Resin collection for turpentine in Northern Florida, circa 1936

I found the turpentine industry in Florida to be rather intriguing. They slashed the pine tree’s bark, and installed a metal “trough” that would allow the resin to be collected into buckets. The resin is then processed into turpentine.
In Florida, I assume its the long-leaf pines, that are so prevalent down here, that is their source of turpentine resin.

This brings me to a new question. I’ve seen 40′ trucks loaded with bales of these long-leaf pine needles. What in the world do they use those for? And in such quantity? Mulch? They call it “pine straw”.