February 22, 2012

Soil May Be Clue To Climate Change

Looking for answers to the problem of climate change and what might cause it, a Texas A&M University student researcher believes some clues might be found in soil.

Justin Whisenant looking at a loblolly pine forest from a bridge

Justin Whisenant

Justin Whisenant, a senior from College Station with a double major in forest management and spatial science, believes specific soil experiments could reveal answers about the causes of climate change. His work has been published in Explorations, a journal detailing undergraduate research at Texas A&M.

Whisenant says carbon dioxide is generally accepted as the cause of rising global temperatures and will likely be a contributor in the years to come.

“Carbon on Earth is not static. It cycles between the atmosphere, plants, the ocean and the soil,” he contends.

“Many factors complicate the movement of carbon between these systems. Some of these factors, such as fertilization and nitrogen deposits from air pollution, are caused by human activity, so understanding them can help direct decision makers with efforts to mitigate climate change.”

Whisenant says forest ecosystems tend to collect large amounts of carbon, so understanding the dynamics of soil in these regions is a good starting point.

“In most forests, stored carbon actually exists in the soil, not above ground,” he notes. “Globally, soils store twice as much carbon as aboveground biomass.”

Whisenant says roots, limbs and leaves all collect on the forest floor, with much of their stored carbon remaining in the soil. Carbon returns to the atmosphere as soil microbes decompose the organic matter.

A microbial respiration measurement station recorded the data

Microbial respiration measurement station used to test soil samples

Using a device called a microbial respiration measurement station, Whisenant performed tests on soil samples collected from a loblolly pine forest in Florida, trying to assess how much microbial respiration responded to various amounts of nitrogen and phosphorus, two commonly found ingredients in fertilizer.

After two months of tests, the results showed that the nitrogen and phosphorus suppress soil respiration independently of root effects — nitrogen’s suppressive effects were stronger than those of phosphorous.

“We can infer from these results that commonly used management strategies of forests can be a worthwhile contribution to mitigate climate change,” Whisenant explains.

“The results show that some management practices that increase tree carbon storage also increase soil carbon storage. Forested lands take on even greater significance when we understand their positive effects in combating climate change.”

Since many forests near urban areas receive nitrogen from industrial and transportation emissions, “these additions are much more widespread than forest fertilization and could affect microbial respiration,” he adds.

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About Research at Texas A&M University: As one of the world’s leading research institutions, Texas A&M is in the vanguard in making significant contributions to the storehouse of knowledge, including that of science and technology. Research conducted at Texas A&M represents an annual investment of more than $630 million, which ranks third nationally for universities without a medical school, and underwrites approximately 3,500 sponsored projects. That research creates new knowledge that provides basic, fundamental and applied contributions resulting in many cases in economic benefits to the state, nation and world.

Media contact:  Keith Randall, News & Information Services, at (979) 845-4644 or Justin Whisenant at (979) 229-3703

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