Nothern Territory University
Aspects of the physiological and fire ecology of Gamba
Grass
2001
Summary | Aims | Progress | Utilisation and application of research |
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Natalie Rossiter in front of a stand of gamba
grass. The tussocks can reach a height of 4 metres, and produce
very high fuel loads for fires in the savannas
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Gamba grass (Andropogon gayanus) is a vigorous perennial
species that has been selected as a pasture species for its
competitive abilities and growth rates. However, concern has been
raised about its recent spread outside of pastoral systems, and its
occurrence is increasing in upland savannas and along riparian
habitats.
At present there is little information on what effect the
replacement of native grasses by exotic species such as Gamba grass
may have on ecosystem processes such as fire regime and water and
carbon cycles. This project will examine three related aspects of
gamba grass ecology (1) plant physiological characteristics,
particularly assimilation rates; (2) above-ground biomass
production (fuel load), and (3) fire regime characteristics.
Results obtained on gamba grass will be compared with the native
grasses Sorghum intrans and Heteropogon contortus. The results of
this study will contribute to a greater understanding of the
consequences of altering the composition of the savanna grass
understorey.
The aims of this study are to:
- To determine the physiological mechanisms that allow gamba
grass to accumulate greater biomass than native vegetation.
- To describe the potential changes to fire regimes that may be
caused by the greater biomass production of Gamba grass.
To compare physiological aspects of gamba grass, heteropogon,
and sorghum, the photosynthesis rate, and transpiration rate have
been measured monthly since March 2001.
To compare biomass production (fuel load) between gamba grass
and native grasses, plant biomass has been measured once in the
early dry season (the start of the fire season), and will be
measured again in the mid-dry season.
To determine the effects of gamba grass invasion on fire regime,
experimental fires have be lit in savannas with understoreys
dominated by gamba grass. This work was undertaken at Wildman River
Reserve, in conjunction with the Parks and Wildlife Commission
Rangers. Fuel loads and other fire characteristics such as flame,
scorch and char height, rate of spread and fire temperature were
measured. This information is currently being analysed and will be
used to determine fire intensities and compared with known values
for native grasses.
- The research findings of the project will be used in education
units at NTU on fire ecology and weed management.
- The outputs of the project will also be used in the 'Flames '
and 'Savannas' model.
- The outcomes of this research will assist managers to
prioritise the need for weed control.
Supervisors
Dr Samantha Setterfield
Dr Lindsay Hutley
Dr Michael Douglas
Collaborators
Dr Lynda Prior
Dr Dick Williams
Northern Territory Bushfires Council
Northern Territory Parks and Wildlife
Commission
