Seriously though, one option (if you use Biomes O Plenty or similar) would be to disable biomes that generate trees. That'll leave you with wastelands, deserts, marshes and other lovely holiday locations. Trees can still generate rarely along rivers. If you also add in Natura, that uses it's own rules for generating trees, some depend on biomes, some depend on other rules for spawning.
Finding your first tree will be a challenge, you'll be wanting to guard your first sapling.
Did a similar thing in a 1.5.2 pack with a wasteland theme with old ruins across the landscape. Us server players were salvaging what wood we could get from the ruins, discussing what that wood should be used for, until we managed to find a MFR rubber tree in a swamp (hundreds of chunks from spawn), and shortly after that some natura trees on a river and a greatwood tree from Thaumcraft.