Last month I attended a conference at Asimolar on the Monterey Peninsula, south of San Francisco in the United States. It is a place that holds a special interest for New Zealanders as it is the home of two of our most widespread introduced trees: Monterey pine (Pinus radiata, commonly known as radiata pine) and Monterey cypress (Cupressus macrocarpa, commonly known as macrocarpa). Amazingly, both are regarded as endangered species in their home territory.
We visited California at the height of summer, with daytime temperatures in the high 30s (Celsius) in most places. But in a narrow strip close to the coast, from San Francisco south to Monterey, the temperatures are much cooler, often with daytime fog and mist. Summer rainfall is low, but the trees gain enough moisture from fog condensing on the branches and dripping on to the ground. The soils are infertile – mainly sand dunes or solid granite – and the trees look as if they are struggling to survive. The small natural population of Monterey pine and Monterey cypress are a relic of forests that were widespread in the ice ages, but retreated to the cool, foggy Monterey Peninsula as temperatures warmed during the last 10,000 years.
Radiata pine is the basis of the forestry industry in New Zealand – indeed, it is the only plant species apart from kauri to have its own entry in Te Ara. It grows much more vigorously in temperate climates than in its home area, and is the most widely planted pine in the world, with large plantations in Australia, Spain, Kenya and several countries in South America. It was first introduced into New Zealand in the 1850s, and the oldest known tree was planted at Peel Forest in 1859.
As New Zealand’s land was developed for farming, there was an urgent search for quick-growing trees that could be used for shelter belts, firewood and timber. The Colonial Botanic Garden (now Wellington Botanic Garden) was established by James Hector in 1868 to evaluate the most suitable trees to introduce into New Zealand, and to provide seeds and plants. Within a decade it had become clear that radiata pine and macrocarpa grew exceptionally well under New Zealand conditions, and many of the older trees in gardens and farms around New Zealand were originally raised and distributed from the Botanic Garden in Wellington.
Plantations of radiata pine were not developed until the 20th century, when it was realised that good-quality timber could be produced if the trees were systematically pruned. Macrocarpa is used in New Zealand mainly for shelter belts and firewood.