Ecological Values and Conservation Significance of Crown Land Adjoining Black Hill Conservation Park

Ecological Values and Conservation significance of Crown Land adjoining Black Hill Conservation Park Report compiled by Dr Wendy Stubbs, Luke Price and Janine Kraehenbuehl September 2013 Executive summary Recent preliminary surveys of plants, birds, amphibians and reptiles on two parcels of crown land adjoining Black Hill Conservation Park have revealed a quality suite of species not recorded elsewhere in the state. The addition of these two parcels of land to Black Hill Conservation Park would be significant as it would greatly increase the viability of local plant and animal populations and thus the capacity of the reserve to conserve species into the future. Particular qualities to note include: Breeding population of Mt Lofty Ranges chestnut-rumped heathwrens – a regionally endemic species listed as endangered under the EPBC Act and one of the states most threatened birds. Unusually high diversity of reptiles not seen elsewhere in the region. A unique assemblage of plant species not seen anywhere apart from on these two parcels of crown land due to the unusual presence of limestone bedrock. Stands of ancient grass trees which are expected to predate colonisation. Forty four plant species threatened at a state or regional level (with additional surveys likely to detect more). Looking east along Gorge road on crown land parcel F171413 A91. Photo: S. Collard. Uniqueness of these parcels The area encapsulated within the crown land parcels F107799 A6 and F171413 A91 (Figure 1) is unique in the region as it represents the only area of a dryland community within a high rainfall zone observed within the state. This area consists of rocky shallow alkaline soils across mainly north facing slopes. While the Adelaide Mount Lofty Ranges (AMLR) typically has acidic soils, these two parcels of land are dominated by limestone, a feature not observed within Black Hill Conservation Park itself, and not conserved within the reserve system anywhere else within this region. The distinctiveness of these two parcels therefore represent a critical addition to Black Hill Conservation Park. Figure 1: Selected broad vegetation associations within crown land parcels F107799 A6 and F171413 A91. Area A = drooping sheoak and yacca heath, Area B = drooping sheoak woodland with grey Trymalium and Mount Lofty grass trees, Area C = grey Trymalium shrubland, Area D = grey Trymalium and dryland teatree shrubland, Area E = drooping sheoak and mixed Eucalyptus woodland, Area F = Mount Lofty grass tree with sticky hop bush low open shrubland, Area G = mallee box woodland , and Area H =. silver banksia low woodland with drooping sheoak, See Price et al. (2013a) for a full description of each vegetation association. Large expanses of these parcels of land are dominated by grey Trymalium (Trymalium wayae) shrub-land (Figure 2) with a variety of co-dominant plants including dryland tea tree (Melaleuca lanceolata),drooping sheoak (Allocasuarina verticillata) and grass trees (Xanthorrhoea semiplana ssp. semiplana and Xanthorrhoea quadrangulata) (Figure 1). This association of species is extremely rare and this crown land represents the only area within the AMLR region where it exists. While some of the same species are found further north within the Flinders Ranges, the vegetation association found within this crown land differs significantly from similar vegetation associations in the Flinders Ranges making this area quite unique (Brewer 2001). This association contains several species that have limited distribution at a state, district and local level, and it contains many species typically found within mallee systems which are not common in the AMLR (Brewer 2001). Figure 2: A patch of grey Trymalium shrubland containing Mount Lofty grass-trees in F171413 A91. Photo: L. Price Scattered across these two parcels of land are numerous stands of large grass trees, with some individuals over 6 feet in height (Figure 3). Due to the slow growing nature of these plants, it is believed that these individuals would be more than 100 years old, and they are likely to predate European settlement (H Vonow 2013, pers. comm. SA State Herbarium). While the two species of grass trees are also found within Black Hill Conservation Park, the individuals found within the crown land are significantly larger than any found within the park and are larger than any preserved anywhere else in this region or the Flinders Ranges. Figure 3: A stand of Mount Lofty grass-trees which stand over 6 ft tall in F171413 A91. Photo: L. Price. Several other community types found within these parcels of land are considered threatened at a state and regional scale. For example, Banksia marginata grassy low woodland which is found in the northernmost tip of F107799 A6 (area H on figure 1) is considered endangered across the state and is very significant for this region (Wilson and Bignall 2009). Mallee Box (Eucalyptus porosa) grassy woodland which is found in the north western section of F107799 A6 (area G on figure 1) is also considered threatened within the region. The lower drainage lines of F171413 A91 contain redgum (Eucalyptus camaldulensis) grassy woodlands while the ridge top in the eastern section of F107799 A6 consists of SA blue gum (Eucalyptus leucoxylon) grassy woodland (Brewer 2001). While these communities are not listed as threatened, grassy woodlands per se are particularly under-represented in the AMLR. Grassy woodlands used to occupy 47% of this region, with only 7% of this area now remaining (representing 27% of the remnant total). Despite historically covering nearly half of the Mount Lofty Ranges, only 3,709 ha is currently under formal protection (14% of the remaining 7%) (DEH 2009). Due to this disproportionate clearance and the limited extent formally protected, a DENR publication identifies both grassy woodlands and shrublands as two of the three most important community types for formal protection (out of 13 community types). Birds While extensive fauna surveys have not yet been conducted across this crown land, an initial bird survey undertaken by NCSSA in September 2013 identified 41 species of native bird utilising this site. Observations of the habitats across this area suggest another sixteen species are likely to inhabit this area and may well be detected if subsequent surveys were undertaken at other times of the year (Collard 2013, J. van Weenen 2013, pers. comm.). The vegetation found throughout these two parcels of land are dominated by dry low open shrubs. This open low shrubby habitat is particularly important for a suite of birds that is found along the dry ridge tops along the spine of the Mount Lofty Ranges, and due to the limited availability of this habitat is now in decline. Of the forty one species observed during the spring 2013 bird survey, six species had federal, state or regional conservation ratings (Table 1). Nine of the species likely to be detected if more surveys were undertaken are also considered in decline within this region (including elegant parrot, sacred kingfisher, white-naped honeyeater, and dusky woodswallow), with one species being considered rare across the state (scarlet robin). All of these species have shown marked declines in response to fragmentation and modification in the highly fragmented and modified Mount Lofty Ranges landscape (Paton et al. 1994). Table 1. Threatened bird species recorded in the study area during the survey in September 2013. Taken from Collard (2013). E = endangered, V = vulnerable, R = rare, U = uncommon. EPBC ratings range from critically endangered, endangered to vulnerable; State ratings range from endangered, vulnerable to rare and AMLR ratings range from endangered, vulnerable, rare to uncommon (Wilson and Bignall 2009). Species EPBC SA AMLR Chestnut-rumped heathwren E E V Yellow-tailed black-cockatoo V V Peregrine falcon R R Fan-tailed cuckoo V Shining bronze-cuckoo R Yellow-rumped thornbill U Mount Lofty Ranges Chestnut-rumped heathwren – endangered under EPBC Act The Mount Lofty Ranges Chestnut-rumped heathwren which is listed as endangered under both the Commonwealth Environment Protection and Biodiversity Act 1999 (second most threatened rating) and the South Australian National Parks and Wildlife Act 1972 (highest threat rating), has been recorded on both of these parcels of land (Collard 2013). This subspecies, Hylacola pyrrhopygia parkeri (Figure 4), is only found within the Mount Lofty Ranges, and the preservation of this species is one of the region’s highest conservation priorities, as fewer than 1,000 individuals are believed to remain. Unfortunately this species appears to be experiencing ongoing decline, with a reduction in total population from 2,500 to 1,000 over seven years (2000 to 2007). The primary cause of this decline is believed to be habitat loss and fragmentation outside of the reserve system (Long and Bentley 2010). Therefore, preserving all remaining suitable habitat for this species is critical to ensure their survival. Figure 4: Juvenile Mount Lofty Ranges chestnut-rumped heathwren in Scott Creek Conservation Park. Photo: D. Moise. Two observations were made of Mount Lofty Ranges chestnut-rumped heathwren within the subject land, both within dense shrubby habitat in rocky areas with Trymallium wayi, Allocasuarina verticillata and Dodonea viscosa the dominant plant species. This species occupies a very small home range so as one of the two birds observed was a juvenile, it is evident that chestnut-rumped heathwren are breeding within this subject area. Previous studies have identified that the largest population of this species exists within the area from Black Hill Conservation Park to Cleland Conservation Park (Pickett 2007), making this area a priority for conservation of this species. Moreover, these parcels of crown land provide an extremely important linkage between populations of this species found in Anstey Hill Recreation Park to the north and populations within Black Hill and Moriatla Conservation Parks to the south (Collard 2013). An EPBC Act referral would need to be lodged with the Commonwealth Government before any modifications could be made to this area.

Load more