Cunninghamia 1 (1): 7-22 (1981) 
7 
VEGETATION OF UPPER MANGROVE CREEK, WYONG, 
NEW SOUTH WALES 
D. H. Benson 
(Accepted for publication 20.12.1979) 
ABSTRACT 
Benson, D. H. (National Herbarium of New South Wales, Royal Botanic Gardens, 
Sydney, New South Wales, Australia 2000) 1981. Vegetation of Upper Mangrove Creek, 
Wyong, New South Wales. Cunninghamia 1 (1): 7-22. In a survey of 9 000 ha of 
the upper catchment of Mangrove Creek, Wyong, New South Wales, four types of 
vegetation, distinguished structurally and Horistically, are described and related to 
physiographic and geological variation. On Hawkesbury Sandstone, Eucalyptus eximia- 
E. gummifera-E. punctata woodland occurs on ridgetops and N to W facing slopes, while 
Angophora cost ala- Eucalyptus piperita open-forest occurs on S to E facing slopes and 
in sheltered gullies. In valleys cut into Narrabeen Group shales and sandstones, 
Eucalyptus tereticornis-E. eugenioides open-forest occurs on dry aspects of the lower 
slopes while Eucalyptus deanei-Angophora floribunda tall open-forest occupies the 
lower slopes on sheltered S facing slopes and on Recent alluvium. The value of “forest 
types” for the description and mapping of vegetation is discussed. 
INTRODUCTION 
The vegetation of the catchment of the planned Mangrove Creek Dam is 
described here. The catchment covers approximately 9 000 ha of the headwaters 
of Mangrove Creek (lat 33° 10' S, long 151° 10' E) which rises approximately 30 km 
north-west of Wyong, and flows south to join the Hawkesbury River at Spencer. 
This area was included in Pidgeon’s (1941) general survey of the vegetation of the 
Central Coast of New South Wales and the vegetation assigned to two broad plant 
Associations, the Mixed Eucalyptus Forest Association and the Eucalyptus saligna- 
E. pilularis Association. She recognized that there was considerable variation within 
these Associations and suggested that within them a number of “forest types” could, 
with further work, be recognized. The opportunity arose to see whether the vege¬ 
tation could be satisfactorily described and mapped in terms of “forest types” in a 
catchment where much of the vegetation was, at the time, relatively little altered 
from its natural state. 
The catchment area is on part of the Triassic Hawkesbury Sandstone plateau 
which covers much of the Sydney region (N.S.W. Department of Mines, 1966). 
Here the plateau has been dissected by Mangrove Creek and its tributaries, which 
have cut deep valleys through the sandstone to expose the softer shales and sandstones 
of the underlying Narrabeen Group, also of Triassic age. On the floors of the valleys 
are alluvial flats. Included in the catchment area is a small outcrop of Tertiary 
basalt, which has been cleared of its original native vegetation. 
Climatic data for Cessnock, a similar distance from the coast as the catchment 
area and approximately 45 km north, are given in Figure 1. 
SURVEY METHOD 
Colour aerial photography (approximate scale 1:16 300) was used to map 
recognizable units or “phototypes”. Vehicular and foot traverses were made in 
April and August 1976 to field-check mapped boundaries and to record detailed 
data from ten sites. These sites were chosen from the aerial photography to sample 
the different phototypes recognized and the range of variation within each phototype. 
Detailed recording sites were 20 x 20 m square quadrats in which all vascular plant 
species present were recorded. All stems with a diameter (d.b.h.) greater than 5 cm 
were measured, and the density and basal area for each site determined. Projected 
canopy foliage cover was measured at 50 points within the site, using a vertical 
sighting tube with cross-wires. Aspect and slope were recorded and an estimate of 
general canopy height was made. 
