Targeted Vegetation Survey of Floodplains and Lower Slopes on the ...

CCA08 Far North Coast <strong>Targeted</strong> <strong>Vegetation</strong> <strong>Survey</strong>
The vegetation <strong>of</strong> the estuarine <strong>and</strong> alluvial plains
is a complex continuum <strong>of</strong> floristic distribution <strong>and</strong>
abundance with gradual replacement <strong>of</strong> species as
salinity <strong>and</strong> inundation decreases, mixed with local
differences in overstorey <strong>and</strong> understorey based on
microhabitat variation in tidal influence <strong>and</strong> the input
<strong>of</strong> sediment from adjoining lithologies. The vegetation
<strong>of</strong> the coastal barrier s<strong>and</strong>s was linked to topographic
position, depth <strong>of</strong> the water-table, fire frequency
<strong>and</strong> degree <strong>of</strong> exposure to coastal onshore winds.
<strong>Vegetation</strong> <strong>of</strong> the lowl<strong>and</strong>s was influenced by geological
parent material, soil fertility, aspect <strong>and</strong> the influence
<strong>of</strong> subsaline soils. The survey found that coarse-scale
intuitive approaches used for mapping missed some <strong>of</strong>
the variation delineated by floristic sampling.
An assessment <strong>of</strong> the distribution <strong>of</strong> communities
in the study area found that most poorly reserved
communities were located on the alluvial plain
(16 communities), the estuarine plain (12), lower
slopes on basalt <strong>and</strong> sedimentary geology (11), <strong>and</strong>
coastal barrier s<strong>and</strong>s (2). The reservation <strong>of</strong> alluvial,
estuarine plain <strong>and</strong> lowl<strong>and</strong> vegetation communities is
particularly poor in the coastal lowl<strong>and</strong>s <strong>of</strong> the Tweed,
Brunswick <strong>and</strong> Richmond Rivers.
Thirty seven (37) <strong>of</strong> the 62 vegetation communities
delineated have structural <strong>and</strong> floristic characteristics
which relate to nine endangered ecological
communities: Coastal saltmarsh; Freshwater wetl<strong>and</strong>s
on coastal floodplains; Swamp sclerophyll forest on
coastal floodplains; Swamp Oak floodplain forest;
Subtropical coastal floodplain forest; Lowl<strong>and</strong>
rainforest on floodplain; Themeda grassl<strong>and</strong> on
seacliffs <strong>and</strong> coastal headl<strong>and</strong>s; <strong>and</strong> Littoral rainforest.
The survey improved the knowledge <strong>of</strong> the floristic <strong>and</strong>
structural composition <strong>and</strong> environmental influences
on these endangered ecological communities.
Nearly 300 records <strong>of</strong> 50 significant taxa were made
during the survey, including 39 threatened plants
species, eleven ROTAP <strong>and</strong> a number <strong>of</strong> other rare
species <strong>and</strong> those at the limit <strong>of</strong> their distribution:
Significant taxa recorded included (in alphabetical
order by threat category): Endangered: Acronychia
littoralis, Cassia brewsteri var. marksiana, Davidsonia
jerseyana, Dendrobium melaleucaphilum, Dendrocnide
morioides, Diospyros mabacea, Diospyros major var.
ebenus, Diploglottis campbellii, Elaeocarpus sedentarius,
Elaeocarpus williamsianus, Eleocharis tetraquetra,
Endi<strong>and</strong>ra muelleri subsp. bracteata, Geodorum
densiflorum, Gossia fragrantissima, Grevillea hilliana,
Marsdenia longiloba,Oberonia complanata, Ochrosia
moorei, R<strong>and</strong>ia moorei, Xylosma terrae-reginae.
Vulnerable: Acacia bakeri, Archidendron hendersonii,
Bosistoa transversa, Corokia whiteana, Cryptocarya
foetida, Desmodium acanthocladum, Endi<strong>and</strong>ra floydii,
Endi<strong>and</strong>ra hayesii, Fontainea australis, Hicksbeachia
pinnatifolia, Lepiderema pulchella, Lindsaea brachypoda,
Macadamia tetraphylla, Oberonia titani, Peristeranthus
hillii, Persicaria elatior, Syzygium moorei, Tinospora
tinosporoides. ROTAP: Acianthus amplexicaulis
(2RC-), Acronychia baeuerlenii (3RC-), Archidendron
muellerianum (3RCa), Argophyllum nullumense (3RCa),
Arthrochilus prolixus (2K), Callerya australis (3RC),
Cordyline congesta (2RC-), Cupaniopsis newmanii
(2RC-), Endi<strong>and</strong>ra globosa (2RC-), Gahnia isignis
(3RCa), Hicksbeachia pinnatifolia (3RC-), Rhodamnia
maideniana (2RC-), Trichosanthes subvelutina (3RC-).
Other significant species: Brunoniella spiciflora (rare in
NSW), Dianella brevipedunculata (rare in NSW), Scleria
levis rare in NSW, Sida cordifolia (rare in NSW).