is it under any threat or needs to be conserved?
Yes, it is a threat in suburban areas by pollution and by predation by domestic animals.
Australian green tree frog
In suburban areas, this frog is threatened by pollution and by predation by domestic animals. 
where do you find australian green tree frog? Australia and New Guinea does it has any scientific name? Yes, "Ranoidea caerulea".
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Australian green tree frog [SEP] Conservation
Also, some of the frogs have been found to be infected with the chytrid fungus which causes the fatal amphibian disease chytridiomycosis. The frog's status in New Guinea is poorly studied, but in 2002, some 75,000 individuals were exported from Indonesia as part of the pet trade, and this may impact populations in some locations. The frog is present in a number of protected areas in New Guinea, and it has been successfully bred in some Australian zoos. Overall, the main threat to this species is the potential for a widespread disease epidemic.