Prof. Alan Mark (Department of Botany)

Mr. Bruce McLennan (Department of Information Science)

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About this study
The conservation status of New Zealand's indigenous grasslands has been assessed, as of September 2002, against an 1840 baseline, i.e., immediately before European settlement. This was when the grasslands were at their maximum extent and also still essentially indigenous.

This study was intially requested by Bill Henwood, of Parks Canada, as part of a global assessement of the conservation status of temperate indigenous grasslands undertaken by the World Conservation Union (IUCN). The results were presented at the Vth World Parks Congress held in Durban, South Africa in September 2003.

Five major grassland types are recognised, four of them tussock grasslands: low-alpine and montane to subalpine snow tussock grasslands, montane to subalpine tall red/copper tussock grassland, montane to subalpine short tussock grassland, and lowland sward grassland. The assumed extent in 1840, of areas with at least some grassland dominance, was mapped at 1:50,000 or larger, on the basis of the best available information, by Geoff Rogers (North Island), Shannel Courtney (Nelson-Marlborough), Peter Wardle (Canterbury and Central-North Westland, Alan Mark (Otago-South Westland) and Brian Rance (Southland). The current (Sept. 2002) extent was also mapped, on the basis of the 'tussock' category in the Land Cover Data Base 1 map (typed as for the baseline map) plus all areas formally protected at this time (records from Department of Conservation). Ecological region boundaries were added and the map information scanned and compiled using ArcGIS™. North Island areas were also assessed as one unit while South Island areas were grouped into one of three broad geographic regions, based on general land use patterns: the rain-shadow rangeland, the western wet non- rangeland, and the eastern lower altitude non-rangeland regions.

The total baseline extent of indigenous grasslands was estimated at 84,536 km² (c. 31% of the land area), with another 8701 km² (c. 3.2%) being various high-alpine communities and 1254 km² (c. 0.5%) being permanent ice and snow. Of the grasslands, c. 13% was low-alpine snow tussock grassland (above the climatic treeline), c. 18% montane to subalpine snow tussock grassland, c. 22% montane to subalpine red/copper tussock grassland, c. 44% montane to subalpine short tussock grassland, and c. 2% lowland sward grassland. Most grassland (57%) was in the South Island rangeland region, with 24% in the eastern South Island non-rangeland, 10% in the North Island and 8% in the western non-rangeland regions.

The areas remaining of each grassland type vary largely in relation to altitude and climate, with the greatest reduction from the baseline areas being in the drier lower-elevation regions. Only scattered remnants of the sward grasslands persist. Overall, protection of the remaining indigenous grasslands, with various degrees of modification and/or degradation, amounts to some 12% of the baseline extent, with a strong bias towards those at the higher altitudes. Geographically, it is greatest in the South Island wet western region (89% of the 98% which still remained as of September 2002), w8th less in the North Island (40% of the 17% which remains) and eastern South Island non-rangeland region (11% of the 3% which remains). Grassland protection in the South Island rangeland region (12% of the 76% which remained as of September 2002) is currently increasing through tenure review of the Crown-owned pastoral leasehold land here.

Maps
1840 Nth Island low res (200kb) high res (2.5Mb)			2002 Nth Island low res (200kb) high res (2.5Mb)		New Zealand ecological regions low res (100kb) high res (2Mb)
1840 Sth Island low res (200kb) high res (2.5Mb)			2002 Sth Island low res (200kb) high res (3Mb)

Tabulated Results
Click here to view tables of the extents of each grassland type in 1840 with the percentages remaining in 2002 and under formal protection by geographic region (table 1) and by ecological region (table 2).

Downloadable data sets
The data sets that were developed for this study are available for down-loading as ArcGIS shape files. The shape files include data representing the extents of indigenous grasslands, for both 1840 and 2002, on an ecological region basis, as well as for high-alpine and nival areas for the same periods and regions.

Comments and/or suggested refinements would be welcomed and should be directed to Prof. Alan Mark.