Tasman’s land cover profile is characterised by:
- A predominance of forest cover, of which most is indigenous forest falling within the conservation estate administered by the Department of Conservation. This includes the Kahurangi, Nelson Lakes, and Abel Tasman national parks and numerous scenic and conservation reserves. Forest cover in Tasman is around 652,500 hectares, approximately 67% of the region.
- A substantial area of grassland/other herbaceous vegetation (about 19% of land area), of which 13% is exotic grassland, but with some tussock grassland also (5%). Pastoral area is found throughout the region on the valleys, plains, and on the gentler Moutere Gravel hill country.
- Scrub/shrubland covers 8% of the region. This is predominantly comprised of indigenous scrub/shrubland, in particular Manuka and/or Kanuka.
- Cropland comprises a relatively small proportion of the regional land area overall (9,409 ha; 1% and is mainly situated on the Waimea and Motueka Plains. Small areas of pipfruit and viticulture are still found on the coastal areas of the Moutere Gravels.
The key changes in land cover between 1996 and 2018 in the Tasman region are:
- Grassland/other herbaceous vegetation has decreased in area by about 2,700 ha (or 1%). This is primarily from exotic grassland, which has decreased by around 2%. Scrub/shrubland (comprising both exotic and indigenous scrub/shrubland) has also decreased in area, by 5% (decreases of 14% and 4% respectively).
- Exotic forest, urban area, and cropland have increased in area by 5%, 41% and 4%, respectively.
The likely drivers and potential implications of the changes are:
- The increase in exotic forest area may have been driven by growing confidence in the forestry industry and the introduction of the emission trading scheme. 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 increase in urban area is likely to have been driven by population growth and increased demand for housing. 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 productive and versatile land from productive uses (e.g. commercial vegetable production).
- The increase in the area of cropland may be largely driven by growth in horticultural industries such as viticulture (most of the change in area was in ‘orchards, vineyards or other perennial crops’ rather than ‘short-rotation cropland’). 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 decrease in the areas of indigenous scrub/shrubland could have implications for the conservation of indigenous biodiversity.
