Tell me why?

Why is there a drain pipe attached to a tree stump?
I am stumped if I know.
Saw this at Morgan McVeigh's cafe and gift shop on the Inverness road, where we stopped for coffee today.
We originally, on this beautiful, sunny day, had ventured up to Huntly, the home of Dean's shortbread, to visit the garden centre there.
Only to discover that it has been superseded into an ASDA.
Oh well, it was a pleasant day for a drive.
Anyway, I have been called up for jury duty tomorrow, so I am not sure if I am looking forward to it or not. I don't do mornings very well.