Apart from a general interest in horticultural plant science, revegetation and ecology, Greg has a specific interest in all aspects of arboriculture, which is the scientific study of the cultivation and management of trees. He has contributed to the development of Australian Standards in pruning, protection of trees on development sites and amenity tree evaluation and has been a major speaker at conferences in Australia, China, Israel, Hong Kong, USA, France and New Zealand. He was the inaugural president of the International Society of Arboriculture, Australian Chapter. He has been a regular on Melbourne radio, particularly with ABC 774 and 3AW.
He has been a member of the National Trust of Victoria’s Register of Significant Trees since 1988 and has chaired the committee since 1996. Greg was on the Board of Greening Australia (Victoria) 1988 – 2012. He has been on the board of TREENET (chair 2005-2019) since 1999 and has been on the Board of Sustainable Gardening Australia since 2002. He was a ministerial nomination for the Trust for Nature from 2009 to 2017 and for Yarra Park from 2010 – 2020. He has also served on a number of industry and TAFE sector committees, especially those that deal with curriculum and accreditation matters.
He continues to pursue an active research profile in any matters that relate to trees in the urban environment and revegetation. He has written three books, seven book chapters and has had some 180 papers and articles relating to tree biology and management published. He was awarded an OAM in 2017 for services to the environment, particularly arboriculture.