New Zealand timberlines. 1. Growth and survival of native and introduced tree species in the Craigieburn Range, Canterbury

Abstract

Experiments in the Craigiebum Range compare germination, growth, and survival of mountain beech (Nothofagus solandri; var. cliffortioides) and exotic timberline species through an altitudinal range of 900–1780 m and three levels of shade. All species germinate at all altitudes but growth rates are inversely related to altitude. In un shaded plots, beech seedlings survive only at or below 1300 m. Shaded beech seedlings at 1600 m had heavy initial mortality, and eventual1y died because of repeated frosting and winter die-back of shoots. Even at 1300 m plants tend to die back once they grow above surrounding shelter, thereby forming krummholz.

Unshaded seedlings of Picea engelmannii are severely damaged by early summer frosts; and from 1450 m upwards, this prevents them from growing taller than surrounding shelter. Pinus contorta grows best in full sunlight. and there are vigorous seedlings at 1780 m; however, wind-exposed plants at 1600 m are developing krummholz forms, because of winter death of their taller shoots. The tropical-subalpine P. hartwegii is surviving up to 1450 m. Saplings of Eucalyptus pauciflora and E. coccifera are growing vigorously at 1300 m and seedlings will probably survive at 1450 m, but not exceed the height of surrounding shelter.

Keywords:

• timberline
• mountain beech
• Picea engelmannii
• Pinus contorta
• Eucalyptus pauciflora
• shade
• winter die-back
• krummholz

In this series of papers, terms arc used as follows: Alpine timberline: used in a broad sense for the upper limit of trees and forests on mountains, Inverted timberline: where forest has a lower boundary against the treeless floor of a mountain valley, Krummholz: stunted and deformed trees above the forest limit. Scrub: woody vegetation consisting of plants inherently of shrub form, Tree limit: the extreme upper limit of trees, krummholz, or shrubs more than 2 m tall, Alpine and subalpine: the vegetation belts above and below tree limit.

In this series of papers, terms arc used as follows: Alpine timberline: used in a broad sense for the upper limit of trees and forests on mountains, Inverted timberline: where forest has a lower boundary against the treeless floor of a mountain valley, Krummholz: stunted and deformed trees above the forest limit. Scrub: woody vegetation consisting of plants inherently of shrub form, Tree limit: the extreme upper limit of trees, krummholz, or shrubs more than 2 m tall, Alpine and subalpine: the vegetation belts above and below tree limit.

Notes

In this series of papers, terms arc used as follows: Alpine timberline: used in a broad sense for the upper limit of trees and forests on mountains, Inverted timberline: where forest has a lower boundary against the treeless floor of a mountain valley, Krummholz: stunted and deformed trees above the forest limit. Scrub: woody vegetation consisting of plants inherently of shrub form, Tree limit: the extreme upper limit of trees, krummholz, or shrubs more than 2 m tall, Alpine and subalpine: the vegetation belts above and below tree limit.