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WVU biology student uses Appalachian forests to improve future climate predictions

A West Virginia University student is using Appalachian forests to improve predictions of future climate change. 

Joe Carrara headshot
Joe Carrara

According to Joe Carrara, a Ph.D. candidate in the Department of Biology , research shows  humans have more than doubled the rate of nitrogen deposition on ecosystems across the world. Like carbon dioxide, nitrogen oxides are released into the atmosphere through the burning of fossil fuels, where they accumulate, react alongside sulfur containing molecules and eventually return to the Earth’s surface as acid rain.

Carrara is investigating the impact of increased levels of nitrogen deposition on forest ecosystems. This research could lead to a mechanism to improve future climate predictions.

This is important because of how uncertain the impact of added nitrogen will effect soils and ultimately the amount of carbon dioxide in the atmosphere,” Carrara said. “It matters because in the developing world, nitrogen deposition is skyrocketing.”

Due to the long history of coal burning power plants in the Ohio River Basin upwind from West Virginia, this region has experienced some of the highest rates of nitrogen deposition in the country.

To examine the impact of nitrogen deposition on soil carbon, Carrara used a long-term nitrogen fertilization experiment, the Fernow Experimental Forest, located in Parsons, West Virginia.

“We examined the relationships between trees, bacteria and fungi in a control watershed and a watershed that has been fertilized with nitrogen yearly since 1989,” Carrara said. “What we’ve found in West Virginia can be applied to forests around the world.”

The amount of carbon dioxide that remains in the atmosphere is ultimately driven by the balance between how much carbon dioxide trees take up through photosynthesis and how much is returned to the atmosphere through the respiration of living things, according to Carrara.  

“Soils are particularly important to this balance. Soils store more carbon than both the atmosphere and all vegetation combined,” Carrara said. “Bacteria and fungi that live in the soil decompose soil carbon, which they use for energy, and respire carbon dioxide into the atmosphere.”

Carrara’s research differs from others on climate change in that he found that decreases in soil carbon decomposition result from a weakening of the relationship between trees, soil bacteria and fungi, and the decomposition is not solely driven by decreases in fungal decomposition.  

“Ultimately, we find that trees allocate less carbon below ground, resulting in less root production and an increase in aboveground growth,” Carrara said. “This results in lower rates of carbon decomposition in the soil. This is important because any small change in the rate at which carbon dioxide is released back into the atmosphere from soil can have huge impacts on atmospheric carbon levels, and ultimately the temperature of the Earth.”

Carrara’s manuscript was recently published in Global Change Biology, a leading ecology journal.

“(Carrara) has been very successful here early on in his graduate career,” said Eddie Brzostek, assistant professor of forest ecology and ecosystem modeling. “In the beginning he received a prestigious graduate research fellowship from the National Science Foundation and has given talks at national and international conferences. Most recently, he has published this manuscript that is a huge accomplishment for a graduate student in their first two or three years of study.”