Author:
Clarke Peter J.,Davison Elizabeth A.,Fulloon Lindsay
Abstract
The germination requirements of a broad spectrum of common species found in
grassy woodlands and forests in the New England region of northern New South
Wales were tested in a series of replicated growth-cabinet experiments. The
effects of dark/diurnal light and smoke/no smoke were measured on 65
species in an orthogonal experiment, 21 of which were retested after storage
for 12 months. The effect of storage for several years was also assessed under
a diurnal light regime. In addition, the effects of preimbibition heat
(80˚C), and chilling on germination were also measured. A single
temperature regime (15˚C night/25˚C day) was used in all
treatments for comparative purposes. Most species had high viability and
germinability under a diurnal light regime. Small shrub species included,
however, a large proportion of species with entrenched dormancy. Light
enhanced germination of 21 species significantly, whereas dark stimulated
germination of only eight species. Heat and cold treatments also stimulated
some germination but more often inhibited germination or produced no effect.
Smoke stimulated germination, relative to other cues, in only one species
(Ajuga australis) and more often inhibited germination
or produced no effect. The relationship between variation in germination
(stimulation, no effect or inhibition) of species in six growth-form classes
was tested by using contingency tables for each treatment. No significant
relationship between growth form and the effects of light, smoke or chilling
was detected. Preimbibition heat effects were, however, significantly
different among growth forms. Subshrubs showed a higher than expected
proportion of species with a heat stimuli while herbaceous species showed a
higher than expected proportion of species inhibited by preimbibition heat.
Germinability generally increased in herbaceous species when stored at ambient
temperatures while it remained relatively constant in woody species.
Conversely, viability decreased in herbaceous species but remained relatively
more constant in woody species. The effects of seed storage and high
germinability suggest that most perennial herbaceous species have transient or
short-term persistent seed banks. Germinability, with and without cues, was
also negatively correlated with increasing seed size and larger growth forms.
These traits might be related to the need for woody species, with soil-stored
seed banks, to spread establishment risks in an environment where herbaceous
competition and herbivory are likely to be important selection factors.
Subject
Plant Science,Ecology, Evolution, Behavior and Systematics
Cited by
90 articles.
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