New Zealand has some locally grown eucalypts with sufficient natural durability and these are described in the website under Eucalypts

Of the eucalypts, the bluegum and stringy bark species are durable in ground contact so they will be more than sufficient for decking, therefore suitable varieties include saligna, botryoides, muelleriana, globoidea, eugenoides, microcorys and pilularis.

The eucalypts listed are a slightly higher durability class (Class 2-3) and therefore more reliable as decking.