almost done.

function s3()
turtle.select(3)
if turtle.compare() then
  return true
else
  return false
end
end

function sap()
turtle.select(1)
if turtle.compare() == true then
turtle.select(2)
turtle.place()
elseif
s3() == true then
harvest()
else
turtle.dig()
turtle.select(1)
turtle.place()
sap()
end
end

function logger()
for i=1, 7 do
turtle.up()
end
end

function harvest()
turtle.dig()
turtle.forward()
logger()
end

function cutter()
sap()
down()
turtle.back()
end

cutter()



In my current slots of the turtle I have

S1 Sapling

S2 Bonemeal

S3 Birch Log