10 
Cunninghamia 
Vol. 1 (1): 1981 
TABLE 1 
Relationship between mapped units, plant communities, geology and physiography. 
Mapped unit 
Plant community 
Geology 
Physiography 
Tall open-forest/open- 
forest 
Eucalyptus deanei- 
Angophora floribunda 
Tall open-forest 
Recent 
alluvium, 
Narrabeen 
Group 
Sheltered valleys, S to SW 
facing slopes. 
Eucalyptus tereticornis- 
E. eugenioides 
Open-forest 
Narrabeen 
Group 
Lower slopes of hills, drier 
aspects. 
Angophora costata- 
Eucalyptus piperita 
Open-forest 
Hawkesbury 
Sandstone 
Sheltered gullies, S to E 
facing slopes. 
Woodland 
Eucalyptus eximia-E. 
gummifera-E. punctata 
Woodland 
Hawkesbury 
Sandstone 
Ridgetops and exposed 
slopes, N to W facing 
slopes. 
The main tree species are Eucalyptus deanei (Deane’s Gum) a tall straight 
smooth-barked tree, abundant in sheltered gullies, and Angophora floribunda (Rough- 
barked Apple), a rough-barked tree with twisted branches, generally shorter than 
E. deanei and more common on alluvial flats. Other canopy trees found are 
Eucalyptus tereticornis (Forest Red Gum) and E. acmenoides (White Mahogany). 
Below the main canopy may be a small-tree stratum about 8 m high of Casmrina 
torulosa (Forest Oak) and Acacia filicifolia (Fern-leaf Wattle). Acacia filicifolia is 
particularly abundant where the tree canopy has been opened and forms dense 
thickets in and around clearings. Ground cover is a dense layer of ferns and grasses, 
and appears to have been grazed and regularly burnt for many years. Common 
ground species are Adiantum aethiopicum, Pteridium esculentum, Doodia aspera, 
Culcita dubia, Imperata cylindrica and Dichondra repens. Hibbertia scandens, a 
small trailing shrub, is often abundant. 
Boundaries with the drier Eucalyptus tereticornis-E. eugenioides open-forest 
are transitional. 
Remnants of the Eucalyptus deanei-Angophora floribunda tall open-forest are 
found also along Mogo and Wyong Creeks. This vegetation type was probably 
originally widespread along most creeks in the area. Samples have been preserved 
in Dharug National Park (Matthew, 1973) and along Mooney Mooney Creek in 
Brisbane Water National Park. 
Eucalyptus tereticornis-Eucalyptus eugenioides OPEN-FOREST 
On the drier northerly and westerly aspects on exposures of the Narrabeen 
Group, the Eucalyptus deanei-Angophora floribunda tall open-forest is replaced by 
f" open-forest of Eucalyptus tereticornis (Forest Red Gum) and E. eugenioides 
(Thin-leaved Stringybark). This community ranges in height from 12 to 20 m and 
includes a number of other tree species such as E. acmenoides (White Mahogany), 
E. punctata (Grey Gum) and E. crebra (Narrow-leaved Ironbark). E. deanei and 
A. floribunda may be present on moister sites. Smaller trees of Casuarina torulosa 
and sapling eucalypts to 8 m with a discontinuous shrub layer of Persoonia linearis 
and Jacksonia scoparia form the understorey. Ground cover is open with grasses 
and small shrubs up to 0.5 m. Common species are Pteridium esculentum , Imperata 
cylindrica and Hibbertia scandens. 
Boundaries with E. deanei-A. floribunda tall open-forest on alluvial flats are 
transitional, but are abrupt with the communities found on Hawkesbury Sandstone. 
