FLORA SURVEY REPORT by BMCS Plant Study Group
Overcliff Walking Track proceeds through three swamp areas which are all adversely impacted by bushwalking activities.
Our study site was the swamp that dried out for a period in 2013. It is located just past Lyrebird Lookout, when walking in an easterly direction towards Breakfast Point Lookout.
On the day of the site inspection the black peat substrate was compacted in track areas, with wood stepping blocks staying on the hard peat surface. There was a small flow of water across the track through the swamp. Erosion and loss of native flora were evident.
The geological structure of the swamp with permanent water flows, is consistent with Blue Mountains Swamp Communities that are listed as vulnerable / endangered communities.
The floristic composition and structure found in the area led to the conclusion that this Hanging Swamp meets the criteria of Blue Mountains Swamp in the Sydney Basin Bioregion under the TSC Act 1995 (NSW) and Temperate Highland Peat Swamp on Sandstone under the EP&BC Act 1999.
Mature plants of Acacia ptychoclada border the Hanging Swamp, with seedlings on the track edges, along with seedlings of Grevillea acanthifolia subsp. acanthifolia. It is probable that these species existed as mature plants in the swamp before the degradation by walkers. Both species are endemic to Blue Mountains swamps. Rupicola apiculata is also locally endemic.
The closure of the walking track has assisted the return of water flows, with seedling recruitment of shrub species and sedge growth with the dominance of Baumea rubiginosa.
The Listing of Blue Mountains Swamps as a Vulnerable Ecological Community states that, degradation from walking trails represents a moderate reduction in the ecological function of the community and is a threat to this Vulnerable Ecological Community.
The Listing of Temperate Highland Peat Swamps on Sandstone, states that outdoor recreational activities can result in hydrological changes with compaction of swamp soils, damage to vegetation and erosion, which constitute threats to this Endangered Ecological Community.
Plant Study Group recommends that threat abatement measures are instigated, such as the installation of boardwalks through all wet areas before the walking track is reopened. A boardwalk with educational signage will increase public awareness of endangered ecosystems and contribute to conservation of our National Parks into the future.
The unique threatened ecological swamp community along this southern escarpment warrant protection of the highest order, as it is in Blue Mountains National Park, Sydney Water Catchment and the Greater Blue Mountains World Heritage Area.
[Meredith Brownhill 9th May, 2014. BMCS Plant Study Group ]