Floristic Community Types

4. RESULTS

4.2 V EGETATION OF THE S TUDY A REA

4.2.1 Floristic Community Types

FCT 1: Mid Open to Sparse Shrubland of mixed Acacia species including A.

inaequilatera, A. colei var. colei and A. ancistrocarpa over Low Open Shrubland dominated by Acacia stellaticeps over Low Hummock Grassland dominated by Triodia epactia and/or T. lanigera on red sandy loams on lower slopes, flats and plains.

Total Area: 1 431 ha

Percentage of Study Area: 27.4 %

Sampling: 11 Quadrats (MD01, MD02, MD03, MD04, MD05, MD06, MD09, MD10, MD12, MD13, MD20)

Common taxa recorded within each stratum:

Stratum Descriptor Taxa

Mid Stratum 1 Mid Open to Sparse Shrubland (Shrubs 1-2 m)

Acacia inaequilatera, A. colei var. colei; A.

ancistrocarpa Mid Stratum 2 Low Open Shrubland

(Shrubs <1 m) Acacia stellaticeps, Pluchea tetranthera, Sida sp.

Pilbara (A.A. Mitchell PRP 1543)

Lower Stratum Low Hummock

Grassland (Hummock Grasses <0.5 m)

Triodia epactia, Triodia lanigera

Indicator Taxa: Acacia stellaticeps

Landform Types: Plains, Lower Slopes, Minor Basin, Flats Soil Types: Red sandy loams

FCT 1 was mapped in the north-eastern section of the study area, and also through the central section, on flat plains and lower slopes (Figure 3). The taller shrub layer (mid stratum 1) varied in composition, with Acacia taxa generally comprising this layer, however this layer was absent altogether at several quadrats. The lower shrub layer (mid stratum 2) was consistently dominated by Acacia stellaticeps. The hummock grass layer (lower stratum) of most quadrats was dominated by Triodia epactia, however several were dominated by Triodia lanigera, with the two taxa co-dominating at one site (Plate 4).

A total of 23 vascular plant taxa were recorded in quadrats grouped in FCT 1 (Appendix K). No

introduced or conservation-significant flora taxa were recorded in this FCT. Species richness per

quadrat within FCT 1 was 6.6 ± 1.9. FCT 1 was not dominated by taxa from any particular taxon

group (Appendix M). The sole indicator taxon for FCT 1 was Acacia stellaticeps (Appendix N),

a common and widespread species throughout the Pilbara which generally prefers red sandy soils

on plains.

Plate 4: Photograph of FCT 1 (Quadrat MD09)

FCT 2: Low Isolated Trees of Corymbia zygophylla or Corymbia hamersleyana over Mid Sparse Shrubland of mixed Acacia species including A. ancistrocarpa, A.

inaequilatera, A. sericophylla and A. acradenia over Low Sparse Shrubland of mixed species including Acacia stellaticeps, Pluchea tetranthera, Corchorus elachocarpus and Sida arenicola over Low Hummock Grassland dominated by Triodia lanigera and/or Triodia schinzii on red sandy loams on lower slopes, flats and plains.

Total Area: 3 271 ha

Percentage of Study Area: 62.6 %

Sampling: 23 Quadrats (MD07, MD08, MD11, MD14, MD15, MD16, MD17, MD18, MD19, MD25, MD27, MD28, MD32, MD33, MD35, MD38, MD39, MD40, MD41, MD42, MD47, MD48, MD49)

Common taxa recorded within each stratum:

Stratum Descriptor Taxa

Upper Stratum 1 Low Isolated Trees Corymbia zygophylla, C. hamersleyana Mid Stratum 1 Mid Sparse Shrubland

(Shrubs 1-2 m) Acacia ancistrocarpa, A. inaequilatera, A.

sericophylla; A. acradenia Mid Stratum 2 Low Sparse Shrubland

(Shrubs <1 m) Acacia stellaticeps, Pluchea tetranthera, Corchorus elachocarpus, Sida arenicola, Indigofera monophylla, Bonamia rosea, Senna glutinosa subsp.

glutinosa

Lower Stratum Low Hummock

Grassland (Hummock Grasses <0.5 m)

Triodia lanigera, Triodia schinzii

Indicator Taxa: Acacia ancistrocarpa, Bonamia linearis Landform Types: Plains, Lower Slopes, Flats

Soil Types: Red sandy loams

FCT 2 was mapped over much of the study area, including on the plains and lower slopes

surrounding Mount Dove (Figure 3). A tree layer (upper stratum 1) was often present, and

always consisted of one of either Corymbia zygophylla or C. hamersleyana. The taller shrub

layer (mid stratum 1) varied in composition between quadrats; Acacia taxa generally comprised

this layer, with A. ancistrocarpa being most commonly recorded. The lower shrub layer (mid

stratum 2) was not dominated by any particular taxon and was the most species-diverse layer,

however several taxa, including Acacia stellaticeps, Pluchea tetranthera, Corchorus

elachocarpus and Sida arenicola were consistently present. The hummock grass layer (lower

stratum) of most quadrats was dominated by Triodia lanigera, however several were co-

dominated or dominated by T. schinzii, with one unusual quadrat dominated by T. epactia (Plate

5).

A total of 54 vascular plant taxa were recorded in quadrats grouped in FCT 2 (Appendix K). No introduced taxa were recorded, however the conservation-significant flora taxon Heliotropium muticum (P1) was recorded only in this FCT. Species richness per quadrat within FCT 2 was 13.7 ± 2.7. FCT 2 was dominated by taxa from taxon group 2, with taxon group 7 also well represented (Appendix M). Indicator taxa for FCT 2 were Acacia ancistrocarpa and Bonamia linearis (Appendix N), both of which are common taxa in the Pilbara on sandy soils on plains.

Plate 5: Photograph of FCT 2 (Quadrat MD16)

FCT 3: Low Sparse Shrubland of mixed species including Pluchea tetranthera, P.

ferdinandi-muelleri and Acacia stellaticeps over Low Hummock Grassland of Triodia lanigera and Triodia schinzii on red sandy loams on lower slopes, flats and plains.

Total Area: 126 ha

Percentage of Study Area: 2.4 % Sampling: 2 Quadrats (MD36, MD37) Common taxa recorded within each stratum:

Stratum Descriptor Taxa

Mid Stratum Low Sparse Shrubland

(Shrubs <1 m) Pluchea tetranthera, P. ferdinandi-muelleri, Acacia stellaticeps, Gossipium australe, Solanum phlomoides,

Lower Stratum Low Hummock

Grassland (Hummock Grasses <0.5 m)

Triodia lanigera, Triodia schinzii

Indicator Taxa: Gossypium australe, Melaleuca glomerata, Pluchea ferdinandi-muelleri, Pluchea tetranthera, Solanum phlomoides, Triodia lanigera, Triodia schinzii

Landform Types: Plains, Lower Slopes, Flats Soil Types: Red sandy loams

FCT 3 was mapped only on an outwash flat to the west of Mount Dove (Figure 3). Only two quadrats grouped into this FCT; floristically it appears to be closely related to FCT 2, however may be influenced to a greater extent by nearby Mount Dove. Because of the low level of sampling in this FCT, the structure of this FCT cannot be described with certainty, however both quadrats consisted of a low shrub layer of mixed taxa (mid stratum) over a hummock grass layer (lower stratum) dominated by Triodia lanigera and T. schinzii (Plate 6).

A total of 20 vascular plant taxa were recorded in quadrats grouped in FCT 3 (Appendix K). No

introduced taxa or conservation-significant flora taxa were recorded in this FCT. Species

richness per quadrat within FCT 3 was 10.5 ± 2.1. FCT 3 was dominated by taxa from taxon

group 2 and 4, with taxon group 7 also well represented (Appendix M). Indicator taxa for FCT 3

(Appendix N) are all common taxa on sandy plains in the Pilbara.

Plate 6: Photograph of FCT 3 (Quadrat MD37)

Supergroup 2: Sparse Shrublands and Grasslands on mid – upperslopes and crests. The native species richness of FCTs within Supergroup 2 ranged from Low to Moderate (11+-1.8 species per quadrat to 21+-5.7species per quadrat).

Super-group 2 is comprised of FCTs 4 and 5, with FCT 5 being divided into two subtypes. It was generally mapped on rocky or stony areas, including hill slopes and crests. The structure of the vegetation frequently consisted of a mid sparse shrubland over low sparse shrubland over hummock grassland. The species richness of FCTs within Supergroup 2 ranged from 10.4 ± 2.6 species per quadrat (FCT 4) to 19.5 ± 3.5 species per quadrat (FCT 5a).

Topographical position appears to separate the FCTs in super-group 2, with FCT 4 being mapped on low rocky hills and outcrops, as well as the gentle footslopes of Mount Dove. FCT 5 was restricted to the steep upper slopes of Mount Dove and several hills to the west of the study area, and was characterised by taxa from taxon group 1, which contains a number of taxa found only on cliffs and outcrops (Appendix M). FCT 5 was split into subtypes 5a and 5b, with 5a being mapped only on Mount Dove, and 5b only recorded on hills to the west of the study area. FCT 5a was dominated by a different spinifex (Triodia) taxa to 5b, with 5b also possessing a mid sparse shrubland layer of Acacia taxa, which was not present in 5a.

FCT 4: Mid Sparse Shrubland of mixed species including Acacia inaequilatera, Grevillea wickhamii, A. ancistrocarpa and A. acradenia over Low Sparse Shrubland of mixed species including Corchorus elachocarpus, Indigofera monophylla and Goodenia stobbsiana over Low Hummock Grassland of Triodia epactia, Triodia wiseana or Triodia lanigera on shallow stony red-brown sandy loams on slopes and crests of low rises and hills.

Total Area: 375 ha

Percentage of Study Area: 7.2 %

Sampling: 11 Quadrats (MD21, MD22, MD23, MD24, MD26, MD29, MD30, MD31, MD34, MD43, MD46)

Common taxa recorded within each stratum:

Stratum Descriptor Taxa

Mid Stratum 1 Mid Sparse Shrubland

(Shrubs 1-2 m) Acacia inaequilatera, Grevillea wickhamii, A.

ancistrocarpa, A. acradenia, Hakea lorea subsp.

lorea Mid Stratum 2 Low Sparse Shrubland

(Shrubs <1 m) Corchorus elachocarpus, Indigofera monophylla, Goodenia stobbsiana, Senna notabilis, S. glutinosa subsp. x luerssenii

Lower Stratum Low Hummock

Grassland (Hummock Grasses <0.5 m)

Triodia epactia, T. wiseana. T. lanigera

Indicator Taxa: Heliotropium tenuifolium

Landform Types: Lower Slopes, Low Hills and Rises, Rocky Plains

Soil Types: Red or red-brown sandy loams with ironstone, quartz and granite stones and outcropping

FCT 4 was mapped on the footslopes of Mount Dove, over a low hill and associated slopes in the central part of the study area, and on several small areas of rocky outcrop or plain (Figure 3).

The taller shrub layer (mid stratum 1) consistently possess Acacia inaequilatera, however this taxon was usually co-dominant with Grevillea wickhamii and other Acacia taxa, with A.

ancistrocarpa being most commonly recorded. The lower shrub layer (mid stratum 2) was not dominated by any particular taxon and was the most species-diverse layer. The hummock grass layer (lower stratum) of most quadrats was dominated by Triodia epactia, however several were dominated by T. wiseana and/or Triodia lanigera (Plate 7).

A total of 45 vascular plant taxa were recorded in quadrats grouped in FCT 4 (Appendix K). No conservation-significant or introduced taxa were recorded in this FCT. Species richness per quadrat within FCT 4 was 10.4 ± 2.6. FCT 4 was dominated by taxa from taxon group 7 (Appendix M). The sole indicator taxon for FCT 1 was Heliotropium tenuifolium (Appendix N), a common and widespread taxon throughout the Pilbara which occurs in a variety of habitats (DEC 2010d).

Plate 7: Photograph of FCT 4 (Quadrat MD46)

FCT 5a: Low Sparse Shrubland of mixed species including Ptilotus obovatus, Aerva javanica and Capparis spinosa var. nummularia over Low Hummock Grassland of Triodia epactia and Eriachne mucronata on skeletal red sandy loams over massive ironstone outcropping on mid and upper slopes and crests of hills

Total Area: 21 ha

Percentage of Study Area: 0.4 % Sampling: 2 Quadrats (MD44, MD45) Common taxa recorded within each stratum:

Stratum Descriptor Taxa

Mid Stratum Low Sparse Shrubland

(Shrubs <1 m) Ptilotus obovatus, Aerva javanica, Capparis spinosa var. nummularia, Abutilon lepidum, Senna venusta, Solanum phlomoides, Senna glutinosa subsp.

glutinosa

Lower Stratum Low Hummock

Grassland (Hummock Grasses <0.5 m)

Triodia epactia, Eriachne mucronata, Enneapogon lindleyanus, Cymbopogon ambiguus

Indicator Taxa: Abutilon lepidum, Capparis spinosa var. nummularia, Cucumis maderaspatensis, Cymbopogon ambiguus, Enneapogon lindleyanus, Eriachne mucronata, Senna glutinosa subsp. glutinosa, Senna venusta, Solanum phlomoides

Landform Types: Upper Slopes, Crests

Soil Types: Skeletal Red sandy loam over massive ironstone

FCT 5a was mapped on the steep upper slopes and crest of Mount Dove only (Figure 3). The shrub layer (mid stratum) consisted of mixed species, including a number of taxa generally restricted to rocky cliffs. The hummock grass layer (lower stratum) was dominated by Triodia epactia, however in one quadrat Eriachne mucronata was co-dominant (Plate 8).

A total of 28 vascular plant taxa were recorded in quadrats grouped in FCT 5a (Appendix K). No

conservation-significant flora taxa were recorded in this subtype, however the introduced taxa

Aerva javanica and Cenchrus ciliaris were recorded, with Aerva javanica recorded widely on

Mount Dove (Figure 3), and forming a significant component of the shrub layer. Species

richness per quadrat within FCT 5a was 19.5 ± 3.5. FCT 5a was dominated by taxa from taxon

group 1 (Appendix M). Indicator taxa for FCT 5a (Appendix K) are all common taxa on rocky

areas in the Pilbara.

Plate 8: Photograph of FCT 5a (Quadrat MD45)

FCT 5b: Mid Sparse shrubland of Acacia arida and A. inaequilatera over Low Isolated Shrubs of Ptilotus obovatus over Low Hummock and Tussock Grassland of Triodia wiseana and Cenchrus ciliaris on skeletal red-brown sandy loams over massive ironstone outcropping on mid-upperslopes and crests.

Sampling: 4 Quadrats (MD50, MD51, MD52, 53) Common taxa recorded within each stratum:

Stratum Descriptor Taxa

Mid Stratum 1 Mid Sparse Shrubland

(Shrubs 1-2m) Acacia arida, A. inaequilatera, Hakea lorea, Grevillea pyramidalis subsp. leucadendron

Mid Stratum 2 Low Isolated Shrubs

(Shrubs <1 m) Ptilotus obovatus, Senna glutinosa subsp. glutinosa, Abutilon lepidum

Lower Stratum Low Hummock

Grassland (Hummock Grasses <0.5 m)

Triodia wiseana, Cenchrus ciliaris, Eriachne mucronata, Enneapogon lindleyanus, Cymbopogon ambiguus

Indicator Taxa: Acacia arida, Grevillea pyramidalis subsp. leucadendron, Triodia wiseana

Landform Types: Upper Slopes, Crests

Soil Types: Skeletal Red sandy loam over massive ironstone

FCT 5b was recorded on the steep upper slopes and crest of several hills to the west of the study area, however no mapping of the extent of this subtype was undertaken. In contrast to FCT 5a, a mid-height shrub layer (mid stratum) was present in all quadrats, and was co-dominated by Acacia arida and A. inaequilatera. No such defined low shrub layer existed as for FCT 5a, however isolated low shrubs occurred as a secondary mid stratum, of which Ptilotus obovatus was most common. The hummock and tussock grass layer (lower stratum) was dominated by Triodia wiseana, as opposed to T. epactia in FCT 5a, however Cenchrus ciliaris also formed a large component of this layer in most quadrats (Plate 9).

A total of 20 vascular plant taxa were recorded in quadrats grouped in FCT 5b (Appendix K).

No conservation-significant flora taxa were recorded in this FCT, however the introduced taxon

Cenchrus ciliaris was recorded, and formed a significant component of the hummock grass

layer. Species richness per quadrat within FCT 5b was 11.0 ± 1.8. FCT 5b was dominated by

taxa from sub-sections of taxon groups 1 and 7 (Appendix M). Indicator taxa for FCT 5b

(Appendix K) are all common taxa on rocky areas in the Pilbara.

Plate 9: Photograph of FCT 5b (Quadrat MD51)