98 
Cunninghamia 
Vol. 1 (1): 1981 
Styphelia laeta var. latifolia (Epacridaceae), found in the dense shrubby under¬ 
storey of open-forest to low open-forest on Hawkesbury sandstone slopes (Com¬ 
munity 4), in low open-forest of plateau tops with earthy soils (Community 4P) and 
in low woodland (Community 6). This variety is known only from the Gosford- 
Ourimbah-Kulnura-Peats Ridge area. Another variety of this species, S. laeta var. 
laeta, was found in the south of the Park. There appears to be a possibility of 
hybridization between this variety and Styphelia longifolia (J. M. Powell, National 
Herbarium, pers. comm.); this requires further investigation. 
Patches of hybrids between Conospermum taxifolium and C. longifolium subsp. 
longifolium (Proteaceae) occur in the Park, between Mooney Mooney Creek and 
Girrakool. (D. McGillivray, National Herbarium, pers. comm.). 
If populations of these restricted species are disturbed or damaged in the Park 
and its environs then recovery is unlikely as local propagule sources are rare or 
unavailable. 
Plant Community Distributions 
The distribution of the plant communities primarily reflects geological, soil, 
drainage and aspect differences. Several of the communities are uncommon in the 
area and/or have very restricted distributions, and some are endangered by man’s 
activities. 
The southern parts of the study area south of the Pacific Highway, are dominated 
by ridges and slopes of Hawkesbury Sandstone; open-forest and closed to open- 
scrub (Communities 4 and 8) dominate these areas, often forming a continuum. 
There are occasional rock outcrops with pockets of heath (Community 9), each of 
very limited extent, and some GYz/w/'a-dorninated sedgelands (Community 12) in 
‘swampy’ valleys lining the watercourses. Both communities are uncommon in 
this area. The open-forest (Community 4S) is an unusual feature of the south of 
the Park. This community is botanically and ecologically interesting; it is floristi- 
cally quite distinctive and appears to be restricted to remnant shale outcrops in 
Hawkesbury Sandstone. 
A different group of plant communities predominate in the north of the study 
area. On the ridgetops and plateaux are deep yellow earth soils with open-forest 
(Community 4P). Since this soil is favoured by orchardists only small pockets of 
vegetation remain. An isolated patch of this community occurs in the south of 
the Park along the Patonga road near Warrah Trig. Sedgelands (Community 12) 
seem to be far more extensive in the north and are particularly common on the 
scarp of the Hunter Range east of Somersby. They rely heavily on natural drainage 
patterns and any changes to these will greatly affect this community. Many sedge¬ 
lands occur close to farmed areas and are not within the Park. 
The vegetation of valleys which cut deep into Narrabeen Group strata is better 
developed in the northern part of the area. These protected moist valleys support 
closed-forest (Community 1) and open-forest with a moist understorey (Community 
2B). The main valleys are those of Mooney Mooney Creek and Narara Creek (in 
Strickland State Forest). The closed-forest in Strickland State Forest is particularly 
rich in rainforest species. Drainage from farms into Communities 1 and 2B will 
bring increased nutrients (from fertilizers and sediment), possibly some pesticides 
and herbicides, and seeds. Weed problems are likely to increase, particularly along 
creek lines, e.g. into upper Mooney Mooney Creek. 
The coastal and estuarine communities (3, 5, 7, 10 and 11) are not extensive and 
have been greatly disturbed by urban development. Very few relatively undisturbed 
areas remain, and few of these are within the Park. The most extensive areas of 
mangroves (Community 7) left in the study area occur along Patonga and Mooney 
Mooney Creek. In Native Dog Bay on Mooney Mooney Creek, mangroves have 
been affected by deposits of sediments from erosion (following highway construction) 
