Environmental Distinctiveness

The identification of distinctive areas of ecosystem character (rare environmental combinations) is essential for the management and protection of the entire range of biodiversity. Areas of high environmental distinctiveness are used as indicators of areas of ecosystem distinctiveness. Purpose: To recognise areas that are distinctive in ecosystem character.

A surface of distinctiveness relative to the entire nation identifies areas with environmental combinations that are rare in NZ. A surface of distinctiveness relative to the reserve network identifies areas that are most different from protected areas.

New Zealand wide

Waikato Region –

historic climate data, landform variable from the NZ LRI (1974).

Environmental distinctiveness provides a continuous measure of ecosystem dissimilarity. Calculations of distinctiveness are made for every pixel of a digital elevation model (DEM), relative to a reference set. For each pixel, the distance of that pixel to another pixel in the reference set is calculated along each environmental axis. The mean of the distances along each of the axes then provides a measure of the environmental distance between the pair of pixels. The mean environmental distances are then averaged across all pixels in the reference set to provide the environmental distinctiveness of the target pixel. This process is repeated for every pixel of the nation (or region of interest). Environmental distances are measured using the Gower metric, which is based on a range-standardised manhattan distance. Environmental variables used in the calculations of distinctiveness are: mean annual temperature, minimum winder temperature, mean annual solar radiation, winter minimum solar radiation, minimum ratio of rainfall to potential evapotranspiration, October (spring) air saturation deficit, and annual soil water deficit, slope, drainage, and soil parent material. The reserve network was defined as the areas of public land managed for conservation by DoC. It excludes other types of conservation reserves such as covenants. Frequency of collection: Various

Each pixel is considered protected if the centre of the pixel falls within a protected area, and no attempt has been made to assess the proportion of the 1 km2 pixel that is protected. While this is an approximation, it is an unbiased approximation, and works well at national scales. Further analyses with smaller pixels are being prepared. Gaps in collection: None Data quality: Not reported Attribute accuracy: Not reported Completeness: Environmental variables used in the calculations of distinctiveness are the same as those used for environmental classifications using the environmental domains approach (Leathwick et al. 1998).

report, spreadsheet Digital Format: GIS Raster data, ArcView 3.2 (S-plus)

Biodiversity management

Freely available. Small cost to map for regional or local scale. Sensitivity/Confidentiality: None

Pilot demonstration at national scale. Smaller scale mapping available.