Just forests won't work indeed, there need to be no roads on those tiles.
Otherwise they'd just be moving settlers on tiles north and east of The Nursery, disband The Nursery and creep towards our other towns with combat settler as they did against GONG.
So the only defense against a landed enemy is unroaded forests.
Yep.
Well, if we pillage the roads next to The Nursery, they won't be able to settler there the first turn.
If they get a large stack on land, we may have trouble, cause I assume they will start airlifting units.
I ran some tests and it looks like, if we had good bomber support, a stack of modern armor could take out a stack of modern armor twice it's size. I tried 30 bombers and 30 MA vs. 60 MA, on a clear tile, with a radar tower in support - I ended up with 10 pretty beat up MA on both sides, which, if that was it, would end up with us dying a fast death, as their MA would rip us apart, I think.
So, we need more than 1/2 as many MA as our opponents, or we need some mech infantry. One thing to think about is that a modern armor can attack 2 or 3 times... but an army of modern armors gets only 4 attacks, so if we get an army, we'd be giving up 5 potential attacks from 3 armor, to gain 4 super attacks from the army.
Back to the example: if, however, they opposition lands 30 Mech inf and 30 tanks (which is closer to what FREE might land now - do they have computers and rocketry?), the stack was brought down to 5 mechs and 1 tank, all redlined, while I had 19 MA left over in various stages of pain.