Northland’s land cover profile is characterised by:
- A predominance of grassland/other herbaceous vegetation cover (almost half of the land area), of which most is exotic grassland.
- A substantial area of forest cover (more than one third of the land area), of which most is indigenous forest, but there is a significant area of exotic forest also.
- Scrub/shrubland cover is predominantly comprised of indigenous scrub/shrubland.
- Urban area, cropping/horticulture, other herbaceous vegetation, exotic scrub/shrubland, and natural bare/lightly-vegetated surfaces comprise relatively small proportions of the regional land area overall (1% each).
The key changes in land cover between 1996 and 2018 in the Northland region are:
- Exotic grassland, indigenous forest, and indigenous scrub/shrubland have decreased in area.
- Exotic forest, urban area, and cropping/horticulture have increased in area.
The likely drivers and potential implications of the changes are:
- The increase in urban area is likely to have been driven by population growth and increased demand for housing, particularly in parts of Whangarei, Kerikeri, and Mangawhai. The expansion of urban areas onto surrounding rural land will reduce the land area available for primary production and, in some areas, could result in the loss of highly versatile land from productive uses (e.g. horticulture or commercial vegetable production).
- The increase in the area of cropland may be largely driven by growth in cropping industries/management systems (most of the change in area was in ‘short-rotation cropland’ rather than ‘orchards, vineyards or other perennial crops’). Soil cultivation, more commonly associated with short-rotation cropping, can result in increased losses of soil carbon, sediment, and nutrients, and soil structural degradation over time.
- The increase in exotic forest area may have been driven by increased confidence in the forestry industry and the introduction of the ETS. The afforestation of hillslopes at risk of erosion (e.g. steep or with fragile soils, or both) under grassland cover can be beneficial in terms of improving slope stability and reducing the incidence of soil erosion.
- The decrease in the areas of indigenous forest and indigenous scrub/shrubland could have implications for the conservation of indigenous biodiversity.
