2022-09-06 P&E Agenda - Item 5 - Attachment 1 - Six Mile Creek Bridge Replacement Offset Report - TMR

2.2.1        Lowland Rainforest of Subtropical Australia Threatened Ecological
             Community

2.2.1.1      Ecological background
The Lowland Rainforest of Subtropical Australia TEC primarily occurs from Maryborough in Queensland to
the Clarence River in New South Wales. The TEC occurs on basalt and alluvial soils, including sand and
old/elevated alluvial soils as well as floodplain alluvia. It also occurs occasionally on historically enriched
rhyolitic soils and basaltically enriched metasediments. Lowland Rainforest mostly occurs in areas <300 m
above sea level. The TEC is moderately tall to tall (20 m to over 30 m), with a closed canopy cover (i.e.
≥70% cover). Tree species with compound leaves are common and leaves are relatively large (notophyll to
mesophyll). Typically, there is a relatively low abundance of species from the genera Eucalyptus, Melaleuca
and Casuarina. Buttresses are common, as is an abundance and diversity of vines (DSEWPaC 2011).
The canopy is often multi-layered, consisting of an upper, discontinuous layer of emergents, over the main
canopy and subcanopy. Below the canopy is an understorey of sparse shrubs and seedlings. The upper,
discontinuous layer includes canopy emergents that may be 40–50 m tall and have large spreading crowns.
Typically, non-rainforest species such as eucalypts and brushbox comprise <30% of canopy emergents
(DSEWPaC 2011). Patches of the Lowland Rainforest of Subtropical Australia TEC are generally small in
size (<10 ha) (DSEWPaC 2011).


2.2.1.2      Potential impact
The Lowland Rainforest of Subtropical Australia TEC was confirmed to be present within and immediately
adjacent to the proposed action (refer Figure 2.1). The TEC is associated with Six Mile Creek, where it is
analogous (in part) with the Queensland-based Regional Ecosystem 12.3.1.
Assessment of the condition of the Lowland Rainforest of Subtropical Australia TEC associated with the
proposed action, using the Queensland BioCondition Assessment methodology (Eyre et al., 2015) (refer
Appendix A; Section 4.3.2) was undertaken. Analysis indicates that the TEC has a BioCondition score of
51/100 and has a condition class of 3 (where 1 is highest condition and 4 is lowest condition). However,
noting this condition class, the patch still conforms with the “Patch B thresholds” as identified in the
Commonwealth Listing Advice on Lowland Rainforest of Subtropical Australia (Threatened Species Scientific
Committee (TSSC) 2011) (refer Appendix A; Section 4.3.3).
Approximately 0.173 ha of the Lowland Rainforest of Subtropical Australia TEC has been identified as being
contained within the area of direct disturbance associated with the proposed action (refer Figure 2.1).
An assessment of significance related to potential impacts upon the Lowland Rainforest of Subtropical
Australia TEC, as a result of the proposed action, has been undertaken in accordance with the Matters of
National Environmental Significance: Significant impact guidelines 1.1, Environment Protection and
Biodiversity Conservation Act 1999 (Significant impact guidelines 1.1) (Department of the Environment
(DotE) 2013) (refer Appendix A; Section 6.1.1).
In consideration of the direct removal of 0.173 ha of the Lowland Rainforest of Subtropical Australia TEC as
part of the proposed action, and in consideration of Significant impact guidelines 1.1 (noting that disturbance
thresholds are not contained within the guidelines), the proposed action will result in a reduction of the extent
of an ecological community. As per the Significant impact guidelines 1.1, this reduction in extent is likely to
result in a significant impact to the Lowland Rainforest of Subtropical Australia TEC.
Mitigation measures to reduce the severity of these impact induce the provision of direct, land-based offsets
(refer Section 3.2), clearing the minimum extent necessary for the proposed action, and management
measures to reduce edge-related impact from degrading areas that have been retained. Further detail
related to mitigation measures to reduce the potential impacts associated with the proposed action, are
provided within Section 3.2.




                            Project number 511784 File Six Mile Creek - Matters of National Environmental Significance Report 2021-12-03 Revision 1   17