ToLazyToThink's tree turtle

 -- This is meant for a 1x1 tree, with transposers or equivelent to pick up drops/sapplings,
 --   a fuel chest on the right, a sappling chest underneath, an optional bone meal
 --   chest behind and an optional "watcher" connected via rednet to pause logging
 --
 -- If not using bonemeal, set boneChestSlot to -1
 -- If not using a watcher, set watcherID to -1
 -- Chest can share the same slot as long as they are the same type to turtle.compare(),
 --   enderchest compare() equal even if they have different colors

woodSlot = 1
sapplingSlot = 2
chestSlot = 3
fuelChestSlot = 3
boneChestSlot = 3
startSlot = 4
endSlot = 16

watcherID = 30

minFuel = 200

function plant()
  if turtle.getItemCount(sapplingSlot) < 2 then
    turtle.select(sapplingSlot)
    turtle.suckDown()
    if turtle.getItemCount(sapplingSlot) < 2 then
      print("Out of Sapplings")
      sleep(30)
      return plant
    end
  end

  dropExtras()
  turtle.select(sapplingSlot)
  turtle.place()
  print("waitForGrowth")
  return waitForGrowth
end

function waitForGrowth()
  if not keepLogging() then
    sleep(5)
    return waitForGrowth
  end

  if compare(woodSlot) then
    checkFuel()
    print("cutUp")
    return cutUp
  else
    if boneIt() then
      -- we'll get it next time
      return waitForGrowth
    end
    sleep(15)
    return waitForGrowth
  end
end

function cutUp()
  turtle.select(sapplingSlot)
  turtle.digUp()

  if turtle.detect() then
    turtle.dig()
  else
    print("returnHome")
    return returnHome
  end

  moveUp()

  return cutUp
end

function returnHome()
  turtle.dig() -- in case of side growth

  if compareDown(chestSlot) then
    dropExtras()
    checkFuel()
    print("plant")
    return plant
  end

  turtle.dig() -- in case of side growth
  moveDown()

  return returnHome
end

function watchWood()
  print("watching")
  rednet.open("right")
  while true do
    local id, msg, dist = rednet.receive()
    if msg == "wood-status" then
      if redstone.getInput("back") then
        rednet.send(id, "wood-stop", false)
      else
        rednet.send(id, "wood-go", false)
      end
    end
  end

  return nill
end

function boneIt()
  if boneChestSlot > 0 and not compare(woodSlot) then
    dropExtras()

    turtle.turnRight()
    turtle.turnRight()

    turtle.select(endSlot)
    turtle.suck()

    turtle.turnLeft()
    turtle.turnLeft()

    for i = 1, 10, 1 do
      if not compare(woodSlot) then
        turtle.select(endSlot)
        turtle.place()
      end
    end

    dropExtras()

    if not compare(woodSlot) then
      print("Boneing failed")
      return false
    end
    return true
  end

  return false
end

function resetHomeDir()
  while compare(fuelChestSlot) or (boneChestSlot > 0 and compare(boneChestSlot)) do
    turtle.turnLeft()
  end
end

function dropExtras()
  for i = startSlot, endSlot, 1 do
    turtle.select(i)
    turtle.drop()
  end
end

function compare(slot)
  turtle.select(slot)
  return turtle.compare()
end

function compareDown(slot)
  turtle.select(slot)
  return turtle.compareDown()
end

function checkFuel()
  if turtle.getFuelLevel() < minFuel then
    resetHomeDir()
    turtle.turnRight()

    while turtle.getFuelLevel() < minFuel do
      dropExtras()
      turtle.select(16)
      turtle.suck()
      turtle.refuel()
      if turtle.getFuelLevel() < minFuel then
        print("Not enough Fuel")
        sleep(30)
      end
    end

    print("refueled")
  end

  resetHomeDir()

end

function moveUp()
  while not turtle.up() do
    print("can't move up")
    turtle.attackUp()
    turtle.digUp()
    sleep(5)
  end
end

function moveDown()
  while not turtle.down() do
    print("can't move down")
    turtle.digDown()
    turtle.attackDown()
    sleep(5)
  end
end

function keepLogging()
  if watcherID < 0 then
    return true
  end

  rednet.open("right")
  rednet.send(watcherID, "wood-status", true)
  local id, msg, dist = rednet.receive(30)
  if id == nill then
    print("couldn't reach watcher")
    return false
  end

  return msg == "wood-go"
end


function determineState()
  -- is this the watcher?
  if watcherID == os.getComputerID() then
    print("Determined state = watchWood")
    return watchWood
  end

  -- nope, we're a logger

  if compareDown(chestSlot) then
    resetHomeDir()
    dropExtras()
    checkFuel()

    if turtle.detect() then
      print("Determined state = waitForGrowth")
      return waitForGrowth
    end
  elseif turtle.detect() then
    print("Determined state = cutUp")
    return cutUp
  end

  -- it's possible we removed the log in front of us
  --  before the reset, it's also possible we were
  --  returning home

  turtle.digUp()
  moveUp()
  if turtle.detect() then
    print("Determined state = cutUp")
    return cutUp
  else
    print("Determined state = returnHome")
    return returnHome
  end
end

state = determineState()
while true do
  state = state()
end