Table 1. Sub-indices, components and measures used in the IWC (DSE 2005). Key ecological Measure Measure IWC sub-index component type Percentage of land in different land use intensity Wetland catchment Threat classes adjacent to the wetland Wetland catchment Average width of the buffer Component Wetland buffer Percentage of wetland perimeter with a buffer Component Area of the wetland Percentage reduction in wetland area Component Percentage of wetland where activities Physical form Wetland form (excavation and landforming) have resulted in a Threat change in bathymetry Severity of change to the water regime expected Hydrology Water regime from activities identified to alter the water Threat regime Macronutrients (such as Severity of nutrient enrichment Threat nitrogen and phosphorus) Water Severity of change in salinity properties Electrical conductivity Threat (salinity) Soil physical properties Percentage and severity of wetland soil Soils (soil structure, texture, disturbance Impact consistency and profile) Wetland vegetation quality assessment based on: critical lifeforms Component Biota Wetland plants presence of weeds Impact indicators of altered processes Impact vegetation structure and health Component Wetland catchment Land use change and native vegetation clearing within the wetland catchment can cause changes in the amount and timing of water supply (surface water flows and groundwater levels) and the levels of nutrients, sediments and pollutants entering the wetland, and can cause secondary salinisation and a reduction in habitat quality for wetland fauna. Native vegetation adjacent to the wetland (i.e. within the buffer) plays an important role in ameliorating these impacts. It also provides protection from disturbance for wetland fauna. Physical Form The physical form of a wetland influences flooding depth, inundation duration and mixing. It also influences biological processes. The area of the wetland determines the amount and proportion of available habitat for biota. The bathymetry (underwater topography) of a wetland is determines the types of habitats present in a wetland. The principal threats to physical form are permanent reductions in wetland area (conversion to dry land by draining, filling, reduced water input etc.) and modifications to the wetland bed (by
Table 1. Sub-indices, components and measures used in the IWC (DSE 2005). IWC sub-index Key ecological component Measure Measure type Wetland catchment Wetland catchment Percentage of land in different land use intensity classes adjacent to the wetland Threat Wetland buffer Average width of the buffer Component Percentage of wetland perimeter with a buffer Component Physical form Area of the wetland Percentage reduction in wetland area Component Wetland form Percentage of wetland where activities (excavation and landforming) have resulted in a change in bathymetry Threat Hydrology Water regime Severity of change to the water regime expected from activities identified to alter the water regime Threat Water properties Macronutrients (such as nitrogen and phosphorus) Severity of nutrient enrichment Threat Electrical conductivity (salinity) Severity of change in salinity Threat Soils Soil physical properties (soil structure, texture, consistency and profile) Percentage and severity of wetland soil disturbance Impact Biota Wetland plants Wetland vegetation quality assessment based on: critical lifeforms presence of weeds indicators of altered processes vegetation structure and health Component Impact Impact Component Wetland catchment Land use change and native vegetation clearing within the wetland catchment can cause changes in the amount and timing of water supply (surface water flows and groundwater levels) and the levels of nutrients, sediments and pollutants entering the wetland, and can cause secondary salinisation and a reduction in habitat quality for wetland fauna. Native vegetation adjacent to the wetland (i.e. within the buffer) plays an important role in ameliorating these impacts. It also provides protection from disturbance for wetland fauna. Physical Form The physical form of a wetland influences flooding depth, inundation duration and mixing. It also influences biological processes. The area of the wetland determines the amount and proportion of available habitat for biota. The bathymetry (underwater topography) of a wetland is determines the types of habitats present in a wetland. The principal threats to physical form are permanent reductions in wetland area (conversion to dry land by draining, filling, reduced water input etc.) and modifications to the wetland bed (by
Wetland-Tender-Field-Officer-Manual.docx