Abstract
Marked interspecific differences in frost resistance were shown to exist between eucalypt seedlings grown
in reciprocal field transplant trials conducted at a frost hollow on Snug Plains, south-eastern Tasmania.
Populations of the six eucalypt species tested naturally inhabited the margins and base of this frost
hollow. A growing season frost of - 5.5°C caused substantial damage to E. delegatensis, E. pulchella,
E. urnigera, E. johnstonii and E. coccifera but only slight damage to E. gunnii. A winter frost of
- 10.5°C caused markedly less damage than the growing season frost, suggesting that appreciable
hardening occurs in winter and that growing season frosts may play a significant role in determining
the distribution of subalpine eucalypts. E. pulchella appeared more resistant to growing season frosts
than E. delegatensis while the reverse occurred in all but one of the experimental gardens during winter
frosts. The reasons for this reversal and its significance are discussed. Frost chamber experiments
confirmed the major differences between species in frost resistance and the importance of hardening.
The reciprocal transplant trials suggested that seedlings from subgenus Symphyomyrtus were more
frost resistant than those from subgenus Monocalyptus in sites prone to waterlogging. This was sup-
ported by frost chamber trials in which a significant interaction between frost resistance and waterlog-
ging was demonstrated. Species from subgenus Monocalyptus showed a reduced ability to harden under
waterlogged conditions compared with species from subgenus Symphyomyrtus. This interaction may be
of ecological importance since species from subgenus Monocalyptus do not occur in cold, waterlogged
sites at Snug Plains. The present and previous experiments suggest that the distribution of subalpine
eucalypts is dependent upon the interaction of a range of factors including the severity of winter frosts,
resistance to growing season frosts, the suitability of the site for frost hardening and the degree of
waterlogging.
Subject
Plant Science,Ecology, Evolution, Behavior and Systematics
Cited by
21 articles.
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