Friday, January 04, 2008

Model the possible effects of biofuels crops

South Dakota research is looking at possible environmental changes that could accompany a shift toward new biofuel crops such as perennial grasses.

The National Aeronautics and Space Administration (NASA) is funding a $738,000 three-year study by South Dakota State University, the South Dakota School of Mines & Technology, and the U.S. Geological Survey’s EROS Data Center through the Experimental Program to Stimulate Competitive Research (EPSCoR).

“We want to investigate some of the potential impacts of widespread cultivation of biofuel feedstock crops on regional weather as well as regional wildfire risk,” said SDSU professor Geoff Henebry, a senior scientist in the Geographic Information Science Center of Excellence (GIScCE) at SDSU.

In addition to the GIScCE, the SDSU departments involved in the project include Biology/Microbiology, Plant Science, Agricultural and Biosystems Engineering, and Geography.

Henebry, the project’s principal investigator, said the research also helps evaluate a new model of actual evapotranspiration developed by Gabriel Senay, a remote sensing scientist and agricultural engineer at the U.S. Geological Survey’s Center for Earth Resources Observation and Sciences (EROS). Senay is also a senior scientist and adjunct professor at the GIScCE, a joint collaboration between SDSU and EROS.

“Evapotranspiration” measures both the evaporation from plant or soil surfaces and the transpiration or movement of water within the plant from the root zone out through the leaves.

The project focuses on South Dakota, North Dakota, Nebraska, western Minnesota, and northwestern Iowa.

“Part of the interest in this model is if we have a widespread change in cropping patterns — say we go to far more corn-corn rotations, or we have widespread adoption of switchgrass as a biofuel feedstock crop — how might that impact the seasonal cycle of water and energy exchanges between the land surface and the atmosphere?” Henebry said. “In the typical season, perennial grasses are going to have high water use much earlier in the season than the corn crops or the soybean crops.”

Henebry said there has been emphasis through the Sun Grant Initiative on the agronomic and technological aspects of growing and processing biofuels crops. The new study would look at some indirect effects that could accompany biofuels crop production.

“It’s something we think is important to investigate because it has potential consequences in possibly changing the regional weather patterns,” Henebry said, adding that it’s too soon to speculate how regional weather could change.

Fires were common in the Great Plains for thousands of years before European settlement, but wildfire is not a major concern in today’s agriculture-dominated landscapes, said SDSU research scientist Michael Wimberly, an associate professor in the GIScCE.

“This situation might change, however, if increased cultivation of switchgrass or similar crops results in landscapes dominated by highly flammable fuelbeds. A prospective study like ours offers an opportunity to assess the potential for this type of unintended and unexpected consequence,” Wimberly said.

“It’s a very complex system. We do not anticipate having widespread changes throughout the region. Because biofuels feedstocks are bulky, you want to minimize transportation costs. So it makes the most sense to be growing crops around ethanol plants. There are certainly lots of ethanol plants built, under construction, and planned. So you can imagine ‘patchy’ kinds of changes.”

The research builds on SDSU’s expertise in research with satellite imagery.

“We can’t see the future with the satellite images. We can use models to be able to investigate what possible futures may be through scenario generation and evaluation,” Henebry said. “What we’re doing is taking some contemporary models and tuning them, calibrating them, and validating them on our current land surface in conjunction with field data, and then taking those tuned models and introducing a new land cover – one that we may see in the next few decades – to see what the responses are in terms of regional weather and aspects of the water cycle.”

The study also will use data from carbon flux towers to help calibrate and validate remote sensing data, specifically in regard to evapotranspiration. Carbon flux towers gather detailed information about carbon dioxide captured via photosynthesis, carbon dioxide emitted via respiration, and water vapor changes from within a small area compared to satellite observations.

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