West Coast also has exotics to market

Press, 7 October 1980, Page 22

West Coast also has exotics to market

Exotic forestry on the West Coast has something of a Cinderella quality. Lt’s a bit of a Little Orphan Annie, too — no-one seems to be quite sure what it’s doing there, -or where a market will be found for the trees when they mature. That fateful time tends to arrive fairly rapidly on the West- Coast, because if there is one thing that province does well, it- is growing trees. Evidence of ■this can be. found in eucalyptus plantations on the better State forest blocks in North Westland. At the age of eight years they have already made a forest, with a closed canopy and trunks thicker than a man’s leg; some of them are 15 metres or more high.Australian eucalyptus trees were introduced to the West Coast experimentally to plug the gaps left in the bush by “selective logging” for podocarps (rimu and kahikatea), and to act as a nurse crop for young beech seedlings. While they were not very successful for the former purpose (they proved to be superb hosts for the damaging platypus beetle), they showed themselves, when planted on their own, to be capable of spectacular growth, at least for their first 10 years. But in the longer term it will be the pines and Douglas firs that support exotic forestry in Westland, as they do everywhere else in the country, even if they have to go begging for a market.

Only the conifers will succeed in the area where exotic forestry is no Orphan Annie — the restoration to productivity of the pakihi swamplands. Pakihi is a phenomenon unique to the West Coast:

swampy areas of ill-> drained, peaty soil of very high acidity, usually on plateaux or in basins among hills. The soil is so sour and wet that few plants will grow in it. Many pakihi areas are man-made; once, before the logging gangs moved in, they were covered with podocarp forest.

The establishment of exotic trees in these areas, with the aid of fertilisers and bulldozer-inspired drainage, is one of the success stories of forestry in New Zealand, even if a question mark does hang over the future ability of the trees to stand fast in gales on the jelly-like soil. Drainage is the key to pakihi afforestation, as indeed it is to all forestry on the West Coast. In much of the area set aside for production forestry in North Westland, the soil is poorly drained and poverty-stricken, a reflection of glaciations, in ages past. And this combination of gooey clay and a high rainfall —5000 mm a year in places — ensures that any nutrient added to the soil remains there only a short time.

The eucalyptus trees do best where the drainage is good, and the three species that have been tried have all given remarkable early results in suitable areas. All — Eu- >

calyptus nitens, E. regnans, and E. delegatensis — produce timber of high quality in Australia, and one of the reasons for their presence in Westland is to provide, even if on a very minor scale, a substitute for the podocarps when these reach the end of the road about the end of this decade.

Whether euclyapts will do this is open to doubt, and no-one is promoting eucalyptus trees as the

salvation of the West Coast timber industry. But trial harvestings of earlier plantings give some ground for hopes that they will provide some premium timber at a distant future date. Large areas once under native forest have been "converted” piecemeal to pines or Douglas fir. partly to provide continuity of employment for millers when the podocarps are gone. In many cases these plantings were bitterly opposed by conservation groups, and some foresters agree with these groups that part of the area now in pines would be better converted back to natives. Their objections are on pragmatic grounds — large quantities of pine timber on the West Coast could be an embarrassment. Neither Canterbury nor Nelson, the nearest markets, are expected to require them because these areas can supply, at lower cost, all the homegrown bread-and-butter timber that they need. The economics of shipping out West Coast logs for pulping are dubious, and forestry scientists rule out, at this stage, an overseas market because of the cost of getting the logs to a main port. The West Coast has no deepwater port. Another problem likely to hinder any sales of pine to Canterbury is the needle-cast fungus, dothistroma, which is rife on the West Coast. Canterbury is one of the few areas still free of this disease. which kills the needles of- young trees and reduces the growth rate. It is unlikely that timbergrowing interests in Canterbury would take kindly to any deal likely to introduce this pathogen to their plantations.