I ran a 5 minute circuit five times for bark. Here are the results on a x1 harvesting server.
Obsidian Pick w/ Advanced Tool Upgrade = 436 Bark. (Brittle pick will need repairs)
Pickaxe w/ Advanced Tool Upgrade = 348 Bark. (I had to toss over 2,000 branches)
Star Metal Pick w/ Advanced Tool Upgrade = 334 Bark.
Steel Pick w/ Tool Upgrade = 253 Bark.
Iron Pick Without Upgrade = 153 Bark.
I show the location at the start of the video so you don’t have to watch it all.
There are three clusters of dried trees in close proximity in this area. There are a couple more nice spots but this seems to be the best.