Error ModManager.cpp:1560: Error while loading item prototype "tree-wetland-a-sapling" (item): Key "icon" not found in property tree at ROOT.item.tree-wetland-a-sapling
Sounds like you guys are playing with Alien Biomes 0.6.2 or higher, go to 0.6.1 and the mod will load without issue. Reason the mod is having issues with Alien Biomes 0.6.2 and up is because Alien Biomes changed how they display their icons and Arborium has yet to update for the changes that was done. I'm sure an update is in the works, but you need to give the author some time as they can't spend every minute of their time fixing every little thing that happens due to other mods changing something of their own.
Thanks! Cant wait to enable it again!!!
To be honest, a tree wall is much more efficient than a brick wall. Critters won't harm them if avoidable and I can use it to reduce pollution to a tolerable level for free. :D