Corangamite Group Officer, Larpent Fire Brigade member and President of Dairy Farmers Victoria Mark Billing
The green drought conditions across the state, fuelled by a shortfall of rain, has the potential to increase the likelihood and intensity of fires this fire season.
Green drought occurs when there’s enough rainfall to keep the top layer of grass and shallow-rooted vegetation such as weeds green, but the underlying soil remains too dry to sustain new plant growth.
This can happen even if there has been recent rain because the water may not penetrate effectively to the root systems of plants.
Green drought conditions are unusual but not unheard of. While there are similarities between green drought and drought, green drought can create an illusion of safety through its ability to mask the underlying dryness. When driving past a green paddock or forest area in an area impacted by green drought, you could be forgiven for thinking the fire risk is low in that area.
However, vegetation that appears healthy may still be dry and more susceptible to ignition because of insufficient water. As plants use up the small quantity of stored moisture in the soil, they lose their resilience making them more flammable and causing them to dry out faster. In addition, the tendency for grass
and weeds to grow on top of existing dry or matted fuel during green drought conditions creates a bigger fire risk when the top layer dries out, providing additional fuel and encouraging fires to burn hotter and longer.
ECHOES OF ASH WEDNESDAY
While Victoria experienced a dry autumn and winter this year, the impact has been most notable in the far west and south-west of the state which experienced record levels of rainfall deficit. The AFAC summer outlook for the fire season indicates an increased risk of fire in these areas because of the high level of uncertainty in the rainfall outlook and the increase in the amount of dead and
dry plant material in forests.
In the state’s south-west where the effects of green drought are particularly evident, Corangamite Group Officer, Larpent Fire Brigade member and president of Dairy Farmers Victoria Mark Billing laments at how dry some of the paddock and forest areas are at present compared with previous years.
“The wind has caused a high evaporation rate of water that has hit the ground,” Mark said. “Underlying soil dryness is a huge issue, particularly in the western Otways. Any rain we did get in spring didn’t penetrate the canopy floor.
“I was 15 when Ash Wednesday happened, and I reckon that’s the last time I’ve seen the bush in the Otways as dry as it is now leading into the fire season. Anything that isn’t dry now is going to turn pretty quickly.”
It’s a similar story further south. As he looks out over his paddocks, semi-retired farmer and Winslow and Yarpturk Fire Brigade volunteer Owen O'Keefe says even though visually his property looks very green and fresh, that’s only because of surface moisture.
“The deeper you go into the soil profile it’s very dry; deep-rooted perennials are really dying out,” Owen said.
“I’ve been around a while, and like Mark I reckon the current season lead-up is very similar to Ash Wednesday. The Grampians, northern parts of the Otways, forests over Casterton way and along the South Australian border are as dry as a chip. It’s been a terrible winter for pasture growth and the grass is very short.
“If we get some good rain we might be OK, but if we don’t the first burst of hot weather and northerly winds will rapidly dry out any grass. If a fire gets going on shorter grass it’ll burn very fast. In the right conditions fire will almost flash across short grass like burning liquid fuel.”
Further north near Hamilton, Captain of Byaduk Fire Brigade and sheep farmer Will Kinghorn said while they’ve had more grass growth compared with last year, like Owen, he believed the low soil moisture levels coupled with any wind will cause this grass to cure quickly.
“Our biggest risk going into the season is our non-farming and grassland areas such as bushland, forests and plantations,” Will said.
“We’re located between a state and national park and the bushland and forest floor are pretty dry. There’s none of the moisture in the ground you would normally see at this time of year and composting of forest fuel hasn’t happened.
“The lack of soil moisture makes the trees less resilient. It would burn pretty easy if it went up today – this wouldn’t normally be the case for this time of year.”
SOME FIRE WATER SOURCES ON KNIFE'S EDGE
Not only do the current conditions have implications for fire behaviour and suppression, but the lack of surface water and run-off means important fire water sources are well below normal levels.
“By October we were already 100ml down on rainfall compared to the same time last year, and last year was a dry year,” Owen said. “A lot of dams are low, creeks are dry. People haven’t been able to replenish their rainwater tanks. Water is going to be a huge issue if we are unlucky to get a hot, dry fire season.”
“Colac and surrounds has had the lowest rainfall on record,” Mark added. “That rain in October was great to give the pastures a boost, but we just didn’t see the usual run-off. We’ve been up checking over the fire dams in the Otways and they’re pretty low.
“In my time on the land, the only comparison I can make is with the 2006 and 2013 droughts, but really we're in unchartered territory."
For brigades in Will’s patch, it remains on a knife’s edge.
“Usually between April and September you’ll have an inch or two of rain in one downpour, but an inch is the most we had in total,” he said.
“There’s been very little run-off to fill up the dams here, many of which are fire dams. It’s going to come down to how much rain we get before the season kicks off.”
IMPACT EXTENDS BEYOND FIRE RISK
With many CFA members also working on the land, green drought can have far-reaching consequences and cause significant financial and personal stress.
Although his farm is in a neighbouring shire, unlike Will, Ardachy Fire Brigade firefighter Duncan Macgugan has had very little pasture growth this year and had to buy in significant supplementary feed to keep his stock going.
“The fire season outlook and current conditions will see many volunteers who are farmers heading into the fire season with a high level of background stress,” he said.
“Most livestock producers were already in a tough position as we got to autumn this year, only to be confronted by the worst seasonal conditions in 57 years.
“Costs have increased significantly in the past two years. In addition to extra feeding, producers have been forced to sell stock.
“Like many we have been working seven days a week feeding, with little time available to complete other work.”
This year is the first year Mark has had to buy in feed. He says the ‘croppers’ are also doing it tough due to the conditions.
“The grain growers have copped the vagaries of this year’s weather as well and there have been a lot of crop failures,” he said.
“A lot of farmers will be getting as much of their feed squared away to get it conserved before the grass cures off and the fire season really hits.
“In terms of the impact of green drought on the outlook for the fire season and the farming sector, it’s a case of planning for the worst and hoping for the best."
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