Cork Oak Plantation at the National Arboretum Canberra

The site for the National Arboretum Canberra encompasses Green Hills to the north where historic plantations of Cork Oaks (Quercus suber) and Himalayan Cedars (Cedrus deodara) provided existing forests as a framework to the young arboretum.   The cork oak plantation was listed on the Register of the National Estate in 1981 and on the ACT Sites of Significance Register.

Cork Oak Forest at the National Arboretum CanberraCork oak has a special place in Canberra’s tree history. Commercial cork was formerly an essential component of life jackets, fishing nets and insulation equipment as well as its traditional role as corks in bottles. Cork oaks were planted around early district properties and corks dangling from the brims of the hats of jackaroos and swagmen typify the outback Australian.

Cork oak is essentially fire tolerant. Quercus suber produces little litter in plantations and the bark provides excellent heat protection to the trunk and the foliage is relatively inflammable.

Walter Burley Griffin recognised potential of cork oak for Canberra’s dry climate and, in 1916, sent a supply of acorns to Yarralumla Nursery for trial by Charles Weston. These were sourced from the Royal Botanic Gardens Melbourne and planted in October 1917 at ‘(Green Hills Area) Cork Oak Reserve’. WB Griffin was also the source for acorns collected in 1917 “by Mrs Orme Masson of the University of Melbourne as a contribution to the cork oak plantation” and from trees in the Public Gardens in Kyneton, Victoria.

Disruption of supplies during World War I provided a stimulus for establishment of cork plantations in Canberra. However the project was delayed when, in 1918, the SS Boorara, carrying a shipment of acorns gathered in Spain for planting in Canberra was torpedoed. Records at Yarralumla Nursery also show “four cases of 30,000 acorns shipped per SS Ismailia – consignment lost at sea.” Replacement supplies were obtained and, by 1920, 9600 cork oaks had been planted at Green Hills on an area covering eight hectares.

Yarralumla Nursery’s records also list cork oaks planted in 1921 at the Brickworks Yarralumla, 1922 for W Hughes PM and 1926 in Presentation Avenue. In the 1940s, seed was sourced from Portugal, Morocco and Madrid.

Cork Oaks in Australia

In 2003, correspondence between tree experts John Hawker and Dr Robert Boden, led to an article in ‘The Botanic Gardens’ newsletter in which they said that the earliest known record of Quercus suber in Australia is in a NSW Botanic Gardens report of 1853-4 which records cork oak received from Acton Sillitoe Esq.

The oldest cork oak in Australia was planted c 1857 below the Gatehouse in the Royal Tasmanian Botanic Gardens and the largest cork oak in Australia was a tree at Tenterfield NSW planted in 1861, which stood at 25 metres in 2003.

In 1996, a report on the magnificent cork oak growing in the grounds of the police residence in Wallace Street, Braidwood said it was planted c. 1800.

Cork Stripping in Canberra

The bark of a Cork Oak tree.Professor Lindsay Pryor, in his oral history recorded for the National Trust of Australia (ACT) by Matthew Higgins in 1992, recalls first seeing Canberra’s cork oak plantation in 1934 and the trees had grown well. In 1947 Pryor visited Morocco where he saw how cork was harvested from the bark of the trees. By coincidence, a firm in Melbourne was importing cork and pressing it to make blocks to put into refrigerators as door insulation. The firm, GP Embleton & Son, knew of the Canberra plantation and wanted to try cork grown locally to see if it matched the imported material.

Pryor had two people who were good at timber working and axe work, tree surgeon Jack Newlyn and Tom Rawlings, who did some preliminary cork stripping with Pryor and the harvest of 19cwt was sent to Melbourne. A second quantity was sold to Embleton’s in May 1951 (‘A Pryor commitment’, thesis of Bernadette Hince, 1992). John Diehm, who worked in tree management for 47 years, knew Jack Newlyn well and said Jack was in charge of the only tree surgery team in Canberra and Tom Rawlings was in charge of the maintenance section of the department.

In the ‘Glenloch Cork Oak Plantation draft conservation plan’ (1989) by Dr John Banks, Florence, Taylor and Egloff, is a photo taken by Pryor of Rawlings doing the first cork harvesting in 1948. Pryor recalled that in the 1940s Yarralumla nursery foreman Tom Sharp and chief nurseryman John Hobday said the 1920 cork oak seedlings for Glenloch were raised using acorns from local cork oaks on Campbell’s property, Duntroon.

This report also states that Griffin’s continental arboretum did not include the Glenloch Plantation site (which was in the Agricultural Reserve, west of the European sector) and that it was a small experimental production plantation, the trees closely spaced to produce long straight boles.

The first stripping from a tree, when the trees are more than twenty years old, produces what is called ‘virgin cork’. It is then not sufficiently watertight to make stoppers for bottles. These require cork from the second or later strippings which are done every ten years.

Dr. Geoff Wood was one of 14 students in the 1953 class at the Australian Forestry School, Yarralumla. He recalls the Principal, Dr Max Jacobs, telling students that, at the request of the Director General of the Commonwealth Forestry and Timber Bureau, GJ Rodger, they were to do “the first test debarking of trees” in the cork oak plantation. Dr Jacobs demonstrated the procedure on site using a sharp half-axe (half the weight of a standard axe) and two jemmy bars, then each student debarked a tree. Geoff Wood took a photo at that time of defects at the breach of the double-leader tree he debarked.  On 11 April 2011, 58 years later, he was able to locate and identify conclusively the same tree.

Pryor says in Canberra cork from a second stripping in the 1970s was sent to Comcork in Melbourne which used cork for stage gaskets for internal combustion engines, cork tiles and heels for shoes. This trial produced bottle stoppers of quite good quality. In 1979 ACT Forests branch did a stripping which generated ten tonnes of cork which was used for potters and model railway enthusiasts.

During the 1980s special heritage week visits and ranger talks were held in the cork oak plantation. Neil Cooper, now Manager of Fire, Forests & Roads with ACT Parks & Conservation Service, recalls that in 1988 he and Wayne Lemke of the inventory and tree measuring crew did the cork harvesting. Cooper was photographed showing cork removed from a section of one tree using a special axe that had been imported from Portugal.

In April 1993, for an ACT Forests Heritage, cork stripping was demonstrated at Green Hills by Bob Burdick, and those of us who attended were given cork oak mats to use as coasters.

In 2001 two cork strippers, cousins Manuel Silva and Manuel Graca, came to Canberra from Ponte De Sor in the heart of Portugal’s cork growing region. The men were brought to Australia by the Portuguese company Amorim, the world’s largest cork producer. An interpreter said that the oldest cork oak tree still in production in Portugal was 218 years old and, in the year 2000, it produced enough material for 60,000 wine corks.

A local initiative, led by the Chief Minister’s Department and the Canberra District Wine Industry, considered a ‘local corks for local wines’ promotion. In 2003 a group from ACT Forests including Tony Bartlett and Neil Cooper, were given bottles of wine to thank them for saving the cork oak plantation in Canberra’s devastating fires. Cooper still has his bottle and oak coasters made from a plantation harvest.

In November 2005, for the first memorable open day of the Arboretum, an associated event was held in the cork oak plantation.  There was dancing in a paddock by a Portuguese group from the South Coast, wine stalls, sausage sandwiches cooked by the SES, and three Portuguese men harvesting cork from the trees. The men had been commissioned by ACT Forests to harvest the bark over a two-week period and the bark was to be sold to plant nurseries to grow orchids. Executive assistant at Portuguese cork trader Vinocor, Henrique Silva, said knowledge of the harvesting practice was passed from generation to generation.

Visitors to the public demonstration were told that the bark of cork oaks is fire-retardant and that this property would have saved the plantation in the 2001 and 2003 bushfires that threatened the Green Hills area. A large piece of cork bark removed on this occasion is being held for display to future visitors at the National Arboretum Canberra.

A walk among the Cork Oaks of Canberra

At the Lindsay Pryor National Arboretum, on the shores of Lake Burley Griffin just to the east of the National Arboretum Canberra, are two substantial plantations of cork oak. No records have been found which give the planting date for these evergreen trees but it is likely they were planted after winter and therefore not included in the July 1955 distribution planting keys.

Professor Lindsay Pryor was then Director of Parks and Gardens and the tree plantings were done at the request of the Governor General, Sir William Slim, who wanted the view from Government House across the future lake to be more sympathetic. The site, at present, is fairly untamed but provides a wonderful resource for dog walking and appreciating silviculture.

In “Trees and Shrubs in Canberra” (1991, 2001) Pryor and Banks list among notable trees of Canberra the cork oak (Quercus suber) at the corner of Robert Campbell and Parnell Roads, Duntroon. This tree overhangs a white picket fence outside the house of the Director of Military Art. It was planted in 1861 and was the source of acorns for local plantings including part of the cork oak plantation at Green Hills. Rather felicitously, an old label attached to the trunk is inscribed with the botanical name “Quercus super”.

At Westbourne Woods, now within the Royal Canberra Golf Club’s lease, there are three plots of cork oaks. The four trees between fairways 18 and 27 were planted between 1914-18 and they are 19 metres in height. Six cork oaks near the tee on the 16th hole are of similar dimensions while six trees between fairways 15 and 16 are around 21 metres. Visitors are able to see these cork oaks on walks arranged by Friends of ACT Arboreta held on one Sunday morning each month.

In Young Street, Barton, outside the Australian Federal Police College, is a pair of cork oaks. One was measured at 16.5 metres high in 1991 with a girth at breast height of 2.3 metres. These trees were part of the 1946 plantings in Canberra. Three old cork oaks in the car park next to Lake boat hire at Acton have gnarled trunks and some die back. There are three old cork oaks in Telopea Park opposite Manuka Swimming Pool.

Just off Bowen Drive in Barton, in front of the 2004 Landmark apartment buildings, are seven cork oaks which were part of the original Riverside plantings. These trees have been given wide ‘saucers’ for watering and are well mulched and, in 2011, most are bearing a heavy crop of acorns.

Canberra Frank Grossbechler, who collects seed for the Government’s Yarralumla Nursery, said he collects acorns from a cork oak in Bonney Street, Ainslie and from three cork oaks at Havelock House on Northbourne Avenue which were planted in the early 1950s. Grossbechler was one of a gang with Parks & Gardens who planted cork oaks in 1956 near the Air Disaster Memorial near Fairbairn, under the direction of Pryor, who also arranged plantings at the Cotter Road plots at Curtin, using seed from the Green Hills cork oaks (Hince’s thesis, Pryor pers. comm. 1989).

Behind Dunstan Street in Curtin is a wonderful stand of cork oaks which Curtin resident and tree expert, Sue Johnston, says was part of experimental plantings undertaken by Pryor in that suburb around 1948. There are hundreds of Quercus suber in the plantation and these were burnt in the 2003 bush fires but saved by helicopters flying over from Curtin Oval to dump water on the trees. Many of the trunks are still blackened but the trees started to recover three years after the fire and now have a splendid green canopy.

There are three sturdy cork oaks on open land at the corner of Wisdom and Groom Streets in Hughes and in late autumn, white cockatoos can often be seen feasting on the acorns.

In the suburb of Red Hill, Torres and Vancouver Streets are interplanted with cork oaks (Quercus suber) and holm or holly oak (Quercus ilex).  The cork oaks are distinguished by their thick, corky, deeply furrowed bark that is warm to the touch and makes a hollow sound when thumped with the palm of the hand. In Bonney Street, Ainslie, there are three cork oaks among the holm oaks.

The gnarled Red Hill cork oaks are bear a fine crop of rich chocolate brown acorns set in handsome beige cups with scales that are fringed at the rim. The leaves are glossy, dark green above and paler, grey-green and hairy below and bear five small teeth on each side.

As you walk through the National Arboretum’s cork oak plantation, reflect on Dr John Banks’ description of Weston’s planting pattern as a quincunx, an arrangement of five trees in a square or rectangle, one at each corner and one in the middle. It is the radiating cathedral-like avenues which lend character to the planting today.