Blue gum: a walk in the light green of Dalrymple-Hay
By ALEC SMART
Dalrymple-Hay Nature Reserve is featured as one of Ku-ring-gai Council’s prime nature walks, and on National Parks and Wildlife’s (NPWS) discovery program.
The towering arboreal canopy of blue gum high forest, dominated by blackbutt (Eucalyptus pilularis) and turpentine, with its dense mid-storey of shrubbery and understorey of native ferns, provides a safe habitat for a diverse range of flora and fauna - popular with bushwalkers and wildlife watchers.
Blue gum high forest is a distinct community of trees, orchids, grasses, shrubs and assorted ground-covering flora that is unique to the Sydney region and not found elsewhere in Australia. So-called ‘high’ because of the sky-conquering canopy its tall trees create, providing food and shelter for a diverse range of airborne and ground-dwelling native animals and insects.
Several species of eucalyptus trees are known as ‘blue’ gums, one of which, Eucalyptus saligna, the Sydney blue gum, is typically the main component of blue gum high forests, and they live for over 200 years.
Blue gum high forest is endangered and found in limited pockets across the northern suburbs of Sydney, including Ku-ring-gai, Hornsby, Lane Cove, Willoughby, Baulkham Hills, Ryde and Parramatta, the largest of which is less than 20 hectares and all surrounded by urban development.
Historically covering large areas of the shale-capped ridge-tops of Sydney’s northern districts, less than 5 per cent of the estimated 3700 hectares of blue gum high forest that was prevalent throughout the Sydney basin, prior to Europeans’ arrival in 1788, is still standing.
Of this, less than 1 per cent of the total area of blue gum forest is protected inside national parks.
This reduction is because of the historic popularity of the tall, straight Sydney blue gum for timber production. Throughout the 1790s and well into the 1800s, the tallest trees, which can reach over 30 metres in height and 8 metres across their base, were felled for houses, wharves, bridges, fence posts and rail and tram sleepers.
The wood, which is hard, even-textured and easy to shape, was also highly prized for boatbuilding, wall panelling, flooring and furniture production because of its rich dark honey colouring.
In St Ives, the 10.768-hectare Dalrymple-Hay Nature Reserve, incorporating neighbouring Browns Forest and bounded by Mona Vale and Rosedale roads, was declared a protected forest in Jan 1972.
It was named after government surveyor Richard Dalrymple-Hay, first Chief Forestry Commissioner for NSW. Dalrymple-Hay acquired the tract of land in the 1920s as a ‘demonstration forest’ after it was ignored by timber merchants.
However, it wasn’t until the mid 1990s that Dalrymple-Hay and blue gum high forest in general was formally recognised as environmentally-threatened, thanks to intense lobbying by groups such as STEP (South Turramurra Environmental Protection).
It was another decade, in 2005, before the Commonwealth Minister for Environment and Heritage listed blue gum high forest in the Sydney Basin as ‘Critically Endangered’ under the NSW Threatened Species Conservation Act 1995.
Around 180 native plants have been identified in Dalrymple-Hay reserve, including shrubs like maytenus and hairy lolly bushes (aka downy chance); small trees like muttonwood and the parasitic native cherry tree; ferns like false bracken (aka rainbow fern); and large trees such as turpentine and several species of Eucalyptus ranging from the dominant blackbutt and Sydney blue gum to grey ironbarks and angophora (aka Sydney red gum), many of which are over 40 metres in height.
Dalrymple-Hay sustains a fascinating array of native wildlife.
Among the high flyers are: bats, including the grey-headed flying-fox (Australia’s largest bat, which eats the flowers of the blue gum and is an essential pollinator and seed disperser), and several insectivorous microbats from Sydney’s 19 recorded species; parrots, including rainbow lorikeets, king parrots, crimson rosellas, sulphur-crested and the critically-endangered glossy black cockatoos; and other birds ranging from pardalotes, white-eyes, currawongs, wrens, black-faced cuckooshrikes and powerful owls (that prey on ringtail possums).
Other tree dwellers include the possums: ringtails, brushtails and sugar gliders.
Further down on the forest floor, elusive swamp wallabies have been spotted as well as the ubiquitous brush turkeys, which provide an essential service for blackbutt and blue gum seeds that need bare sunlit soil to germinate, by raking up leaf litter and exposing the earth.
Dalrymple-Hay Nature Reserve and Browns Forest
Where: St Ives, on Sydney’s North Shore, approx. 20km from the CBD via Pacific Hwy then Mona Vale Rd
Open: sunrise to sunset
Best time to visit: early morning when the birds are singing
Entry: via Mona Vale Road (to the west) or via the corner of Vista Street and Rosedale Road (on the eastern side).
There is no public transport to the reserve nor public car parks in the vicinity.
Photos: Alec Smart