheric carbon, says Dr. William Hoffmann, associate professor of plant and microbial biology at North Carolina State University and co-author of the study.

"We wanted to find out what controls savanna vegetation -- essentially the density of trees within the savanna -- and whether we can use a single global model to predict what will happen to savannas if global temperatures rise," Hoffmann said. "We found that the rules determining tree density are fundamentally different among the three continents studied -- Africa, Australia and South America. That means a 'one-size-fits-all' approach won't work."

The researchers examined more than 2,100 sites in savannas across the three continents. They found that tree density was influenced by a number of different factors, including moisture availability, temperature, soil fertility and frequency of fires. Yet the power of these relationships differed significantly among the three continents.

"For example, greater moisture availability -- a combination of rainfall, rainfall seasonality and drought indices -- meant greater tree density in Africa and Australia, but it had almost no relationship with tree density in South America," Hoffmann said.

Not surprisingly, he added, the study showed that fire reduces tree density.

But the researchers found some strong counter-intuitive relationships between rainfall and fire frequency, namely that more moisture meant more fires. Hoffmann explained that more rainfall in a savanna meant faster-growing grasses, which meant any fires in that savanna would have ample fuel to spread quickly and easily.

The researchers also modeled what would happen to tree density if the mean annual temperature increased by 4 degrees Celsius. Because tree density is controlled differently on the three continents, the study predicts different responses to global warming. In Africa, tree density is predicted to climb in hotter temperatures, while it is expected to decline in Australia and Africa. These differences, Hoffmann says, could not be predicted if savannas are assumed to behave identically across the tropics.

"Climate modelers examining atmospheric carbon dioxide levels use these types of models to make projections on carbon storage, which has major global implications," Hoffmann says. "We're trying to make these models better."

Caroline E.R. Lehmann of Macquarie University in Australia led the study. Researchers from some 20 universities around the globe contributed to the work.


Story Source:

The above story is based on materials provided by North Carolina State University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Caroline E. R. Lehmann, T. Michael Anderson, Mahesh Sankaran, Steven I. Higgins, Sally Archibald, William A. Hoffmann, Niall P. Hanan, Richard J. Williams, Roderick J. Fensham, Jeanine Felfili, Lindsay B. Hutley, Jayashree Ratnam, Jose San Jose, Ruben Montes, Don Franklin, Jeremy Russell-Smith, Casey M. Ryan, Giselda Durigan, Pierre Hiernaux, Ricardo Haidar, David M. J. S. Bowman, and William J. Bond. Savanna Vegetation-Fire-Climate Relationships Differ Among Continents. Science, 31 January 2014: 548-552 DOI: 10.1126/science.1247355

Cite This Page:

North Carolina State University. "Savanna vegetation predictions best done by continent." ScienceDaily. ScienceDaily, 30 January 2014. <www.sciencedaily.com/releases/2014/01/140130141219.htm>.
North Carolina State University. (2014, January 30). Savanna vegetation predictions best done by continent. ScienceDaily. Retrieved September 18, 2014 from www.sciencedaily.com/releases/2014/01/140130141219.htm
North Carolina State University. "Savanna vegetation predictions best done by continent." ScienceDaily. www.sciencedaily.com/releases/2014/01/140130141219.htm (accessed September 18, 2014).

Share This



More Plants & Animals News

Thursday, September 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Chimp Violence Study Renews Debate On Why They Kill

Chimp Violence Study Renews Debate On Why They Kill

Newsy (Sep. 17, 2014) The study weighs in on a debate over whether chimps are naturally violent or become that way due to human interference in the environment. Video provided by Newsy
Powered by NewsLook.com
Some Tobacco Farmers Thrive Amid Challenges

Some Tobacco Farmers Thrive Amid Challenges

AP (Sep. 16, 2014) The South's tobacco country is surviving, and even thriving in some cases, as demand overseas keeps growers in the fields of one of America's oldest cash crops. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Scientists Given Rare Glimpse of 350-Kilo Colossal Squid

Scientists Given Rare Glimpse of 350-Kilo Colossal Squid

AFP (Sep. 16, 2014) Scientists say a female colossal squid weighing an estimated 350 kilograms (770 lbs) and thought to be only the second intact specimen ever found was carrying eggs when discovered in the Antarctic. Duration: 00:47 Video provided by AFP
Powered by NewsLook.com
Raw: Scientists Examine Colossal Squid

Raw: Scientists Examine Colossal Squid

AP (Sep. 16, 2014) Squid experts in New Zealand thawed and examined an unusual catch on Tuesday: a colossal squid. It was captured in Antarctica's remote Ross Sea in December last year and has been frozen for eight months. (Sept. 16) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins