Temporal Dynamics for Spectral Bio-Indicators and Photosynthetic Activities in a Cornfield
Elizabeth
Middleton, Biospheric Sciences, NASA/Goddard Space Flight Center, Greenbelt, MD, USA, elizabeth.m.middleton@nasa.gov
(Presenting)
Yen-Ben
Cheng, Biospheric Sciences, NASA/Goddard Space Flight Center, Greenbelt, MD, USA Lawrence
Corp, Biospheric Sciences, NASA/Goddard Space Flight Center, Greenbelt, MD, USA Karl
F.
Huemmrich, Biospheric Sciences, NASA/Goddard Space Flight Center, Greenbelt, MD, USA Petya
Campbell, Biospheric Sciences, NASA/Goddard Space Flight Center, Greenbelt, MD, USA Qingyuan
Zhang, Biospheric Sciences, NASA/Goddard Space Flight Center, Greenbelt, MD, USA William
Kustas, USDA/Agricultural Research Service, Beltsville, MD, USA Andrew
Russ, USDA/Agricultural Research Service, Beltsville, MD, USA
A collaborative field campaign was undertaken in an experimental USDA cornfield in Beltsville, MD to examine the temporal dynamics of spectral bio-indicators derived from canopy-level spectrometer observations and Earth Exploring One (EO-1) Hyperion satellite imaging spectrometer data. Diurnal measurements were conducted over six weeks in 2007 and over 14 weeks in 2008, across a transect within the footprint of an instrumented tower measuring carbon and energy fluxes. High resolution field spectroradiometers were used for canopy- and leaf-level measurements supported by biophysical data. In addition, a limited set of similar measurements, supplemented with infrared thermometer measurements, were obtained in 2009 in the established nitrogen treatment plots. For the transect data, we related spectral indices to the tower-derived photosynthetic light use efficiency (LUE = gross primary production / photosynthetically active radiation), focusing on LUE dynamics in conjunction with solar-induced chlorophyll fluorescence (SIF) and the Photochemical Reflectance Index (PRI), determined from 1 nm spectral resolution data. We found that canopy-level SIF, fluorescence yield (Fyield = SIF/PAR), and the PRI varied significantly throughout each field day, and that daily averages for each of these three parameters (PRI, SIF, and Fyield) declined linearly across the growing season as the cornfield progressed through vegetative and reproductive stages, and senescence. This seasonal change in 2008 was captured by SIF in the O2-B band (r2 = 0.93) and in the O2-A band (r2 = 0.87), and by the PRI (r2 = 0.88). In 2009, we found N treatment differences expressed in PRI, thermal, and Fyield values, with values associated with physiological stress obtained at the lower N treatment plots. From mid-summer 2008 Hyperion imagery, we found that two spectral indices calculated from derivative spectra, D730/D705 and ND705, generated significant correlations (r = 0.64, 0.48) to crop yield monitor data at harvest determined from a GIS-based yield map at 30-m spatial resolution over the entire experimental field. Our studies advocate the use of hyperspectral data with various bio-indicators to monitor, estimate and model vegetation physiological status and carbon-related activities.
Presentation Type: Poster
Poster Session: Carbon Cycle Science
NASA TE Funded Awards Represented:
Middleton, Elizabe
Spectral Bio-Indicators of Ecosystem Photosynthetic Efficiency II: Synthesis and Integration