Citizen Science at the Arboretum

Quercus macrocarpa, burr Oak, Forest 18

By Roger Hnatiuk June 2020

forest 18The trees in Forest 18 were sourced from street trees in National Circuit, Forest, ACT.  Seeds for those trees were sourced from the ‘Botanical Gardens, Melbourne’.  Five out of 266 trees in the Forest are unlikely to be Q macrocarpa, based on an analysis of their leaves, branchlets and fruits.  Four of these are likely to be hybrids from crosses with Q bicolor, also occurring on National Circuit. 

These two species are known to readily hybridise both in nature and in cultivation.  One tree appeared quite different in growth form from either of these two species, but what it is will need to await the production of leaves next year, and of fruits.

View the full report.

Quercus engelmannii, mesa oak

By Roger Hnatiuk, Joanne Maples, Maggie Hawes  June 2020

forest 21The population of oaks in Forest 21 at the National Arboretum Canberra, though sourced from trees of Quercus engelmannii, mesa oak, in Caladenia Street, O’Connor, ACT, are clearly a hybrid complex of that species and Q lobata, valley oak, which occurs in the adjacent Clianthus Street.  These two species are wind pollinated and known to hybridise.  The leaf and acorn shapes from the Arboretum show a range of variation that encompasses both of these two species.

The mesa oak forest was originally selected for planting as a ‘forest’ because it was listed as an endangered species in the IUCN Red List.  However, because seed could not be sourced from the wild, the trees, which turned out to be a rich diversity of hybrids, has provided the focus for telling new stories about species evolution and how hybridity can play a role.

View the full report.


In 2013 we monitored a number of sites at the Arboretum on a weekly basis throughout spring.
Thanks to our regular site visits, we recorded the sounds of the Spotted Burrowing Frog (Neobatrachus sudellii), which is not often heard in the ACT.

This species was detected in mid-September 2013, after heavy rain falls at two of the Arboretum sites. 

A summary of the results are now available on the Frogwatch website:
Click through: Frogwatch/census, then scroll down to any of four sites (NAD011, NAD034, NAD036 or NAS100); click on the site and the observations will open.

Tree Mapping and Counting Project

Himalayan Cedars

The new forest plantings at the Arboretum have maps showing the locations of each tree. These maps are a critical component of the sampling program used to measure the growth of trees. The 'old' forests of the Arboretum do not have any extant maps and this makes developing the statistical tree sampling scheme difficult. Also, these forests cannot be mapped using aerial photography because their canopies are not regular enough in shape to allow the position of the trunks to be recorded. To remedy this shortcoming of the 'old' forests, new maps are being prepared.

The work involved walking each forest row, recording the position of each:

  • * living tree and how many trunks the tree had to about iiii2 m above ground level;
  • * dead tree;
  • * gap in the grid where a tree could have been in the iiiipast; and
  • * significant footpath and vehicular track.

See the May 2014 Newsletter article, pages 6-8

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