New Zealand needs more trees, whether native or exotic, because forests benefits the environment in so many ways. Most important is their ability to reduce flood flows and soil erosion on our steep unstable hill country. There are many striking examples that aptly show how effective forests can be reducing the extent of landslides when compared to pasture on the same topography.
The problem is that the way we harvest our exotic forests destroys these protective functions. Despite the existence of an "Environmental Code of 'Best' Practice" too great an area of steep forests end up as a trashed landscape littered with slash, log ends and bare soil. Radiata pine takes 30 years to mature. Therefore roughly 1/30th of the NZ's area of radiata plantation (nearly 60,000 hectares) is clear-cut every year. The landscape remains stark and vulnerable for at least five years until a new forest is established. Any high rainfall storms on hill country can cause more erosion in logged forests than pasture because so much soil and debris is exposed.
In the past year China's demand for timber has reinvigorated forestry, not before time, as the previous years of dismal returns nearly crippled the industry. Unfortunately, the renaissance has coincided with a period of exceptional storms. The inevitable result has been landslides of forest debris flooding rivers and silting local estuaries. The damage is all too visible around Nelson and the Coromandel hill country.
Surely it's time the forestry industry lifted its game. The logging of whole hillsides in one swoop is frontier forestry. Our forest owners could show a little more sophistication on sensitive landscapes by better applying their own code of practice. Additional techniques such as using smaller felling areas, and even maintaining a continuous forest cover, are standard practice overseas but are implemented here by only a few enthusiasts. They may cost a little more but the environmental gains would be enormous. Better the industry takes the initiative itself than wait for local Councils to force more inflexible rules.