Good eye, those stacks are almost all pine. A bit of ailanthus mixed in. Most of what I burn is pine and some sweet gum. I'm thinning the forest and trying to release oaks, persimmons, and other mast-bearing trees for the deer and turkey. The previous owner of the land was a plumber so I ended up with a bunch of 2 inch pipe. I put it between concrete blocks then drive T-posts on the ends. Makes a pretty decent stack. I really like keeping the stacks in the barn- keeps the wood dry and clean. Plenty of air flow- no walls, so it dries nicely.
I have a bunch of softer woods also in my stacks, like tulip, aspen and sycamore that I get from thinning them out of my woods. I like having both hard woods and softer woods in the stacks. You will have the perfect mix now with oak with pine... Makes a big difference having that oak for over nighters and those coldest of days. By the way, that barn looks like it's built like a tank. Very cool..... Stacks looks great.
I got a load of 2" black iron sprinkler pipe from my old neighbor that we cut out of a building that he was renovating. Makes for great stacking. Just need to make sure it doesn't roll. I even put it into the Uhaul when we moved. The only reason I don't use it anymore is because I got a pile of 16' pallet rack verticals that had the cross braces cut out. Square stock doesn't roll.
I use the hollow concrete blocks on their side, one pipe in each hollow. It doesn't roll far that way and it is super simple.
