This function calculates summary statistics for vegetation plots grouped by vegplotiid, specifically:
total_records - the total number of records associated with each vegplotiid
unique_species - The number of unique species recorded for each vegplotiid.
percent_to_species - the percentage of observations identified to the species level (determined by the presence of a space in plantsciname).
percent_with_abund - the percentage of observations with a non-NA value in the pct_cover column.