Subsets the information on long term ecological research (LTER) sites based on user-specified site codes (i.e., three letter abbreviations), and/or desired habitats. See lter_sites
for the full set of site information
site_subset(sites = NULL, habitats = NULL)
(dataframe) complete site information (8 columns) for all sites that meet the provided site code and/or habitat criteria
(character) three letter site code(s) identifying site(s) of interest
(character) habitat(s) of interest. See unique(lter_sites$habitat)