New Zealand Journal of Botany abstracts
Godley Review
Winter leaf loss in the New Zealand woody flora
Matt S. McGlone
Roger J. Dungan*
Graeme M. J. Hall
Robert B. Allen
Landcare Research
P.O. Box 69
Lincoln 8152, New Zealand
Abstract Approximately 27 species (c. 5%) of the
New
Zealand woody flora have a marked loss of leaves in winter, although
only
10 species are consistently fully deciduous and no extensive vegetation
type
is dominated by them. There are no summer deciduous species. The
deciduous
habit appears in most cases to have evolved independently within New
Zealand
from either ancestors or immigrants with short leaf life spans. New
Zealand
deciduous or semideciduous species typically lose substantial numbers
of
leaves throughout the growing season, and leaf loss is often gradual
throughout
winter but accelerated by frost. The deciduous habit in New Zealand
tends
to be a leaf- or shoot-level feature reflecting short leaf life spans
and
winter stress on individual shoots, rather than a systematic feature of
the
canopy-level organisation of the plant. Degree of deciduousness varies
with
taxon, plant age, climate, and soil fertility. A physiological study of
co-occurring
fully deciduous (Fuchsia excorticata) and semideciduous (Aristotelia
serrata) trees in the South Island established that higher
growing-season
productivity of Fuchsia compensated for carbon gain forgone
over winter.
However, Fuchsia was significantly favoured over Aristotelia
only on the coldest sites. Aside from some inland basins of the South
Island,
New Zealand has milder winters than those that favour deciduous taxa
globally,
and this is the primary reason for the low incidence of deciduous
species.
Even so, a number of deciduous species are common throughout. New
Zealand
deciduous trees and shrubs are typically fast growing and are
characteristic
of seral or forest marginal habitat on nutrient-rich soils developed in
recent
alluvium or debris. The relatively low nutrient status of most New
Zealand
forest soils makes a deciduous phenology, with its necessarily high
turnover
of nutrients, less competitive than a nutrient-conserving evergreen
phenology.
Deciduous species are often also divaricating, or have close relatives
that
are, and share a preference for nutrient-rich soils with this growth
form.
This strong relationship between the two habits suggests both are, in
part,
adaptations to stressful climates by plants with high-productivity
leaves..
Keywords phenology; leaf life span; evergreen;
deciduous;
New Zealand; divaricating; Aristotelia serrata; Fuchsia
excorticata
B03046; Online publication date 30 March 2004; Received 28 October
2003;
accepted 4 February 2004
©New Zealand Journal of Botany, 2004, Vol. 42: 1-19
0028-825X/04/4201-0001 © The Royal Society of New Zealand 2004
PDF file of entire paper: Print-quality
(164K) |
screen-quality (124K)
This year's abstracts |
Journal home page |
All abstracts |
Publishing home page
