- Title:
-
Determination of sustainable fire regimes in the Victorian Alps using plant vital attributes
- Date:
- December 2003
- Organisations
- DSE
- Authors:
- Gregory J. McCarthy, Kevin G. Tolhurst and Karen Chatto
- Location:
- Victoria, VIC, Australia
Overview
The Caledonia River wildfire in January 1998 burned 35 000 ha of foothill, sub-alpine and alpine vegetation in the Victorian Alps. At the time, this was the most extensive fire in Victorian alpine vegetation since 1939. It provided an opportunity to investigate the fire response of many alpine plant species.For each major alpine vegetation community within the fire area, the fire responses of as many species as could be found were collated into a database. The database was then sorted using a plant Vital Attributes methodology (Noble & Slatyer 1980; NRE 1996) which allows identification of Key Fire Response Species. From the Key Fire Response Species can be derived the particular minimum and maximum inter-fire period for each community that ensures that each species extant in the community persists.The period between the minimum and maximum inter-fire periods then defines the range of ecologically sustainable fire frequencies for each vegetation community. This range enables evaluation of current or proposed fire regimes in terms of their ecological sustainability.
The study found that about 75% of alpine species respond very rapidly to fire and are able to regenerate either by seed or vegetatively within two years. It is proposed that this is an evolutionary attribute acquired in response to rapid seasonal changes in the harsh environment.
Although many species appear robust, a few are apparently quite vulnerable to fire. Significant amongst these are the Sphagnum Bogland species - Sphagnum cristatum, S. subsecundum and Richea continentis. Areas of Bogland were substantially burned in the fire and, while small numbers of each species survived, re-establishment of their cover toward pre-fire levels has been very slow. By 18 months post-fire, Richea had shown no signs of regeneration either from seed or vegetatively.
The minimum and maximum inter-fire periods derived in this study suggest that no ecological reasons exist to apply prescribed fire in most of the alpine vegetation communities studied (the only exception being for regeneration of Alpine Ash stands following timber harvesting). Information about weather and fire history indicates that the type of fire experienced in 1998 occurred only once or twice every century. This frequency of fire is considered adequate for providing regeneration opportunities for those intolerant species which otherwise rely on other disturbance events, such as insect attack or senescence of grassland, for their regeneration.
Evaluation of fuel hazard levels indicates no particular imperatives exist to apply prescribed fire for protection reasons.
The potential for soil erosion in alpine environments was seen to be an important reason for not applying frequent prescribed fire. That is, although fire more frequent than once or twice a century may have no significant ecological implications, the reduction of vegetative cover as a result of frequent fires in these vegetation communities may cause significantly increased soil loss.
