Played on Baritone ukulele.
Tuning (low to high): Db Gb Bb Eb
Joni tuning: Db545

(Or use guitar with all strings tuned one semitone down to Eb Ab Db Gb Bb Eb,
and use only the top 4 strings)

Chord shapes:

Gb/Db: 0003
Abm/Eb: 2210
Abm7/Eb: 2213
Db7: 0212
Db9sus4: 0213
Db9(no 3rd): 0210
Gb7/Db: 0001
Bbm/Db: 0432

For simplicity, I'll write out most of the chord names without the
altered bass notes (e.g. Gb rather than Gb/Db), except for the Bbm/Db
chord as this alternative bass note has a more important role in the
overall sound of this chord to my ears.

Note that in the main part of the song, the open strings are often
strummed as the chord shape changes, a technique Joni would often
use later on in her career on the guitar, to allow the left hand time
to move between chords.