mass data inport for melbourne

IMHO not a good idea (given that I was born there I'm allowed to have an opinion :-)), on the one hand I don't believe we've ever considered keeping tree canopy data in OSM in the first place and 2nd doing so would create a mass of extra polygons that would make editing a real pain. Further there is still lots of useful stuff missing from OSM in Melbourne (buildings, addresses, etc) which would be far higher priority than the proposed import.

Not IMHO: you need to consult the local community and the import mailinglist, read http://wiki.openstreetmap.org/wiki/Import/Guidelines first.