The Growth Forms and Ecology of Nothofagus solandri at the Alpine Timberline, Craigieburn Range, New Zealand

Abstract

The growth forms of N. solandri trees at the alpine timberline in the Craigieburn Range, Canterbury, New Zealand, are described. These forms arise in response to winter conditions, the effect of winter desiccation, frost and snow, being particularly important. The main tree responses recognized are foliage death and shoot dieback, stem deformation and epicormic branching. Vegetative proliferation is more important at timberline than at lower altitudes. Many timberlines lacking stunted growth forms have developed in response to fire. Those which are not caused by fire are diverse with several distinctive growth forms present. It is considered that the term krummholz is inappropriate to the New Zealand situation; subalpine woody plant growth can be broadly described as erect trees, crippled trees and shrubs. Although the timberline ecotone in these New Zealand angiosperm forests is very narrow compared to those of many Northern Hemisphere gymnosperm forests, the climatic conditions experienced in the timberline ecotone modify and deform tree growth in a similar manner.