## 5 Conclusions  
This study demonstrates the importance of diurnal observations for interpretation of fluorescence dynamics, as well as the utility of the red fluorescence for understanding canopy physiological processes, especially since red fluorescence responses were strongly affected by diurnal temperature differences and Loblolly pine stand age. The benefit of simultaneously acquiring fluorescence, high spectral resolution full-spectrum reflectance, and LiDAR observations from aircraft was demonstrated for describing vegetation structure, biochemical constituents, and physiological stress responses to the environmental conditions, at ecologically relevant (15-50 m) spatial scales during early fall senescence. In particular, the combination of the red fluorescence, the red/far-red Fratio, and the PRI together provide insight about canopy diurnal physiological dynamics, especially those driven by the canopy light regime and temperature. The Fratio obtained for the mature Loblolly pine stand at the NC2 tower site was strongly related to canopy LUE. The difficulty of estimating canopy carbon uptake using remote sensing acquisitions obtained at/around solar noon when both the spectral and flux data were nearly constant, versus measurements acquired under changing mid-morning and afternoon time periods, was demonstrated. We note that whereas the combination of LiDAR CHM with VSWIR spectra provided the optimal LP stand age class map, the VSWIR spectra alone discriminated these age classes quite well. This is useful information for the future FLEX satellite, which in tandem with Sentinel-3 will collect wavelengths (but not continuous spectra) across the VSWIR spectrum. This capability could be ensured if FLEX and the NASA HypIRI mission, which will collect VSWIR spectra, were flown during the same years. We note that our study reveals the importance of quantifying the diurnal fluorescence dynamics related to irradiance and thermal influences on canopy physiology, which will likely be addressed through modeling of these responses. However, much more needs to be learned about the diurnal expression of these responses, including variability across plant types, and their expression throughout the annual cycle. We recommend that additional airborne campaigns utilizing a similar suite of instruments be conducted during summertime at peak production and throughout the growing season over other well-characterized study sites, especially fruitful when paired with a flux tower, to complement and reinforce the findings of this unique experiment conducted during fall senescence in a managed pine forest. **Acknowledgments: Funding for FLEX-US 2013 was provided by the European Space Agency (ESA Contract No. 4000109199/13/NL/FF/If), NASA HQ ([PERSON]), and NASA/GSFC (Code 610). The development of HypPlant was supported by the large scale investment grant of the Forschungszentrum Julich, Germany. Further support for campaign activities was provided by the SFB/TR 32 \"Patterns in Soil-Vegetation-Atmosphere Systems: Monitoring, Modelling, and Data Assimilation\"--subproject D2 (www.tr32.de), funded by the Deutsche Forschungsgemeinschaft (DFG), Germany. The work at the Parker Tract, NC (US-NC2) site was supported by USDA Forest Service Eastern Forest Environmental Threat Assessment Center Cooperative Agreements 03-CA-11330147-073 and 04-CA-11330147-238, DOE-National Institute for Climate Change Research (NICCR) Award 08-SC-NICCR-1072, Department of the Interior (DOI) Southeast Climate Science Center Award G10 AC00624, DOE Terrestrial Ecosystem Science Award 11-DE-SC-0006700, and USDA NIFA Awards 2011-68002-30185 and 2014-67003-22068. The FLEX-US team gratefully acknowledges the roles of [PERSON] (USDA Forest Service (FS), Eastern Forest Environmental Threat Assessment Center, Raleigh, NC, USA) and [PERSON] (USDA Forest Service, South-Eastern Regional Climate Hub, Raleigh, NC, USA) in providing funding and other support of the US-NC2 site, including ancillary modeling research. We also thank Drs. [PERSON] and [PERSON] (Dept. Environ.