Vegetation, fauna and groundwater interrelations in low nutrient temperate montane peat swamps in the upper Blue Mountains, New South Wales.

Abstract

Newnes Plateau Shrub Swamps are a series of low nutrient temperate montane peat swamps around 1100 m elevation in the upper Blue Mountains, west of Sydney (lat 33° 23' S; long 150° 13'E). Transect-based vegetation studies show a closely related group of swamps with expanses of permanently moist, gently sloping peatlands. Vegetation patterns are related to surface hydrology and subsurface topography, which determine local peat depth. While there is evidence that a group of the highest elevation swamps on the western side of the Plateau are more dependent on rainwater, the majority of swamps, particularly those in the Carne Creek catchment, and east and south of it, may be considered primarily groundwater dependent with a permanently high watertable maintained by groundwater aquifers. An integral part of the swamps are a number of threatened groundwater dependent biota (plants-Boronia deanei subsp. deanei, Dillwynia stipulifera, dragonfly-Petalura gigantea, lizard-Eulamprus leuraensis), which are obligate swamp dwellers. This association of dependence leaves the entire swamp ecosystem highly susceptible to threats from any loss of groundwater, the current major one being the impact of damage to the confining aquicludes, aquitards, aquifers and peat substrates as a result of subsidence associated with longwall mining. Impacts on the swamps may also result from changes to hydrology through damming of creeks, mine waste water discharge, increased moisture competition from pine plantations, recreational motorbike and off-road vehicle tracks and climate change.If these groundwater dependent ecosystems do not receive protection from activities such as longwall mining subsidence, significant ecological damage is unlikely to be avoided or able to be mitigated even where provisions of the Commonwealth Environment Protection and Biodiversity Conservation and NSW Threatened Species Conservation Acts apply to groundwater dependent swamps and biota. The importance of the highest elevation part of the Plateau for a number of restricted (some endemic) plant species is also discussed.

Testing the Power of a Wetland Vegetation Monitoring Survey Design to Detect Change Based on Visual Cover Estimates

“…Numerous wetlands occur on the plateau including those comprising the Endangered Ecological Community (Threatened Species Scientific Committee 2005) known as 'Newnes Plateau Shrub Swamp' (NPSS). NPSS are typically found on sloping drainage lines and are thickly vegetated, with no or very few trees, an understorey dominated by graminoids (Restionaceae, Cyperaceae, Poaceae, Xyridaceae and Juncaceae) and a sparse to dense shrub layer (Myrtaceae, Epacridaceae, Proteaceae) (DEC 2006;Benson and Baird 2012;Tierney et al 2015). Dense fern cover is also common in many NPSS, particularly toward the edges (authors' pers.…”

“…E.S. are relatively small, the combined effects of variability due to observer differences and quadrat placement may be large enough to warrant concern, particularly for variables such as exotic species cover which is currently low in most Newnes Plateau shrub swamps (Benson and Baird 2012). Our results show that the ability to detect change over time could be improved by permanently marking the locations of transect start and end points and possibly also some individual quadrats at sampling sites, particularly those with very uneven topography and tall, dense vegetation.…”

“…changes in water availability and disturbance) as monitoring variables, rather than species, can help to overcome these issues (Casanova 2011;Campbell et al 2014;Johns et al 2015). We also considered this approach appropriate for the monitoring program discussed here because earlier work had identified substantial heterogeneity in species composition and relative abundance, both within and between Newnes Plateau shrub swamps (Benson and Baird 2012;Brownstein et al 2015;Johns et al 2015;Tierney et al 2015).…”

Ecotones as indicators: boundary properties in wetland-woodland transition zones

“…The Newnes Plateau is a floristically important area because it contains several endangered plant species and communities, including the Newnes Plateau Shrub Swamps which are protected as Endangered Ecological Communities under New South Wales legislation (DEC 2006). Newnes Plateau Shrub Swamps are located on periodically to permanently waterlogged alluvial soils along open drainage lines; and are characterized by a dense to sparse shrub canopy and sedge understory with occasional emergent eucalypt trees (Benson and Baird 2012). The surrounding vegetation is characterised by tall eucalypt forests and woodlands with a diverse moderately dense shrub and herb layer (DEC 2006) and boundaries between communities evident as a sharp (2m to 3m wide) vegetation transition seemingly related to moisture availability (Benson and Baird 2012).…”

“…Newnes Plateau Shrub Swamps are located on periodically to permanently waterlogged alluvial soils along open drainage lines; and are characterized by a dense to sparse shrub canopy and sedge understory with occasional emergent eucalypt trees (Benson and Baird 2012). The surrounding vegetation is characterised by tall eucalypt forests and woodlands with a diverse moderately dense shrub and herb layer (DEC 2006) and boundaries between communities evident as a sharp (2m to 3m wide) vegetation transition seemingly related to moisture availability (Benson and Baird 2012). The potential anthropogenic impacts on the hydrology of these communities include lowering of water tables (related to underground mining) or increased volume of intermittent surface flows of water pumped from underground mines.…”