Okay so to cut a long story short, I planted some trees at the optimal range apart (4 cubes between shoots) for lumber and when they shot up I realised that hey, from one shoot comes a raised platform waiting to be built on that will still provide me with heaps of wood while saving me some effort since the floorspace is built out of branches. I haven't played Survival much so I'm still testing out the Treefort. Anyone else used trees as their home? How did that work out for you? Should I make myself an elf skin now?
Secondly. I decided that I quite liked the idea of tree farming up off the ground. Despite creating several dirt patches to grow them on, I haven't had any luck growing them in dirt up on the tops of trees. Is there a certain 'cubic volume' of dirt cubes they need to grow? Is it possible to grow trees on top of trees on top of trees on top- You get the picture.
On a side note: People talking about weapons, tools and fire on other threads. Make a 'fire cube', which you can make somehow (Sacrifice 30 wood or perhaps some iron for a flint which would last longer) which you can then use to burn stuff. For example, make a wall or floor out of wood and have it turn into non-propagating lava for perhaps five minutes when you hit it with the fire cube/flint equipped. Also, while you have one of them equipped, your arrows have flaming tips, which do damage over time to enemies out of water. Good for a hit-and-run attack on a creeper or zombie. Also, flaming arrows could be used to set fire to wood.
An additional weapon would be replacing the bow with a crossbow (Using wood, iron and gold, perhaps?). Bolts have to be made out of iron rather then wood, but the bow fires further and does more damage. Also, bolts could not be lit on fire, so there's a trade-off.
So dirt cubes placed on top of trees won't grow grass, even in sunlight? Is it a contact thing? Do only dirt blocks in contact with grassed dirt blocks grow grass?
I'm off to try this now...
Edit: Okay, I built a solid dirt staircase up to my tree and planted a tree once it finally all grassed over. This takes some time to happen. Then I made a large layer of dirt connected to the grass, waited till that grew grass and planted a sapling. The sapling wouldn't grow until I put a second block of dirt under the first layer.
Lesson learned! It requires dirt 2 cubes high with the top being grassed to grow a tree. It IS possible to grow trees on trees, but it takes quite a while.
I successfully planted a sapling close to bottom level of the map. It took quite some time to provide everything needed for a tree... then I died while repairing the cave after an attack of 5+ creepers. *facepalm*