Dr Jennifer Gardner
In this presentation, I will give a brief background of TREENET and its mission and introduce the Advisory Board. I will explain the role of Waite Arboretum in TREENET and conclude by indicating some of the attractive species in the Arboretum which I think merit consideration for street trees.
Background of TREENET
The need for a collaborative approach to urban street trees is clear. When David Lawry approached me with the idea of forming TREENET, I responded enthusiastically. The inspiration for TREENET followed a seminar, hosted by the Royal Australian Institute of Parks and Recreation on ‘Trees in the Urban Environment’ held at the Waite Institute in 1995 and a ‘Visions of the Future’ workshop held in 1996 which brought together a cross section of people who use the Waite Arboretum as a resource for research, teaching, training or as a reference collection for tree selection. At the same time the notion of forming cluster groups and partnerships with industry and government authorities was really taking hold in South Australia, supported by the SA Chamber of Commerce. In the earliest stages TREENET received strong support from Henry Polec at Transport SA and that Department provided start up funding.
Establishment of TREENET
The inaugural meeting of the TREENET collaborative partners was held in February 1997 and brought together representatives of Local and State Government as well as the nursery industry, design professionals and the education sectors.
This year, with grants from Transport SA, Local Government and the Nursery Industry, TREENET has been able to employ a postgraduate student, Gareth Hodges, to develop a business plan, staff the office, and conduct a street tree survey.
The Director of the Waite Institute Prof. Malcolm Oades has generously allowed TREENET to have office space in historic Urrbrae House where the Arboretum office is also located, and we are very appreciative of this.
Mission of TREENET
The mission of TREENET (Tree and Roadway Experimental and Educational Network) is to improve our streetscapes through better production, selection, establishment and maintenance of street trees and to broaden the palette of suitable species available which have the best qualities without attendant problems.
TREENET aims to provide a focal point for the exchange of information about street trees and to facilitate the gathering and dissemination of useful data by encouraging the establishment and monitoring of trial sites.
TREENET Advisory Board
The 14 members of the TREENET Advisory Board have between them a wide range of expertise and interests relating to street trees. In addition to myself the members of the Board are as follows:
David Lawry (Chair) is the Director of Lawrys Landscapes and Nurseries specialising in growing advanced trees for streets and parks in an urban situation.
Mark Adams is presently Landscape Design Officer with the City of Salisbury. He brings to the Board knowledge of local government practices and experience in urban streetscape development.
Malcolm Campbell is a professional horticulturalist with 25 years experience. He is a radio and television presenter and a national gardening writer.
Andrew Ciric is the Senior Project Engineer – Strategic Services, City of Mitcham and brings to the Board both Local Government and engineering perspectives.
Dean Cresswell is Assistant Principal School Focus at Urrbrae Agricultural High School and is responsible for overseeing the school’s specialist programs in horticulture and related studies. He also liaising with research organisations, post secondary education and industry groups on behalf of the school.
Judy Fakes has lectured at the Ryde College of TAFE since 1979 specialising in soils and arboriculture. She has developed specialist course in Tree Surgery and Tree Care for Electricity Workers and is a consultant to local councils and electricity supply authorities.
Anne Frodsham is the Nursery Industry Development Officer for South Australia. She oversees the implementation of the national nursery industry Best Practice scheme in South Australia and works to keep nurseries abreast of new developments and moving towards Best Practice.
Kevin Handreck is Managing Director of Netherwood Horticultural Consultant which provides information on potting media, soils, fertilisers and related matters to all horticultural industries.
Dr David Jones is Senior Lecturer in Landscape Architecture at Adelaide University and a prominent heritage landscapes and gardens consultant.
Kym Knight is an arboricultural consultant and runs a tree contracting business focussed on quality tree care. He sees his role on the Board as contributing arboricultural expertise in a broad context to the activities of TREENET.
Dr Greg Moore is Principal and Head of Burnley College of the Institute of Land Food Resources at Melbourne University. He has contributed to the development of Australian Standards in pruning and amenity tree evaluation, written a book and over 50 research papers relating to tree biology and management.
Trevor Nottle has come from a 30 year career in education in the schools sector of DETE. He is currently Manager – Education at the TAFE Horticulture Centre.
Henry Polec is the Senior Landscape Architect in Transport SA where his main activities include Project Coordination, Landscape and Irrigation Design, and Contract and Consultant Management.
The Waite Arboretum provides an ideal home for TREENET. The Arboretum, which was established in 1928, contains over 2,200 trees and shrubs from all over the world, grown under natural rainfall (an average of 625 mm a year). Assessing the suitability of trees for particular conditions of soil and climate takes many years. The long term security of the Arboretum is guaranteed by the terms of Peter Waite’s gift of land to the University, and by the Arboretum’s listing in the National Estate, State Heritage Register and The National Trust Register of Significant Trees. This ensures that the Arboretum will continue to be a good testing ground for years to come.
Not only is Waite Arboretum internationally recognised, but it also is part of a wider horticultural facility which includes the University’s Department of Horticulture, SARDI (South Australia Research and Development Institute), PIRSA (Primary Industries Research SA) and CSIRO Division of Horticulture all located on the Waite Campus and the TAFE Horticulture Centre and Urrbrae Agricultural High School on the adjacent Urrbrae Campus. All these collocated institutions have the potential to make a significant contribution to arboriculture through research and training.
Street tree suggestions from Waite Arboretum
I will conclude by presenting a selection of trees in the Waite Arboretum which have not been used or are uncommon in South Australia as street trees but which I think merit consideration. Some previous recommendations from the Arboretum are currently being trialed eg:
Corymbia eximia, yellow bloodwood (being trialed by the City of Onkaparinga);
These are some of the many species being trialed in the City of West Torrens; as well as:
Zelkova serrata Japanese zelkova (City of Burnside).
Where TREENET trials involve species not already in the Waite Arboretum, reference specimens are planted there eg: Cupaniopsis anacardioides tuckeroo and Elaeocarpus reticulata blueberry ash which are being trialed in City of Port Lincoln.
The first group of suggestions are deciduous exotic species.
Aesculus hippocastaneum horse chestnut [#861 (B9)] from Greece and Albania is well adapted to our climate and has a show of pinkish white flowers in spring.
The smaller, more compact A. x carnea (A. hippocastaneum x A. pavia) red buckeye from SE U. S. A. [#261 (H9)] has spectacular sprays of deep pink flowers. Having large fruits these species may be more suitable for grassy verges.
Pistacia chinensis Chinese pistachio [#346 (F8), # 862 (B8)] from China and Japan is a very attractive shade tree and consistently produces a spectacular display of crimson foliage in autumn. The smaller P. atlantica the Mt Atlas mastic tree from Mediterranean also does well here.
There are now many commercially available selections of Pyrus calleryana callery pear some of which are represented in the Arboretum. But one selection which was made by Dr David Symon we are calling ‘Lynington’. The original Arboretum specimen is no longer there, but the four trees in the garden of Urrbrae House were budded from that tree. Each year the spring blossoms are breathtaking and in some years the autumn colour is a rich golden flame. Being one of the Asian pea pears, the fruits are small (about 15 mm across) and hard. They remain on the tree for a long time and are generally eaten by birds before they fall. This cultivar is now being produced by several South Australian nurseries and Flemings in Victoria from budwood from these four trees.
Solar access in winter is often an important issue in the selection trees in close proximity to houses. However, if an evergreen tree is sought, there are a several attractive species in the Arboretum which do well in our climate.
Vepris lanceolata white ironwood [#372 (F9)] in the citrus family has attractive glossy green leaves with undulating margins. The fruits are very small and would not be a nuisance.
Nuxia floribunda vlier [#369, #381 (F9)] is striking in flower and of good form, although the dead flowers tend to remain for some time, detracting somewhat from the appearance. Both species are from South Africa. I know of no commercial source of these species, and our Nuxia has never set seed.
Vitex lucens puriri [#334 (G8), #374 (E9)], a native of New Zealand has dense glossy green leaves and spreading branches making it a good shade tree. Distinctive clusters of rich red flowers are produced throughout the year, but are most abundant in spring. Formative pruning would be needed to lift the canopy.
The Waite Arboretum has a fine collection of oaks, and many of these I think have potential as street trees, especially those from homoclimes such as California and the Mediterranean. The disadvantages of oaks are that some species are slow growing or do not respond well to transplanting, although some are obtainable as containerised specimens to 1.8 m. Once established, however, oaks are long-lived and very attractive. Acorns can be a problem unless the trees are planted in a wide verge.
Evergreen oaks which I think merit consideration are: