It is supposed to keep VAPP as a minimum; however I have seen significantly below VAPP below 50 ft RA. There is no alpha floor protection below 100 ft RA, and no windshear warning below 50 ft RA. All this may depend upon Airbus type and modification, of course, so I hesitate to be definite about this for all tails. Nonetheless, below 50 ft RA if my speed decays more than a few knots below VAPP I go-around. I know of no way to simply increase thrust slightly to reduce or ameliorate the speed decay. If you know of a better technique please let us know.