So the scenario is like this:
You begin building you base, before altar is done AOW begins to be builded just near your base outside of first burrow range.
Then you think that instead building the barracs you will build second burrow first to kill the aow, but even then filled with 4 peons damage is not enough to out-dps the eat-tree heal (500 Hp over 30 seconds of a total of 900 hp, i dont even know if it stacks with itself.).
Your hero comes out but still you can out-dps aow heal without losing a big amount of time. If you go harras his base its closed and you cant actually do any damage.
So basic answer should be ignore it, but you cant because it hits like a truck and is constantly forcing repairs or peon burrow, which results in big wood loss, not to mention it can eat trees so fast that you entire forest may get destroyed if you dont attend it.
Honestly, besides my inability to stop that i think that eat tree is a bit over the top, like, come one, more than 50% heal over 30 sec for just one tree? looks a bit too much to me.