Feller 2

function forward(aantal)
  for i = 1, aantal do
    turtle.dig()
    turtle.forward()
  end
end

function tree()
  if turtle.detect() then
    turtle.dig()
    turtle.forward()
    i = 0
    while (i < 7) and turtle.detectUp() do
      turtle.digUp()
      turtle.up()
      i = i + 1
    end
    while turtle.down() do
    end
    turtle.digDown()
    turtle.select(1)
    turtle.placeDown()
  else
    forward(1)
  end
end

while turtle.getFuelLevel() < 500 do
  term.clear()
  term.setCursorPos(1,1)
  print("You need to refuel, put coal in slot 2")
  io.read()
  turtle.select(2)
  turtle.refuel()
end
while turtle.getItemCount(1) < 6 do
  term.clear()
  term.setCursorPos(1,1)
  print("There need to be at least 6 saplings in slot 1")
  io.read()
end

turtle.turnRight()
turtle.turnRight()
turtle.down()
forward(4)
turtle.turnLeft()
forward(3)
tree()
for i = 1, 2 do
  forward(2)
  tree()
end
turtle.turnRight()
forward(2)
tree()
turtle.turnRight()
for i = 1, 2 do
  forward(2)
  tree()
end
forward(4)
turtle.turnRight()
forward(7)
turtle.up()