Maybe an hunters association jacket.
It is not a uniform. it is a hunting jacket. I can't recall the German name for it.
The cap is a military cap, of course, but the jacket he is wearing bears no insignia that I can see and doesn't look military to me.
"Much that once was, is lost. For none now live who remember it."
It is difficult to see if he is from the German hunting organization or forestry,
but he is anyway wearing a Baschlikmütze, a winter cap, with appropriate
state eagle an cockade
"Wir sollen auch unser Leben für die Brüder lassen" (1.Joh.3.16):
zum Gedächtnis Wilhelm Schenk. Er starb fürs Vaterland am 13. Juni 1916