The National Ecological Observatory Network has invested in high-resolution airborne imaging of their field sites. 
Elevation models generated from LiDAR can be used to map the topography and vegetation structure at the sites.
This data gets really powerful when you can compare ecological processes across 
sites. 
Download the elevation models for the Harvard Forest (HARV) and San Joaquin Experimental Range (SJER) 
and the plot locations for each of these sites. 
Often, plots within a site are used as representative samples of the larger site 
and act as reference areas to obtain more detailed information and ensure 
accuracy of satellite imagery (i.e., ground truth).
SJER.raster math (chm = dsm - dtm) for SJER site.plot_locations folder.SJER and display the values.fun = max) in a buffer of 10 for each point at the HARV site and SJER plots. Create a single dataframe with two columns, one holding the maximum height values for each site at each plot_id.