## Results
### Data Collections at High Spatial or Stand Level Resolution
#### 3.1.2. Canopy Structure  
The stand canopy heights were determined using the G-LiHT LiDAR Canopy Height Module (CHM) data (2 m), averaged over several overpasses of the Parker Tract study site. Based on their average CHM values (for each of the 30 ROI cutouts), the LP stands were assigned to one of three height categories: low (\(\leq\)9 m with open canopy, LP low), medium (10-20 m with a dense closed canopy, LP Med), and high (\(\leq\)27 m with closed canopy, NC2 Tower) (Figure 4), which was verified with point measurements of tree height, DBH, canopy LAI, and density. Figure 4A,B provides examples of the 120 m \(\times\) 120 m ROI cutouts within representative stands for the 3 height categories, with the mean \(\pm\) SD (and maximum/minimum values) per category. A side view of the geo-referenced point cloud is provided in Figure 4C, where first returns from tree crowns (@ 2 m) were processed through  
Figure 3: NC2 flux tower data at Parker Tract throughout 2013 (**A**,**C**,**E**) and October 2013 (**B**,**D**,**F**). GEP (\(\mu\)mol CO\({}_{2}\) m\({}^{-2}\) s\({}^{-1}\)): (**A**) average daily values throughout 2013; and (**B**) half hour values for the six days that include the campaign days. Incident PAR (\(\mu\)mol PARi m\({}^{-2}\) s\({}^{-1}\)): (**C**) average daily values throughout 2013; and (**D**) for half hour values for six days that include the two campaign days, 26 October 2013. Light Use Efficiency, LUE (\(\mu\)mol CO\({}_{2}\)\(\mu\)mol\({}^{-1}\) photons): (**E**) the daily averages throughout 2013; and (**F**) half hour values for the six days that included the campaign days.  
the CHM (yellow layer) and the ground-level returns (blue layer) were determined with a Digital Terrain Model, DTM. Other LiDAR information that is computed includes surface rugosity (SD of CHM @ 2m), tree fractional cover (14 m), and the distribution of canopy elements (Deciles & Percentiles @ 14 m). Also shown in Figure 4D is a graphic example of the fine scale co-registration of G-LiHT's data products, where the RGB optical image of the Duke Forest study site is overlaid on the LiDAR digital elevation product.  
We note that FLUO data acquired in this campaign provided critical information that led to corrections for instrument signal effects that affected the usage of the highest resolution (2 m) data, subsequently rectified by the manufacturer (Specim, Inc., Oulu, Finland).  
The ROI cutouts were separately analyzed at the 14 m\({}^{2}\) spatial resolution described by the G-LIHT data products, from which a relationship between canopy height, stand age, and red fluorescence was successfully developed and reported elsewhere by [PERSON] et al. (2014).  
Figure 4: Various G-LiHT LiDAR data products. (**A**) CHM data for 120 m \(\times\) 120 m ROIs for 3 height categories within the Parker Tract study area (LP low, LP Med, LP High at NC2 Tower); (**B**) Bar chart describing the mean CHM \(\pm\) SD (and minimum, maximum values) for the three height categories (\(n\) = 30 ROI); (**C**) Side View of a LiDAR Geo-referenced Point Cloud collected at 2 m, where first returns from tree crowns were processed through the CHM (yellow layer); the ground-level returns (blue layer) were determined with a Digital Terrain Model, DTM. The top of the flux tower is seen in the background; (**D**) 3-D site mosaic produced with CHM data overlaid on a G-LiHT RGB reflectance image from the VNIR spectrometer, which accentuates the variation in canopy heights across the site. The middle and bottom examples are from Duke Forest, NC.