Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Agriculture expansion could reduce rainfall in Brazil's Cerrado

01.04.2016

Agricultural expansion is quickly chewing up native vegetation in the vast wooded savannas of Brazil's Cerrado biome, and a new study shows that those changes in land use are altering the region's water cycle.

"We've shown that cropland recycles less water annually back into the atmosphere than native Cerrado vegetation," said Stephanie Spera, a graduate student at Brown University in the department of Earth, Environmental and Planetary Science and a researcher at the Institute at Brown for Environment and Society (IBES). "As agriculture continues to expand, that could affect the rainfall regime that supports both natural vegetation and agricultural production."


Satellite images show that agricultural land use in a key region of Brazil's Cerrado doubled in a decade. That expansion is altering the region's water cycle, a new study finds.

Credit: NASA / Mustard Lab / Brown Unviersity

The study, which Spera led along with researchers from the University of Vermont and the Woods Hole Research Center, is published in the journal Global Change Biology.

While the Brazilian Amazon has been the focus of intense conservation efforts, the neighboring Cerrado has received much less attention, Spera said. As a result, deforestation to make room for cropland has increased in the Cerrado, even as it has slowed significantly in the Amazon.

Spera and her colleagues used a decade's worth of satellite data to document those land use changes in a Cerrado region called Matopiba, where a bulk of recent agricultural expansion has taken place. The data showed that agricultural land more than doubled in area, from 1.3 million hectares in 2003 to 2.5 million hectares in 2013, within the 45 million-hectare study area. Nearly three quarters of that expansion happened on land that had been host to intact native Cerrado vegetation.

The researchers also used the satellite data to estimate the region's rate of evapotranspiration -- the amount of water escaping soil and plant leaves that is recycled back into the atmosphere. The data showed that during the growing season, cropland recycles as much or slightly more water than native vegetation. But during the dry season, when the fields are fallow, evapotranspiration from agricultural land was an average of 60 percent lower than from native vegetation.

As cropland continues to expand at the expense of Cerrado vegetation, the decrease in dry season water recycling could eventually impact the region's critical rainy season, which is responsible for the lion's share of Cerrado rains. "Modeling studies have shown that alteration of the regional water cycle during the dry season could affect both the timing and stability of the rainy season," Spera said.

That has implications for both the natural vegetation and the continued viability of the region for agricultural production.

"Timing of rains is a big deal," said Jack Mustard, a professor of earth, environmental and planetary sciences at Brown and co-author on the study. "This is nearly all rain-fed agriculture in this region. If you start delaying the onset of the rainfall, that has implications for what you can grow."

But the impacts aren't necessarily confined to the Cerrado. Prevailing winds carry Cerrado air masses westward toward the Amazon, and the moisture within them contributes to rainfall there as well.

"Half of the rainfall in the Amazon is recycled water," Spera said. "So a decrease in moisture in those air masses could cause a decrease in rainfall."

The study also, however, identified a potential mitigating factor to the overall decrease in water recycling: double cropping.

Double cropping is the planting of two crops in the same field in a single growing season. The study showed that, in terms of annual evapotranspiration, double-cropped land behaves more similarly to native vegetation. That's because double cropping effectively increases the length of the active growing season -- the period during which cropland evapotranspiration rivals that of native vegetation.

Double cropping increased from just 2 percent of cropland in 2003 to more than 26 percent in 2013. Without that increase in double cropping, the reduction of water recycling in croplands would have been as much as 25 percent worse, the study showed.

The researchers suggest that policies that encourage double cropping could help to blunt the effect of agricultural expansion on the Cerrado water cycle.

###

Other authors on the study were Gillian Galford (University of Vermont), Michael Coe (Woods Hole) and Marcia N. Macedo (Woods Hole). The work was funded by the NASA Land-Cover/Land-Use Change Program (NNX11AH91G and NNX11AE56G), a NASA Terrestrial Ecology grant (NNX12AK11G), and the Gordon and Betty Moore Foundation and a IBES fellowship.

Kevin Stacey | EurekAlert!

More articles from Earth Sciences:

nachricht Massive impact crater from a kilometer-wide iron meteorite discovered in Greenland
15.11.2018 | Faculty of Science - University of Copenhagen

nachricht The unintended consequences of dams and reservoirs
14.11.2018 | Uppsala University

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Purdue cancer identity technology makes it easier to find a tumor's 'address'

16.11.2018 | Health and Medicine

Good preparation is half the digestion

16.11.2018 | Life Sciences

Microscope measures muscle weakness

16.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>