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 Impacts of mass coral die-off on Indian Ocean reefs revealed
21.02.2017 | University of Exeter

nachricht How much biomass grows in the savannah?
16.02.2017 | Friedrich-Schiller-Universität Jena

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Impacts of mass coral die-off on Indian Ocean reefs revealed

21.02.2017 | Earth Sciences

Novel breast tomosynthesis technique reduces screening recall rate

21.02.2017 | Medical Engineering

Use your Voice – and Smart Homes will “LISTEN”

21.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>