Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Drought and fire in the Amazon lead to sharp increases in forest tree mortality

17.04.2014

Ongoing deforestation and fragmentation of forests in the Amazon help create tinderbox conditions for wildfires in remnant forests, contributing to rapid and widespread forest loss during drought years, according to a team of researchers.

The findings show that forests in the Amazon could reach a "tipping point" when severe droughts coupled with forest fires lead to large-scale loss of trees, making recovery more difficult, said Jennifer Balch, assistant professor of geography, Penn State.


This is a thousand-hectare burn in the southeastern Amazon, that was lit to remove unwanted trees to make way for agriculture, escaped into the adjacent forest.

Credit: J.K. Balch, 2004.

"We documented one of the highest tree mortality rates witnessed in Amazon forests," Balch said. "Over the course of our experiment, 60 percent of the trees died with combined drought and repeated fire. Our results suggest that a perfect firestorm, caused by drought conditions and previous fire disturbance, crossed a threshold in forest resistance."

Balch noted that climate change is expected to warm the air in the Amazon region by several degrees and substantially reduce regional precipitation, making understanding the interactions between droughts and fires even more important. "However, even before any prediction of Amazon climate warming occurs, our study demonstrates that drought and fire are already driving forest dieback," she said.

... more about:
»Administration »Amazon »Earth »NASA »atmosphere »landscape

The eight-year study is the largest and longest-running fire experiment in tropical forests. The team of researchers burned 50-hectare forest plots in the southeastern Amazon, a region prone to the effects of climate change.

The plots were burned every year, every three years or not at all. The timeframe for the study included 2007, a year of severe drought. By comparing the tree deaths for the plots each year, the researchers could assess the effect of drought on fire intensity and tree deaths.

"Drought causes more intense and widespread fires," said lead author Paulo Brando, Instituto de Pesquisa Ambiental da Amazônia, Carnegie Institution for Science and Woods Hole Research Center. "Four times more adult trees were killed by fire during a drought year, which means that there was also more carbon dioxide released to the atmosphere, more tree species loss and a greater likelihood of grasses invading the forest."

The researchers found that fragmented forests are more susceptible to the negative impacts of drought and fire and that drought leads to an increase in fuel such as leaves and branches. The findings are key, in part, because most climate change models have not included the impacts of fires on Amazonian forests.

"Basically, none of the models used to evaluate future Amazon forest health include fire, so most of these predictions grossly underestimate the amount of tree death and overestimate overall forest health," said Michael Coe, Woods Hole Research Center.

Fire as a forest management tool can contribute to an increase in severe fires because the resulting thinner canopy leads to dryer forest conditions. This lack of humidity does not dampen fires but does encourage airflow between fields and forests. Fragmented forests also have more edge space, which is susceptible to both fire and invasive grasses -- another potential fuel.

"These forests are tough and can take a lot, but if drought reaches a certain level, big trees begin to die," said Daniel Nepstad, Earth Innovation Institute, who also co-led the study. "We now know that severe drought also makes fires more intense, creating a second tree mortality threshold."

The researchers conclude in today's (April 14) issue of Proceedings of the National Academy of Science that "efforts to end deforestation in the Amazon must be accompanied by programs and policies that reduce the accidental spread of land management fires into neighboring forests and effectively control forest fires when started."

The results are important because large portions of the Amazon forest already experience droughts and are susceptible to fire -- they are broken into smaller blocks by agriculture and they are close to humans, who are the predominant source of fire in the Amazon. The researchers analyzed NASA satellite data to provide regional context for results from the experimental burns.

"In 2007, fires in Southeast Amazonia burned 10 times more forest than in an average climate year -- an area equivalent to a million soccer fields," said Douglas Morton, NASA.

"These smaller forest fragments have more edges than large blocks of forest, which exposes them to the hotter, dryer conditions in the surrounding landscape and makes them more vulnerable to escaped fires," said co-author Marcia Macedo, Woods Hole Research Center.

By 2011, around 8 percent of Southeast Amazonia's forests were less than 328 feet from an agricultural or pasture clearing. This lattice-like network of degraded forest edges is now extremely susceptible to future fire.

###

The National Science Foundation, Packard Foundation, National Aeronautics and Space Administration, and Max Planck Institute for Biogeochemistry supported this research.

A'ndrea Elyse Messer | Eurek Alert!
Further information:
http://www.psu.edu

Further reports about: Administration Amazon Earth NASA atmosphere landscape

More articles from Ecology, The Environment and Conservation:

nachricht Successful calculation of human and natural influence on cloud formation
04.11.2016 | Goethe-Universität Frankfurt am Main

nachricht Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>