The effect of regeneration burns on the growth,nutrient acquisition and mycorrhizae of Eucalyptus regnans F. Muell. (mountain ash) seedlings |
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Authors: | Launonen T M Ashton D H Keane P J |
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Institution: | (1) Department of Botany, La Trobe University, Bundoora, 3083, Victoria, Australia;(2) School of Botany, The University of Melbourne, Parkville, Victoria, 3052, Australia |
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Abstract: | This study was conducted to compare the effects on the growth of Eucalyptus regnans seedlings of unheated soil and soil heated
to different extents (as indicated by soil colour–bright red or black) in burnt logging coupes, and to separate the effects
of heating of the soil on direct nutrient availability and on morphotypes and effectiveness of ectomycorrhizae. Burnt soils
were collected from three logging coupes burnt 2, 14 and 25 months previously and unbumt soil from adjacent regrowth forests.
Compared to unburnt soil, the early seedling growth was stimulated in black burnt soil from all coupes (burnt 2, 14 and 25
months previously). Seedling growth was generally poor in red burnt soil, especially in soil collected 2 months after burning.
However, the concentration of extractable P was extremely high in red burnt soil, especially in soil collected 2 months after
burning. In black burnt soil, extractable P was increased in soil 2 months after burning, but not in the soils collected 14
or 25 months after burning. However, both total P content and concentration in seedlings were increased in all collections
of black burnt soil. Frequency of ectomycorrhizae was high in seedlings grown in all black burnt soils, but the mycorrhizal
mantles were poorly developed in seedlings in black burnt soil collected 2 months after burning. Seedlings were also ectomycorrhizal
in red burnt soil, except in soil collected 2 months after burning. Fine root inocula from seedlings grown in black burnt
soils collected 14 and 25 months after burning significantly stimulated both seedling growth and P uptake compared with the
uninoculated control, whereas the fine root inocula from the seedlings grown in all the other soils did not. These results
suggest that, in black burnt soil, both direct nutritional changes and changes in the ectomycorrhizae may contribute to seedling
growth promotion after regeneration burns. The generally poor seedling growth in red burnt soils is likely to have been due
to N deficiency as the seedlings in these soils were yellow-green and the tissue concentrations of N were significantly lower
than in other treatments.
This revised version was published online in June 2006 with corrections to the Cover Date. |
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Keywords: | ectomycorrhizae Eucalyptus regnans forest burns nitrogen phosphorus |
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