Are Acacias treated as sub-tropical or deciduous when grown as bonsai?
Some Acacias in the wild adapted well to sub tropical areas. The same specie grows in arid and tropical areas, though their growth rates are influenced. One specie (karroo) grows enormous in the sub tropics but rather stunted in arid areas. Soil composition also has a huge influence.
Most Acacias however are found in arid and semi arid areas. All depends on the species....
All in all I would say an Acacia should be treated as deciduous first and foremost.
Very few Acacias can actually be used for bonsai. Basically only some of the hooked thorned ones. I'm in the process of bullshitting myself by growing on some fever trees (Acacia xanthophloea) that I might be using for bonsai in the future. Will see, but somehow I don't think the long thorns will be aesthetically pleasing. To remove the thorns makes less sense to me.
Question for Dorian....That sweethorn you bent the hell out of.... does the long straight thorns reduce much as the roots are refined?