When i did some reading up on beam and pole building for my own
project , some of it was about the japanese methods and timber used ---but way beyond my skill --so i used rough sawn timbers and logs for framework but the tree species for timber is very restricted around my part of the world--and quality stuff is very expensive--so most of what i used was sitka spruce --very coarse and with the odd red pine and larch log---all rough and ready stuff . The japanese sites mentioned working with their
local types of red pine ,black pine ,cedar and cypress ---all fine grained and high quality.