Event Title

The Effects of Ultraviolet Radiation on Decomposition of Sagebrush Litter Collected Along an Altitudinal Gradient

Location

CSU Ballroom

Start Date

18-4-2016 10:00 AM

End Date

18-4-2016 11:30 AM

Student's Major

Biological Sciences

Student's College

Science, Engineering and Technology

Mentor's Name

Christopher Ruhland

Mentor's Department

Biological Sciences

Mentor's College

Science, Engineering and Technology

Description

A major contributor to the global carbon cycle is the decomposition of plant litter. Carbon dioxide released from decomposing organic material is an order of magnitude greater than that of fossil fuel combustion. Decomposition rates are typically dependent on climatic factors such as temperature and moisture as well as initial litter chemistry. However, the relative contribution of different wavelengths of radiation has only recently been examined and is not completely understood. The process of photodegradation involves the direct and indirect breakdown of plant litter components. Lignin, a major constituent of the secondary cell wall, has been implicated as a target for photodegradation. Lignin strongly absorbs ultraviolet radiation (“UV;” 280-400nm) and it is unknown if initial concentrations influence decomposition rates of plant litter. We collected leaves from a 1000-m altitudinal gradient in the Bighorn Mountains in Wyoming. Epidermal transmittance of UV increased from 12 to 20% along this gradient and there was a concomitant increase in concentrations of bulk- soluble UV-absorbing compounds. We hypothesized that litter from high elevations should photodegrade slower than their lower elevation counterparts due to increased UV-screening by these compounds. These leaves were then placed under lamps and exposed to 3.2 kJ m-2 d-1 of UV. We examined decomposition rates at 49, 183 and 310 days. Mass loss rates were negatively correlated with elevation and this relationship became more apparent over time. In arid ecosystems, it appears that UV levels should be taken into consideration when trying to model decomposition rates.

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Apr 18th, 10:00 AM Apr 18th, 11:30 AM

The Effects of Ultraviolet Radiation on Decomposition of Sagebrush Litter Collected Along an Altitudinal Gradient

CSU Ballroom

A major contributor to the global carbon cycle is the decomposition of plant litter. Carbon dioxide released from decomposing organic material is an order of magnitude greater than that of fossil fuel combustion. Decomposition rates are typically dependent on climatic factors such as temperature and moisture as well as initial litter chemistry. However, the relative contribution of different wavelengths of radiation has only recently been examined and is not completely understood. The process of photodegradation involves the direct and indirect breakdown of plant litter components. Lignin, a major constituent of the secondary cell wall, has been implicated as a target for photodegradation. Lignin strongly absorbs ultraviolet radiation (“UV;” 280-400nm) and it is unknown if initial concentrations influence decomposition rates of plant litter. We collected leaves from a 1000-m altitudinal gradient in the Bighorn Mountains in Wyoming. Epidermal transmittance of UV increased from 12 to 20% along this gradient and there was a concomitant increase in concentrations of bulk- soluble UV-absorbing compounds. We hypothesized that litter from high elevations should photodegrade slower than their lower elevation counterparts due to increased UV-screening by these compounds. These leaves were then placed under lamps and exposed to 3.2 kJ m-2 d-1 of UV. We examined decomposition rates at 49, 183 and 310 days. Mass loss rates were negatively correlated with elevation and this relationship became more apparent over time. In arid ecosystems, it appears that UV levels should be taken into consideration when trying to model decomposition rates.

Recommended Citation

Fraley, Philip. "The Effects of Ultraviolet Radiation on Decomposition of Sagebrush Litter Collected Along an Altitudinal Gradient." Undergraduate Research Symposium, Mankato, MN, April 18, 2016.
http://cornerstone.lib.mnsu.edu/urs/2016/poster-session-A/8