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, 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.
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.