Photodegradation has been recognized as a contributor to litter decomposition in a wide variety of ecosystems, however many of the mechanisms that drive it remain unknown. The primary focus of this study was to investigate the effect of surface albedo on the rate at which plant litter photodegrades. The first hypothesis that was tested was that surfaces with higher albedo will increase the rate of mass loss. The second hypothesis was that a wild type Sorghum bicolor with higher lignin concentration will degrade more rapidly than a double mutant variety. Three different artificial surface covers (aluminum foil, black paint, and white paint) were used to mimic the surface albedo of natural surfaces. Two varieties of Sorghum bicolor (wild type (WT) & double mutant (DM)) that differed in initial litter chemistry were placed on the surfaces and exposed to varying levels of solar radiation for 200-d. Mass loss, cell wall constituent (hemicellulose, cellulose and lignin) concentrations and bulk-soluble phenolic concentrations were examined every 50-d, for the duration of the experiment. In support of our first hypothesis, decomposition of the WT and DM litter was generally faster on the aluminum surfaces than on the black and white surfaces. Litter collected from the aluminum surfaces lost an average of 1.71% more mass than the black surfaces and an average of 3.08% more mass than the white surfaces. In contrast to our second hypothesis, the higher lignin, WT litter, photodegraded at a slower rate than did the lower lignin, DM litter. Following the 200-d collection, DM litter lost approximately 5% more mass, with WT losing an average of 47.5% of initial mass, and DM losing an average of 52.6% across all surface types.
Date of Degree
Master of Science (MS)
Science, Engineering and Technology
Niere, Joshua, "The Effects of Surface Albedo and Initial Lignin Concentration on Photodegradation of Sorghum Bicolor Litter" (2018). All Theses, Dissertations, and Other Capstone Projects. 823.
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Available for download on Tuesday, August 27, 2019