Greg is a terrestrial plant ecologist at The University of Adelaide specialising in community ecology, macroecology and ecosystem monitoring. He has described 20 new plant species, mapped centres of plant biodiversity, and modelled the impacts of climate change on Australian ecosystems. He has published over 50 peer-reviewed journal papers in these fields.

Greg was the Ecology Lead during the development phase of Wild Orchid Watch, a role which combined input on data collection methods with associated field research dedicated to understanding how whole orchid communities and orchid reproductive success respond to disturbance and other characteristics of habitat patches.