THE EFFECT OF LOW ROOT TEMPERATURES ON THE GROWTH OF 
MOUNTAIN FOREST EUCALYPTS IN RELATION TO THE ECOLOGY OF 
EUCAL YPTUS NITENS 
E. A. Chesterfield 1 , M. J. McCormick 2 and G. Hepworth 3 
■National Parks and Public Land Division, and 2 Natural Resource Systems Division, 
Department of Conservation and Environment, PO Box 41, East Melbourne, Victoria 3002 
3 Biometric Services, Department of Agriculture, PO Box 500. East Melbourne, Victoria 3002 
Chesterfield, E. A.. McCormick. M. L. & Hepworth, G., 1991:12:31. The effect of low 
root temperatures on the growth of mountain forest eucalypts in relation to the ecology 
of Eucalyptus nitens. Proceedings of the Royal Society of Victoria 103 (2): 67-76. ISSN 
0035-9211. 
To compare the response of four montane eucalypts to low soil temperature, seedlings 
of Eucalyptus regnans, E. delegatensis, E. fastigata and four provenances of E. nitens were 
treated for 100 days in a glasshouse. Mean ambient air temperatures varied between 15°C 
and 29 a C while temperatures within the root zone were held in the vicinitv of either 5°C or 
10°C. 
All species grew significantly better at the higher temperature for all variables measured. 
Differences in stem diameter, root length, root and shoot dry weight were consistent between 
species at both temperatures. Growth of E. regnans and E. nitens was similar overall. For 
most variables both species grew significantly better than E. delegatensis, which grew sig¬ 
nificantly more than E. fastigata. For height growth there was a highly significant interaction 
between species and temperature. At both temperatures, E. regnans made significantly bet¬ 
ter height growth than all other species. At the higher temperature, E. fastigata grew 
significantly taller than E. nitens and E. delegatensis but, at the lower temperature, E. nitens 
grew significantly taller than E, delegatensis and E . fastigata. Comparing the difference in 
height growth. E. fastigata and E. delegatensis were reduced substantially more than E. 
nitens by the cool root environment. 
Eucalyptus nitens has a restricted distribution for a species with outstanding vigour. 
This may be related to a fire regime which also encourages the development of rainforest 
understories, and cool, heavily shaded soils. The implications of topography and fire regime 
on understorey type and soil temperature are discussed in relation to the ecology of E. nit¬ 
ens. 
FOUR TALL forest eucalypts in the mountain 
forests of southeastern Australia have overlap¬ 
ping distributions in regions with mean annual 
rainfall exceeding 750 mm. Eucalyptus delega¬ 
tensis R. Baker and E. regnans F. Muell are 
dominant species over extensive highland areas 
of Tasmania and Victoria (Eldridge 1972, 
Boland & Dunn 1985). E. delegatensis extends 
into southern New South Wales, replacing E. 
regnans above 1000 m over the greater part of its 
range. E. nitens (Deane & Maiden) Maiden and 
£. fastigata Deane & Maiden occupy similar 
latitudes in northern New South Wales (Sherry 
& Pryor 1967, Tibbits & Reid 1987). Both spe¬ 
cies extend south into East Gippsland, Victoria, 
while scattered stands of E. nitens also occur 
westward along the Great Dividing Range and 
into the Central Highlands. The elevation range 
of both species is influenced by latitude but, in 
Victoria, optimum development occurs at or 
near the lower limit of winter snow. 
The growth rates of E. nitens are recognised as 
being greater than those of E. regnans in plan¬ 
tations up to 15 years (Pederick 1976), and 
planting trials indicate that E nitens can be suc¬ 
cessfully grown in cool mountain areas receiving 
an annual rainfall of over 1000 mm (Turnbull & 
Pryor 1978). Despite this, the natural distri¬ 
bution consists mainly of small, disjunct stands 
(Pederick 1979) that may be enclaves of for¬ 
merly more widespread populations. 
Three broad regional forms of E. nitens have 
been recognised on the basis of leaf shape 
(Shepherd et al. 1976). The northern New South 
Wales form occurs near Mt Ebor and Barrington 
Tops. The southern New South Wales and West 
Gippsland forms both occur in Victoria. They 
differ in their morphology and vigour (Pederick 
1979) and in some aspects of their physiology 
(Pederick & Lennox 1979, Tibbits & Reid 1987). 
The West Gippsland form is fast growing with 
strongly glaucous juvenile leaves and occurs 
67 
