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Wetland soils

Soils are potentially powerful indicators of the presence of wetlands because of the morphological features that develop in wet environments.

Wetland soils impact directly on other wetland characteristics, e.g. water quality, fauna or vegetation, and can be a reflection of the physical processes occurring in the wetland, e.g. water inflow, water chemistry or filtering of pollutants.

There is a variety of soils across Queensland. They are broadly grouped into soil orders based on the Australian Soil Classification system (ASC).

Soils at Eurimbula Photo by Queensland Government

Quick facts

The length
of time wetland soils are saturated or flooded determines the anaerobic conditions in the upper layers of the soil profile. These anaerobic and/or saturated conditions will influence the development of the wetland soil as well as the wetland plant species that will grow.

Soil Indicators of Queensland Wetlands

Soil Indicators of Queensland Wetlands uses soil properties to help identify wetlands and wetland boundaries. The five products in the suite support planners, environmental managers and wetland rehabilitation managers to establish the precise location of wetlands. The tools include a literature review, field guide, assessment methodology, 39 case studies and the Indicator of Reduction in Soils (IRIS) method.

Four conditions are required for a soil to become anaerobic and support reducing reactions and the development of soil morphological features. If these chemical transformations occur in the soil’s upper layers:

  • The soil must be saturated to the point of excluding atmospheric oxygen.
  • The soil must contain a source of organic matter that can be oxidised or decomposed.
  • The soil must contain a population of respiring microbes that will oxidise the organic matter.
  • The water must be stagnant or slow moving.

Wetland soils can be identified using soil morphological indicators such as:

  • the accumulation of organic matter
  • gleyed soil colours
  • soil mottling
  • iron or manganese segregations
  • oxidising root channels and soil pore linings
  • reduction of sulphur and carbon (e.g. acid sulfate soils).
Wetland soil derived from sands. The dark, fibrous surface layer shows clear accumulation of organic matter. Photo by DES
Oxidised root channel linings in a soil ped. This morphological feature was observed throughout the top 30cm of a wetland soil. Photo by DES
Aerial roots on a Melalueca spp, suggesting that the surface soil in this wetland remains under anaerobic conditions for many months at a time. Photo by DES

Wetland soils impact directly on other wetland characteristics, e.g. water quality, fauna, vegetation, and can be a reflection of the physical processes occurring in the wetland, e.g. water inflow, water chemistry, filtering of pollutants.

Wetland soils assessment reports and supporting information

The following reports provide information and background to support the identification of wetland soils.

Soil indicators of Queensland wetlands: Statewide assessment and methodology

The report details and discusses findings of a statewide assessment of wetland soil indicators conducted by the Department of Natural Resources and Water during 2007 and 2008 under the Queensland Wetlands Program.

Soil Indicators of Queensland Wetlands: Field Guide

The field guide has been developed to assist in the field identification of wetland soil indicators in Queensland.

Soil Indicators of Queensland Wetlands Phase 1: Literature Review and Case Studies

The report highlights two case studies of wetlands within Southern and Central Queensland to test if predictable relationships exist between soil indicators identified within the literature and wetland status for Queensland wetland soils.

Indicators of Reduction in Soils

The report outlines the Indicator of Reduction in Soils (IRIS) method for identifying wetlands and demonstrates how to use the method on wetlands in Queensland. Field indicators of ephemeral wetlands can be hard to find in dry times. Wetland soils—identified by reducing conditions—become a major indicator of existence and extent.

Wetland soil case studies

The proposed wetland soil indicators were tested in 58 wetlands, representing a range of wetland classes, climatic zones and biogeographical regions. Thirty-nine case studies have been developed.

Additional information


Last updated: 18 November 2015

This page should be cited as:

Wetland soils, WetlandInfo 2013, Department of Environment and Science, Queensland, viewed 14 December 2018, <https://wetlandinfo.des.qld.gov.au/wetlands/ecology/components/soils/>.

Queensland Government
WetlandInfo   —   Department of Environment and Science