Effects of diffuse photosynthetically active radiation on light use efficiency of salt marsh species

Authors: Peter Hawman*, , Deepak R Mishra, University of Georgia, David L Cotten, University of Georgia, Jessica L O'Connell, University of Georgia
Topics: Marine and Coastal Resources, Remote Sensing
Keywords: remote sensing, salt marsh, coastal ecosystem, eddy covariance, PAR, photosynthesis, light use efficiency
Session Type: Paper
Day: 4/14/2018
Start / End Time: 8:00 AM / 9:40 AM
Room: Napoleon A2, Sheraton, 3rd Floor
Presentation File: No File Uploaded


Photosynthetically active radiation (PAR) is the portion of the electromagnetic spectrum utilized by plants for photosynthesis ranging from 400 to 700 nm. Past research has shown varying responses to ratios of diffuse and direct PAR on photosynthetic rates for different terrestrial plant communities, but little is known of its effects on coastal wetland species. Known as apparent quantum yield, the linear portion of the light response curve representing the ratio of CO2 fixed to PAR absorbed provides a quantification of canopy level light use efficiency (LUE). This study aimed to determine how coastal wetland species' light use efficiency responds to varying ratios of diffuse PAR. Eddy Covariance flux data along with accompanying meteorological data were collected for two coastal salt marsh species, Spartina alterniflora and Juncus roemerianus which dominate salt and brackish marshes within the southeastern United States. Results indicated that although gross primary production (GPP) was lower during high ratios of diffuse PAR, the canopy level quantum yield was higher than when diffuse PAR ratios were low. These results indicate light use efficiency may increase when the atmosphere is dominated by diffuse PAR.

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