Changes in vegetation patterns on the margins of a constructed wetland after 10 years

Authors

  • Leigh M. Garde,

  • Jason M. Nicol,

  • John G. Conran


  • This paper is based on research undertaken by Leigh M. Garde (3/35 Ashby Ct, Kambah, ACT 2902, Australia, formerly of the Mawson Graduate Centre for Environmental Studies) and Jason M. Nicol and John G. Conran from the Discipline of Environmental Biology, School of Earth and Environmental Sciences, Darling Building, DP418, The University of Adelaide (SA 5005, Australia. Tel: +61 8-8303 5684, Email: john.conran@adelaide.edu.au). The project was undertaken in part towards a M. Env. Studies degree by Ms Garde and continued as part of ongoing research in community ecology and wetlands through the Centre for Evolutionary Biology and Biodiversity and the CRC for Freshwater Ecology within the School of Earth and Environmental Sciences.

Abstract

Summary  A constructed urban wetland in Adelaide was surveyed 18 months and 10 years after construction to see how shoreline vegetation, soil electrical conductivity (EC), texture and pH changed over time and to provide data for future site management. Multivariate analysis detected four plant associations at 18 months: salt-tolerant taxa on conductive clays; a weed-dominated community on lower EC soil; and two smaller waterlogged, low EC clusters dominated by Common Reed (Phragmites australis) and Sea Club-Rush (Bolboschoenus caldwellii), respectively. At 10 years, site cover and heterogeneity was higher, with the margins dominated by Phragmites and salt-tolerant species. EC was much lower and more uniform, and the soils were heavier and more alkaline. Managed storm water flushing apparently lowered soil EC, but possibly also disturbed the shoreline. However, weeds were still common, and the potential for domination by Phragmites at the expense of other native shoreline species means that ongoing monitoring and hydrological and vegetation management are essential to maintain site habitat diversity.

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