Research Highlights: September 2017

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The 2013 FLEX—US Airborne Campaign at the Parker Tract Loblolly Pine Plantation in North Carol

Elizabeth Middleton

(Biospheric Sciences Laboratory NASA GSFC)

Figure 1
Figure 2

A) The Fluorescence Ratio was highly correlated (r = 0.96) with the photosynthetic Light Use Efficiency (LUE) for AM/PM data () at the eddy covariance flux tower located in a large, uniform, mature loblolly stand, excluding midday data ().
Note: Midday observations are not useful for relating the Fluorescence Ratio to tower LUE.

B) Red fluorescence (F685) and the Photochemical Reflectance Index (PRI) were correlated when data from 30 stands were separated into "Young (2-12 year old) stands" and "established (20-33 year old) stands", both groups showing diurnal cycles with extreme values at midday: together describing the forest's stress level (Young ≠ Established).

Name: Elizabeth M. Middleton, Biospheric Sciences, NASA GSFC
Phone: 301-614-6670


Technical Description of Figures

Figure: Data were collected at the managed Parker Tract Loblolly Pine forest located near Plymouth, North Carolina, having multiple stands of varying age. The data were obtained with the HyPlant airborne system (PI: U. Rascher, Jülich Forschungszentrum): Fluorescence was derived from high spectral resolution measurements (≤ 0.3 nm) acquired with HyPlant's FLUO module, whereas hyperspectral reflectance measurements (≤ 5 nm) were made with HyPlant's DUAL spectrometer module. Stand heights and uniformity were confirmed using LiDAR data acquired simultaneously with the co-manifested G-LiHT airborne package (GSFC).

Key: (A)The tower flux data and airborne fluorescence data are separated into two temporal groups: midday () and combined morning and afternoon (). (B) Four times of day are shown for both young and established Loblolly Pine stands, where the arrows indicate the opposite direction of changing values in the morning and the afternoon.

Scientific significance, societal relevance, and relationships to future missions:

Together the red and far-red fluorescence (F685, F740) expressed as the Fratio were capable of describing tower LUE, except at midday when both GPP and incoming PAR were maximal. Both the PRI and F685 were necessary to describe forest stress over the diurnal cycle, and to distinguish young from mature stands.