A contest for the title of the tallest has taken place
at the Orokonui Ecosanctuary, writes general manager Chris
New Zealand's tallest tree, a mountain ash, has reached a
height of 80.5m in the Orokonui Ecosanctuary. Photo by R.
Dunedin has New Zealand's tallest tree. Is it a kauri?
Kahikatea? Rimu, even?
No, it is an 80.5m Australian gum, a mountain ash,
Eucalyptus regnans, and it is growing in the Orokonui
Ecosanctuary. It is the only tree in New Zealand above 80m.
It has long been known that New Zealand's tallest tree was at
Orokonui in the plantation of gums near the bottom of the
valley. A recent measurement exercise shows that another gum
tree in the stand has surpassed the previous record-holder,
also a mountain ash.
Two surveyors from Washington State in the United States
recently spent time in New Zealand measuring all the tall
trees using survey lasers and the sine method.
This species of gum is the second-tallest species in the
world behind the coast redwood, Sequoia sempervirens, of
California. In its Australian home, in Tasmania and Victoria,
the mountain ash has been recorded at heights of around 120m.
New Zealand trees tend to be impressive in girth, rather than
New Zealand's largest indigenous tree, the kauri Tane Mahuta,
is only 51.2m in height but 13.77m in diameter. The tallest
New Zealand tree species is the kahikatea, which reaches 60m.
However, before the last ice age, eucalypts did grow in New
Zealand. Fossil eucalypt leaves have turned up in sediments
more than 20 million years old in Central Otago.
The original planting of gums in Orokonui Valley was made
about 1870, probably as a boundary line. A fire swept through
the lower valley in 1907 and the trees seeded prolifically on
the cleared and burnt land, covering about 2.4ha. Now this
area is a grove of eucalypts in close formation within the
lower (north) end of the ecosanctuary.
Ecosanctuary staff and volunteers control their spread.
In 1982, Frank Pepers, then a research technician for the New
Zealand Forest Service, was employed by the authors of the
book, Great Trees of New Zealand, S.W. Burstall and
E.V. Sale, to measure and photograph the notable and historic
trees in Otago.
Using a Suunto clinometer, he recognised these trees as being
of significant height. The then tallest tree was singled out
at 69.1m high and has since been known as the Frank Pepers
It was first measured in 1968 at 58.8m.
In 2004, Mark Roberts, an arborist from Otago Polytechnic,
climbed the Frank Pepers tree and measured it at 77m. He did
not want to use spikes that could lead to infection of the
tree, so, with a Harrison rocket, he had a line fixed and
secured over the first branch 41m above ground.
The second branch was reached using a throw ball and the rest
The Rotary Club of Dunedin has generously sponsored the
upgrade of the Saddleback Valley Track, which leads visitors
to the tree.
The track follows Orokonui Stream, descending steadily and
passing through beautiful podocarp forest and regenerating
kanuka/broadleaf forest before reaching the extraordinary
grove of eucalypts. The walk takes two to three hours return
from the visitor centre.
On Saturday, March 17, to celebrate the completion of the
upgrade of this track, Orokonui will run two guided tours, at
11am and 2pm, from the visitor centre to the tallest tree and
out through the ecosanctuary's bottom gate, where a bus will
pick up people from the Doc car park on Orokonui Rd and
return them to the visitor centre.
Alternatively, people can choose to return by walking back up
For bookings and inquiries, phone 482-1755.
A free talk on saddlebacks and their transfer into Orokonui
by Dr Ian Jamieson and a presentation to the Rotary Club of
Dunedin will be held at 1pm.
The cafe will be open.
• Chris Baillie, the general manager of the Orokonui
Ecosanctuary, has worked with the project since 2007, when
the fence was completed.