WEST KIMBERLEY PLACE REPORT - Department of Sustainability ...

Wheeler et al. (1992) identified 290 species with high endemism, or that are
insufficiently known, within the Northern Province. Later, Beard et al. (2000) argued
that the Northern Province actually had a relatively low rate of endemic species at
14.3 per cent (306 species), far fewer than the species endemic to the similarly sized
Southwest Province. The WA Herbarium state taxa inventory (DEC 2010) calculated
percentages of endemic taxa based on plants entirely restricted to their province as
compared to the other two provinces in WA: Northern (59.2 per cent), Eremaean
(29.7 per cent) and Southwest (65.6 per cent). While this shows a high percentage for
the Northern Province (Kimberley), this state comparison is somewhat misleading
when taken nationally, as many of the Northern and Eremaean plants also grow in
other states, reducing the percentage of plant taxa that are truly endemic to these
regions. However, plants found in the southwest, which is isolated from other areas, is
clearly greater for plant endemism in real terms at a national scale.
Woinarski et al. (2006) identified the Northern Territory's plant endemism hotspot
(172 species) as being focused on the sandstone plateaus of west Arnhem Land. While
this figure is smaller than the Western Australian Northern Province (290 species in
35 million hectares) the west Arnhem Land region is significantly smaller in area (3.2
million hectares). A more scale appropriate comparison was provided by Petersen and
Watson (1998) who determined that the Top End of the Northern Territory (north of
16 ° S encompassing 31.6 million hectares) possesses 438 endemic plant species,
surpassing that of the Kimberley. By comparing endemic species on a per hectare
basis, the smaller Cape York Peninsula (13.5 million hectares) with 264 endemic
plant species (Abrahams et al. 1995) rivals both the Kimberley and Top End regions.
ANHAT analysis showed one of the nationally significant localised endemism centres
(tope 0.2 per cent for country) for Corymbia (bloodwoods) around the Windjana
Gorge and King Leopold Ranges Conservation Park, with a second, less significant
centre occurring around the Gibb River and Drysdale River stations. The presence of
a number of restricted species together, including Corymbia pedimontana, C. torta
and C. collina, is unusual in the context of Australian tropical savanna woodlands.
The North Kimberley IBRA region, which includes some of these centres, also was
shown to possess a high, but not nationally high, eucalypt endemism score in West
and others' (West et al. 2002) assessment. While ANHAT analysis showed there are
other, less significant areas of bloodwood endemism, including the southeast
Kimberley and Kakadu, the general pattern for savanna woodlands is for the upper
strata to be dominated by eucalypts (Eucalyptus and Corymbia) with very wide
ranging distribution patterns. The concentration of these endemics is likely a factor of
a more variable topography, endemism also being found within rugged west Arnhem
Land. Bloodwood species richness is by far greatest in the northwest of the Northern
Territory; coupled with strong endemism scores, the Northern Territory Corymbia
dominated woodlands are considered to be of greater national significance than those
found within the Kimberley. When considering eucalypts overall (Eucalyptus and
Corymbia combined), according to literature (West et al. 2002) and ANHAT analyses,
the nationally strongest scores are found in the southwest of Western Australia for
both richness and endemism.
ANHAT analysis also showed a significant endemism score in the Kimberley for
Fabaceae (peas), due the presence of restricted species in a range of genera, including
Indigofera, Desmodium, Dendrolobium, Cajanus and Tadehagi. While Fabaceae in
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