Gamba grass (Andropogon gayanus): loathed by environmentalists and bushfire fighters alike. Called the “green bulldozer” because late dry season gamba grass fuelled wildfires burn so hot that native trees and vegetation are killed, eventually leaving a mono culture in which nothing else can grow. Bushfires NT and NTFRS carry out most of their prescribed burning in the early dry season. At this time, fires burn in a mosaic pattern around sensitive areas such as creeks and billabongs and still green patches, providing safe refuges for wildlife and protecting these areas from hot late season wildfires. Later in the season, dry south easterly winds increase in strength, grasses cure (dry out) and fires become hotter and more dangerous. Native spear grass (Sorghum spp.) cures early in the dry season while mission and gamba grasses are still quite green. Fires at this time of year burn native grasses in the desired mosaic pattern, but merely cause gamba and mission grass to fall over without burning. The fallen grass now dries fairly quickly and can carry a second fire, less intense than the first. If this second fire occurs early enough while there is still moisture in the soil the gamba grass will sprout from its unharmed root mass. Late in the season this new growth will dry and support a third fire. Volunteer bushfire fighters are being called out to more frequent fires, often in the same areas. These fires are becoming hotter and more dangerous to manage. Just look at the number of GFU’s with scorched paintwork at the end of the bushfire season compared with just a few years ago. The NT Government finally declared gamba grass an invasive weed in late 2008. You should have heard the cheer that went up when this was announced at the firies’ Christmas do at Livingstone VBB depot in November. This means that gamba grass can no longer be planted and must be eradicated or controlled, depending on the area. There are a lot of blocks heavily infested with this scourge; the amount of radiant heat produced by a fire in fully cured gamba means that a 4 metre break around assets will not give adequate protection. You can always widen the break, but wouldn’t it be better to get rid of this grass completely from your property? The environment and your local volunteer bushfire brigade will love you for it. Our native grass has fuel loads from 4-6 (6 is very unlikely) tonnes per hectare and gamba up to 30 tonnes per hectare, on average 15-18. The kW energy in native grass is 4100 and gamba 48000, so 11 times the intensity. Follow the link below for the NRETAS site of gamba grass and see the photos for identification and how it burns.
NRETAS website: Gamba grass A PDF version of this page can be downloaded in the Attachments section at the bottom of this page.  This photo of a fire unit almost hidden in gamba grass
courtesy RFCO Sue Whatley, BFNT
 Above & Below: These photos were taken about 4 hours after a back-burn to a wildfire in the Rum Jungle area, 4 May 2008. The still green gamba grass has fallen over without burning.
 The next lot of photos, courtesy Bushfires NT, show how gamba grass burns
  The next two photos courtesy "Davo" McLachlan
Lambells Lagoon Volunteer Bushfire Brigade
| Photos
The first group of photos show how gamba grass starts along roadways and if left to grow it quickly invades the surrounding bush. The first five photos were taken February 2009 on Old Bynoe Road, Berry Springs. The grass was sprayed with glyphosate the same day      The next lot of photos, courtesy Bushfires NT, show how gamba grass burns
   Below: 2 days after an intense fire the gamba grass is sprouting already and a victim of the same fire - wildlife can usually escape from bushfires
Photos courtesy Sue Whatley, RFCO Vernon   |
