Paper Info
Title
Using Reflectance Measurements to Determine Light use Efficiency in Corn
Abstract
Understanding the dynamics of the global carbon cycle requires an accurate determination of the spatial and temporal distribution of photosynthetic CO 2 uptake by terrestrial vegetation. Remote sensing observations may provide the spatially extensive observations required for this type of analysis acting as inputs to a light use efficiency model. These models describe increase in biomass, or gross ecosystem production (GEP) as the product of a photosynthetic efficiency term and absorbed photosynthetically active radiation (PAR), where absorbed PAR is the product of incident PAR and the fraction of PAR absorbed by vegetation (fAPAR). The light use efficiency (LUE) term changes over time in response to environmental factors such as soil moisture, air temperature, and vapor pressure deficit. Stress conditions may result in photosynthetic down-regulation of LUE and, in addition, have been shown to cause changes in the apparent spectral reflectance of leaves. This study examines the ability of narrow band vegetation indexes to detect these spectral changes and relate them to LUE over the course of a day as well as through the growing season. In a corn field in Beltsville, MD, carbon flux measurements were made at a flux tower using eddy covariance techniques. At this site on six days during the 2007 growing season hyperspectral reflectance measurements were collected at hourly intervals using a spectroradiometer attached to a transportable pole and moved along a 300-foot long transect. LUE was determined at the time of the reflectance measurements from carbon fluxes measured at the flux tower. The measured net ecosystem production (NEP) at the tower was partitioned into respiration and GEP, incident PAR was directly measured at the tower, and fAPAR was estimated using the Normalized Difference Vegetation Index (NDVI) from reflectance measurements. A number of spectral indices are studied, these indices have been shown to be related to a number of leaf characteristics including: the status of the xanthophyll cycle; solar induced
Year
DOI
Venue
2008
10.1109/IGARSS.2008.4779801
IGARSS
Keywords
Field
DocType
indexes,eddy covariance,vapor pressure deficit,production,sunlight,spectral reflectance,xanthophyll cycle,remote sensing,pigments,normalized difference vegetation index,growing season,stress,reflectivity,soil moisture,carbon,global carbon cycle,ecosystems,agriculture,air temperature,carotenoids,crops,data acquisition,vegetation
Xanthophyll,Sunlight,Growing season,Flux (metallurgy),Computer science,Remote sensing,Flux,Eddy covariance,Water content,Chlorophyll
Conference
Citations 
PageRank 
References 
1
0.76
0
Authors
7
Name
Order
Citations
PageRank
Karl Fred Huemmrich17317.23
Lawrence A. Corp23913.38
Andrew L. Russ352.77
Elizabeth M. Middleton49619.73
William P. Kustas55416.67
John H. Prueger66812.82
Yen-Ben Cheng7237.01