This is a creative Spruce Tree Farm with 40 replanting trees and contains a sapling replanter. Only thing you need to do is flick a lever to replant (Could be modified to be completely automatic, I don't know how to make it automatic without conflicting with running drill processes, as tree growing rates are unpredictable

The redstone links uses the first 40 blocks in the creative menu on first input, be aware of any Redstone link conflicts, This could be converted to survival by replacing the creative motors with your own selected power input.