Journal of the Royal Society of Western Australia, 86(1), March 2003 
entirely dependent on groundwater. A species' ability to 
access groundwater during a summer drought may 
ultimately influence it's distribution within the landscape 
(Zencich et al. 2002). 
Materials and Methods 
Study site 
The Lexia wetlands are a chain of wetlands on the 
eastern edge of the Gnangara Groundwater Mound, a 
large, shallow unconfined aquifer on the coastal 
sandplain north-east of Perth, Western Australia. The 
Lexia wetlands are unique when compared to othe*. 
wetlands on Perth's coastal sandplain as they hav^ 
remained undisturbed from human impact. The majority 
of the Lexia wetlands are damplands (seasonally 
waterlogged basins; Semeniuk 1987), which may hav^ 
surface water depending on the amount of winter rainfall 
received and regional groundwater levels. A study or\ 
the hydrology and stratigraphy of these wetland^ 
indicated that many of the Lexia wetlands may b^ 
perched at a soil depth of 2-3 m (Semeniuk & Semeniul^ 
1993). 
The vegetation surrounding these damplands ty 
dominated by an evergreen Banksia (Proteaceae) 
Figure 1. A: Location of study sites and two permanent groundwater monitoring bores (triangles) within the Lexia chain of wetlands 
(shaded areas), 25 km NE of Perth, Western Australia. B: Distribution of target species and position of sites (thick black lines represent 
groundwater monitoring piezometers) in the study area. Groundwater profile represents a typical spring (October) water table. Species 
abbreviations: Af = Astartea fascicularis; Pe = Pericalymma ellipticum ; Ha = Hypocalymma angustifolium; Ep = Eremaea pauciflora. 
32 
