It’s time to plant for our future
The Australian Garden History Society (AGHS) has held its annual conference in Hobart. Some 250 delegates, mainly from mainland states, descended on Hobart and its gardens to soak up four days of lectures and tours. Soak up it was as, in true Tassie style, there was rain. Gardeners, however, are tough customers so came well prepared.
The weather, or more importantly climate and its future, was one of the items up for discussion in a conference titled “Landscape on the Edge”. The “edge” in this case being not just Tasmania’s location on the edge of Australia, but how our landscapes are poised on the edge of change.
Rather than only looking back, the AGHS is keen to look forward to help protect gardens and landscapes in the future. The AGHS launched its position statement on climate change at the conference. This document urges all gardeners and those in charge of major public gardens and built landscapes to plant with an eye to the future and what the climate may be.
The position statement, titled “Time to adapt to climate change”, outlines the key actions that need to be taken to protect landscapes and plant species from climate change impacts. The document, described as a “living document” will be developed over time and is available on the AGHS website (gardenhistorysociety.org.au).
The document was launched by the AGHS’s patron, Professor Tim Entwisle, who is also head of the Royal Botanic Gardens Victoria.
HEADING NORTH
Professor Entwisle is already gearing up two of Victoria’s botanic gardens – the Royal Botanic Gardens Melbourne and Cranbourne – for a hotter, drier future. He says climate modelling shows Melbourne’s climate gradually changing to be by 2090 more like the current climate in Dubbo in the central west of NSW. That’s a city around 900km and more than an eighthour drive north of Melbourne. He is looking north in Australia and to warmer zones in Europe and Asia for species that do well when long-term plant selections are made. He is particularly interested in trees as these plants, if correctly chosen, will be our legacy for this potentially hotter drier world. While Dubbo isn’t arid (it has a fine Japanese garden with healthy stands of flowering cherries and other plants familiar to Tasmanian gardeners), it is quite a different growing environment from southern Australia.
WHITE OAK REPLACEMENT
The Royal Botanic Garden in Melbourne had to put this new, climateinformed planting plan into practice. The garden is well known for its collection of mature oak trees on the Oak Lawn, a popular area for visitors. Recently a mature white oak (quercus alba) collapsed. No one was injured as the first limbs fell in the early hours of the morning. When the remaining tree also collapsed later in the day, the area was safely fenced.
A sculpture using the fallen timber has been created to commemorate the venerable tree while Professor Entwisle and his horticultural team look at planting options among oak species that will grow in a warming climate rather than replace it with the unhappy white oak, a long-lived species in its native habitat of eastern and central North Amercia.
Some of the options are the holm oak (Q. ilex) and Algerian oak (Q. canariensis), evergreen oaks from warm parts of the Mediterranean.
To help find trees and other plants of the future, Macquarie University in Sydney, has developed a plant list that feeds into climate models. “Which Plant Where” is an app designed to be used by landscape designers, landscape architects and horticulturists to future-proof planting choices. It alerts planners to species that may no longer be suitable, as well as highlighting species that are safer options (see whichplantwhere.com.au).