David Bishop, NZ Forest Service, Westland Conservancy

Westland is situated on the West Coast of the South Island of NZ. It extends from Karamea in the north to Haast in the South. The major area of karst is located about Charleston. The karst is in a narrow band, some 30km in length by 3-5km wide, and comprises 12,000 hectares (approx).

There is a diversity in landforms, with karst about the coastline; mudstone in the central region and granite on the main Paparoa Range.

The forests and landforms are zoned for primary uses:

  1. ecological - representative examples of forest types and landforms reserved for scientific purposes.
  2. amenity - areas with scenic or historic values.
  3. protection - forest and landforms where the main requirement is soil and water conservation for reasons of slope, altitude or stability.
  4. indigenous - areas where the forests are managed for a perpetual yield of wood.

Much of the karst region about Charleston (80%) is protected in various reserves (a), (b) or (c).

Harvesting of a small part of the karst region was carried out in the 1960s. It was richly forested with indigenous softwoods (kahikatea and rimu), and hardwoods (kamahi and beech species). Operations used high lead winch systems; however, it was difficult country to work, with log shatter a common experience. Harvested areas regenerated strongly again in beech and softwood species.

Our interest in caves began with discoveries centred about the Metro Cave system. Following recommendations from Prof. P. Williams (Auckland University), protective measures were undertake when part of the upper catchment of the cave was to be harvested. These measures included winch sites and roading being set back out of the catchment area; riparian reserves about the stream etc. Also, hydrological studies were initiated. These include measuring flood levels with crest stage gauges, and water sampling during flooding to monitor sedimentation levels. These studies continue (harvesting finished in 1981), in order to provide long term data.

Good management of karst requires information on the resources and inputs that make up the karst. Both geological mapping and forest type mapping data was available. However, the descriptions and locations of known caves in the region was not compiled or available in an index.

Hence the Forest Service found it necessary to carry out an inventory of known karst features (caves, tomos etc) in the region. This involved researching NZ Speleological Society bulletins and collating unpublished reports etc. To date 120 caves and features are recorded.

The task of the Forest Service is to manage crown land for a variety of uses. With the adoption of the new cave and karst policy, and the availability of cave information from the new karst index, the task for good management will be made easier.