This indicator describes and quantifies the change in extent and distribution of indigenous terrestrial vegetation. The Waikato Regional Council uses the Land Cover Database1 (LCDB) to monitor current indigenous vegetation. The extent of indigenous vegetation in 1840 is estimated from the Regional Indigenous Vegetation Inventory (RIVI 1840)2.
Land cover types from the LCDB are used to estimate indigenous vegetation classes. All ‘indigenous’ and ‘predominantly indigenous’ land cover types have been divided into classes incorporating indigenous forest, scrub and shrubland3, tussock grassland, inland wetland, mangrove, and coastal dune vegetation. This indicator is restricted to terrestrial indigenous forest, scrub and shrubland and tussock grassland.
Indigenous vegetation extent and distribution change indicates where natural areas have:
Areas of indigenous vegetation are an important storehouse of indigenous biodiversity. New Zealand is known internationally for its unusual plants and animals, many of which are found nowhere else in the world. Loss of habitat, along with the introduction of animal and plant pests, has had a major role in extinctions and the high number of threatened species in New Zealand.
Some ecosystem types, for example lowland forest and coastal forest, scrub and shrubland, have become very rare because the land they grew on is highly valuable for other uses such as farming or urban settlement.
Change in extent of native vegetation means potential change in the diversity and security of native species. Waikato Regional Council monitors changes in vegetation extent to provide information on where land use pressures are occurring, which vegetation and habitat types are at greatest risk of loss and for reporting on biodiversity. This helps us identify policy responses to avoid or reverse adverse affects on our biodiversity.
Before European settlement (around 18401) the only land in the Waikato region not covered by indigenous (native) vegetation was areas of bare rock or permanent snow and ice. Forest covered 52 per cent of the region, but scrub and shrubland and tussock grassland grew where fires were frequent, or the land too wet or cool for forest.
Change in land use, for example to agriculture, plantation forestry and urban settlement, has required clearing indigenous vegetation. Today, 27 per cent of the region’s land area is in indigenous vegetation cover2. The remaining extent of indigenous forest, scrub and shrubland3and tussock grassland combined is around 649,458 ha. Other natural areas in the region include wetlands and coastal habitats which are reported in separate indicator report cards.
The greatest loss of indigenous terrestrial (land-based) vegetation since 1840 occurred in the central Waikato lowlands, around Hamilton City and in the Waipa, Waikato, South Waikato and Matamata-Piako districts where fertile soils on gentler topography were suitable for livestock farming, or where the hills were cleared for pine plantations. Districts with more rugged hill country and extensive ranges, such as Taupo, Otorohanga, Waitomo and Thames-Coromandel have a greater proportion of indigenous forest, scrub and shrubland and tussock remaining.
Coastal, lowland and sub-montane bioclimatic zones (below 800 metres elevation) lost the greatest portion of their indigenous cover, with over 60% of each of these zones cleared for another land use.
The updating of this indicator is dependent on production of the updated LCDB. Because of the time scale at which vegetation change (other than clearance/drainage) occurs, it is unlikely that change will be monitored any more frequently than five yearly.
Terrestrial Ecologist - Science and Strategy Directorate.
For information on data quality (lineage, positional accuracy, attribute accuracy, logical consistency and completeness) see the updated metadata for the LCDB available on the Landcover Database website - Land Cover Database (metadata).
For detail on the methods used to reconstruct 1840 vegetation in the Waikato region see Leathwick et al., 1995.