Change in wetland extent and distribution indicates where natural areas have been lost (for example through drainage), or gained (for example through wetland creation on retired pasture).
Wetlands are an important storehouse of native biodiversity. Native plants and animals, and the wetland ecosystems they form, are valued for their unique genetic diversity, cultural and spiritual importance, scientific interest, recreational opportunities and intrinsic values. In addition wetlands provide many environmental services, improving water quality, storing carbon, and reducing the effects of floods.
Change in extent of remaining wetlands may affect the diversity and security of native species. By monitoring changes in wetland extent Environment Waikato gains information on where land use pressures are occurring. This information help us identify policy responses to avoid or reverse adverse effects on wetland biodiversity.
This indicator describes and quantifies the spatial extent, distribution of, and temporal changes in, freshwater wetland vegetation. Waikato Regional Council uses the Land Cover Database (LCDB) to monitor current freshwater wetland vegetation. The historic extent of freshwater wetland vegetation (at about 1840) is estimated from the Regional Indigenous Vegetation Inventory (RIVI) (1840).
Before European settlement (around 1840), native vegetation covered most of the Waikato Region. It’s estimated that about 108,000 hectares was wetland (five percent of the Region). The largest areas were peat bogs next to the Waikato River, north of Cambridge and in the Hauraki Plains. Today, only a quarter of those 1840 wetlands are left (one percent of the Region).
The Waikato Region remains a stronghold for wetlands in New Zealand. They are mostly in the lower Waikato Valley and Hauraki Plains. The largest remaining areas, Kopouatai Peat Dome and Whangamarino Wetland, are internationally significant.
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Leathwick, J.; Clarkson, B. and Whaley, P. 1995: Vegetation of the Waikato Region: Current and Historic Perspectives. Landcare Research Contract Report LC9596/022. Landcare Research, Hamilton.
Denyer, K.; Clarkson, B.R and Clarkson, B.D.1999: Waikato Freshwater Wetland Monitoring Strategy: Scoping Exercise For State Of The Environment Monitoring. Landcare Research Contract Report LC9596/022. Landcare Research, Hamilton. (DOCs 662475).
Because of the time scale at which vegetation change (other than clearance/drainage) occurs, it is unlikely that changes will be monitored any more frequently than five yearly.
The Ministry for the Environment intends to update the LCDB every five years. Therefore, the updating of this indicator is also dependent on production of the updated LCDB and Environment Waikato’s continued purchase of this data.
Terrestrial Ecologist - Science and Strategy Directorate