In all of the alpha versions with the new large tree trunks, all trees make stone sounds instead of log/wood when being chopped. Also, all roots on big trees instantly break when clicked.

I am currently running the alpha 0.9.1d.

Forge version: 14.23.5.2772

It appears that after further testing, some smaller tree trunks do make the proper sound when harvested. Any that are fully grown or are larger than 1 block thick do not though.