PARENT SESSION
Poster Session 4: Marine Ecology
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Impact assessment of shack settlement to coastal vegetation at Wedge Reserve, central coast Western Australia.

O'Dwyer, Steve^{*,1, 2}, ¹ Edith Cowan University, Perth, WA, Australia² Ecological Society of Australia, Canberra, ACT, Australia

ABSTRACT- Gradient analysis was used to assess disturbance to coastal vegetation at Wedge, central Western Australia. Wedge has supported a shack settlement for 50+ years and is subject to increasing pressures from greater visitor, tourist and recreational numbers. Data from 96 quadrats within Wedge Reserve 43283 were collected from the dunes for vascular flora and environmental characteristics. Square root transformed percentage species cover and 19 environmental variables were used for indirect and direct gradient analyses (NMDS, CCA). Distance from the coast, landform and number of native species delineated the natural succession of vegetation patterns from coast to inland. This succession was classified as five individual landform units (foredune, primary dune, swale, secondary dune, flat and tertiary dune) within two broad landform types (1 & 2) and sampling sites were assigned a control (outside settlement) or impact (within shack settlement) status and landform type for analysis. CCA and NMDS then separated out variation in disturbed areas and identified that, although plant diversity was reduced for impact sites and contrary to expectations, there was an increase in vegetation percentage cover (30%) than for control sites. The reverse held true for percentage bare ground. Two native species, Acacia cyclops and Myoporum insulare and a non-native grass, Bromus diandrus had significant percent cover increases for impact sites. A range of native species had greatly reduced percentage covers for impact sites than control sites. Gradient analysis highlighted a number of latent variables that contributed to vegetation patterns, including conductivity at 50cm depth which correlated with impact sites.

Key words: disturbance, coastal vegetation, gradient analysis, terrestrial