The growth of some New Zealand trees

Abstract

Seasonal growth of the New Zealand species Fuchsia excorticata, Aristotelia serrata, and Hoheria glabrata (deciduous), and Nothofagus menziesii, N. fusca, and N. solandri (evergreen) was compared with that of the introduced deciduous Acer pseudoplatanus. Native species at different altitudes began growth each spring in the warmest situations first. Younger plants had a longer growing season and made more extension growth each year than mature trees. The non-growing season appeared to be a period of real dormancy, for morphologically distinct buds were laid down. At all ages in Acer and the native deciduous species the season's growth was continuous, but in the Nothofagus species this was true of only first-year seedlings and mature trees. At intermediate ages there were two flushes each season. Growth rings were annual, except in shoots which flushed twice. Most of those made two rings in the season. Leaf fall was confined to autumn in Acer. In the native species, leaves were shed sporadically through the year, but most fell from the deciduous species in autumn, and from the Nothofagus species in spring. In mature trees of all species the season's growth is predetermined by the number of leaf primordia in the bud, and stops by mid-summer. The onset of seasonal dormancy is therefore concluded to be autonomously controlled In young trees, and even seedlings of Acer, it is probably similarly determined! since they also stop growing in summer. On the other hand, as young trees and seedlings of the native species grow until autumn, the onset of dormancy is probably determined by the environment. The start of the growing season in all species is controlled mainly by temperature. Leaf fall in Acer is under photoperiodic control, but in the native deciduous species it is temperature controlled. In Nothofagus it may be a direct consequence of bud-break. © Taylor & Francis Group, LLC.