New Zealand Wetland Condition Index (WCI)

The New Zealand Wetland Condition Index (WCI) was developed for State of the Environment monitoring and reporting in all freshwater wetlands in New Zealand. It is a semi-quantitative metric comprising five ecological indicators based on the major threats and stressors known to degrade wetlands.

The New Zealand National Wetland Monitoring System (NWMS) approach determines overall ecological condition of a wetland by comparing against an assumed natural state, such as pre-settlement, to measure a Wetland Condition Index (WCI). The WCI is informed by the relevant monitoring methods in  the 'Handbook for Monitoring Wetland Condition'[1]. The approach has been updated (2017) to address additional reporting requirements for State of the Environment monitoring[2].

The WCI indicators are scored at both a broad wetland-wide scale and a more detailed plot scale to account for differences in scale and monitoring requirements, and to underpin scores with quantitative scientific data. The plot-based approach is the foundation for the Protected Natural Areas Programme in New Zealand. This approach initiates a process in which detailed field reconnaissance, ground-truthing, establishment of representative plots, and collection of data, together with integrating existing information, are necessary steps to facilitate informed assessment and scoring of indicators[2].

Condition is scored using five indicators to reflect the extent and impact of modification (disturbance), where a high degree of modification provides a low score. The indicators relate to the major threats known to damage wetlands. The sum of the indicator scores provides a WCI. Indicator component scores are averaged to produce a score out of 5 for the indicator, and summed to provide an overall WCI score out of a maximum of 25. The higher the score, the better the ecological condition[1].

It is derived from a process involving wetland classification, mapping and delineation of vegetation types, field reconnaissance, ground-truthing, establishing representative plots, and collection of data to facilitate informed assessment of the indicators[2].

The WCI can be used to compare changes at different levels and scales, e.g., within an individual wetland, or across a wetland type in a watershed, region, or nation-wide, to gauge the effectiveness of policies, rules and other legislation. This system is the basis for the development of community-based and additional monitoring systems (e.g. WetMAK https://www.landcare.org.nz/resource-item/wetmak).

The indicators and component indicators are:

• change in hydrological integrity: impact of man-made structures; water table depth; dryland plant invasion
• change in physicochemical parameters: fire damage; degree of sedimentation/ erosion; nutrient levels; von Post Index
• change in ecosystem intactness: loss in area of original wetland; connectivity barriers
• change in browsing, predation and harvesting regimes: damage by domestic or feral animals; introduced predator impacts on wildlife; harvesting levels
• change in dominance of native plants: introduced plant canopy cover; introduced plant understorey cover[1].

Desktop data to inform the survey includes:

• wetland classification
• wetland mapping
• delineation of vegetation.

Plot field data includes:

• water quality, water table and von Post analyses
• soil analyses
• foliage analyses
• vegetation cover and composition data.

Indicator data includes a range of project- and module-based indicators and measurables.

Depending on the type of assessment carried out, the main skills needed generally include:

• basic data analysis
• good data management (making sure information is recorded and data not lost)
• specialist identification (flora, fauna) skills
• ideally computer skills (e.g. Word and Excel).

• 'Handbook for Monitoring Wetland Condition'[1].
• Wetland record sheet, plot sheets and aerial photos of wetland at suitable scale.
• Poles to mark permanent plots, GPS if available and/or topographic map and tape measures.
• Sediment sampling equipment including steel liner for taking substrate/soil cores, knife, plastic bags, permanent markers.
• Foliage sampling equipment (paper bags or envelopes).
• Field pH and conductivity meter (if available).
• Von Post scoring scale.

Each of the indicators is measurable, and the sum of the indicator scores providing the WCI. Outputs include analysis and evaluation of both the total WCI, the scores of the individual indicators and components, and a brief monitoring report.

The WCI can be used for State of the Environment wetland monitoring requirements, to inform council policy, plans and management priorities etc., gauge the effectiveness of these mechanisms, and form the basis for community-based monitoring systems.

For State Government, the State of the Environment monitoring and reporting on New Zealand terrestrial wetlands.

• Indicators supported by technical plot quantitative data.
• Assesses threats and condition indicators separately.
• Modular, flexible and adaptable to a range of projects.
• Does not require elaborate databases or software.

• Mostly semi-quantitative criteria, which requires experienced and trained ecologists.
• Full monitoring includes expensive laboratory analyses and field equipment.

Lake Maratoto Peatland wetland condition

Moanatuatua Peat Scientific Reserve Restoration Plan

New Zealand wetland condition monitoring

Restoring wetland ecosystem function

‘Using the WCI: Ecological change at the Cockayne Reserve’ within Chapter 13: Monitoring

This page should be cited as:

Department of Environment, Science and Innovation, Queensland (2021) New Zealand Wetland Condition Index (WCI), WetlandInfo website, accessed 18 March 2024. Available at: https://wetlandinfo.des.qld.gov.au/wetlands/resources/tools/assessment-search-tool/new-zealand-wetland-condition-index-wci/