Event Title

The Effects of Leaf Optics on Photodegradation of Artemisia tridentate Litter Sampled Along an Elevational Gradient

Location

CSU Ballroom

Start Date

20-4-2015 10:00 AM

End Date

20-4-2015 11:30 AM

Student's Major

Biological Sciences

Student's College

Science, Engineering and Technology

Mentor's Name

Christopher Ruhland

Mentor's Email Address

christopher.ruhland@mnsu.edu

Mentor's Department

Biological Sciences

Mentor's College

Science, Engineering and Technology

Description

Decomposition of plant litter is a key component in the global carbon cycle; it releases more carbon into the atmosphere than the combustion of fossil fuels annually. Photodegradation is the process in which solar radiation breaks down plant matter. The specific mechanism of this process is not yet fully understood. It has been hypothesized that litter from higher elevations should degrade faster as it is exposed to proportionally higher doses of ultraviolet radiation (“UV”). To test this hypothesis, leaf samples of _Artemisia tridentate_ (“sagebrush”) were collected at ten different altitudes along a 1000-m elevation gradient. Epidermal transmittance of UV decreased with elevation with values ranging from 20 to 12% along the ecocline. Leaf samples from ten plants at each elevation were then removed and returned to the lab where they are being irradiated under UV-A lamps at a biologicallyeffective dose of 3.19 kJ m-2 d-1. In addition we are measuring concentrations of UV-absorbing compounds in A. tridentate foliage to provide a proximate explanation for the epidermal transmittance. We hypothesize that litter from high elevations should photodegrade slower than their lower elevation counterparts due to increased UV-screening by these compounds. After the photodegrdation period is completed, samples will be massed and analyzed for concentrations of UV-absorbing compounds, cellulose, hemicellulose and lignin to provide explanations for mass loss. Our results should help elucidate how differences in leaf optical properties and composition along an elevation gradient influence photodegradation of plant matter.

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Apr 20th, 10:00 AM Apr 20th, 11:30 AM

The Effects of Leaf Optics on Photodegradation of Artemisia tridentate Litter Sampled Along an Elevational Gradient

CSU Ballroom

Decomposition of plant litter is a key component in the global carbon cycle; it releases more carbon into the atmosphere than the combustion of fossil fuels annually. Photodegradation is the process in which solar radiation breaks down plant matter. The specific mechanism of this process is not yet fully understood. It has been hypothesized that litter from higher elevations should degrade faster as it is exposed to proportionally higher doses of ultraviolet radiation (“UV”). To test this hypothesis, leaf samples of _Artemisia tridentate_ (“sagebrush”) were collected at ten different altitudes along a 1000-m elevation gradient. Epidermal transmittance of UV decreased with elevation with values ranging from 20 to 12% along the ecocline. Leaf samples from ten plants at each elevation were then removed and returned to the lab where they are being irradiated under UV-A lamps at a biologicallyeffective dose of 3.19 kJ m-2 d-1. In addition we are measuring concentrations of UV-absorbing compounds in A. tridentate foliage to provide a proximate explanation for the epidermal transmittance. We hypothesize that litter from high elevations should photodegrade slower than their lower elevation counterparts due to increased UV-screening by these compounds. After the photodegrdation period is completed, samples will be massed and analyzed for concentrations of UV-absorbing compounds, cellulose, hemicellulose and lignin to provide explanations for mass loss. Our results should help elucidate how differences in leaf optical properties and composition along an elevation gradient influence photodegradation of plant matter.

Recommended Citation

Fraley, Philip. "The Effects of Leaf Optics on Photodegradation of Artemisia tridentate Litter Sampled Along an Elevational Gradient." Undergraduate Research Symposium, Mankato, MN, April 20, 2015.
http://cornerstone.lib.mnsu.edu/urs/2015/poster_session_A/17