But it's also not vineyard prunings.
This is a burn pile, the result of ripping out an old vineyard (goodbye, Pinot Grigio) in preparation for planting new vines.
As you can see, 5 acres yielded three massive piles of defunct vines awaiting immolation. John Rodeno at 6'2" shows just how big those piles are. Bring your own marshmallows for the next burn day.