Disturbance: Ecological Burning
We generally burn in autumn after there has been some good rain to moisten the top soil. We usually start burning during the end of the fire permit season in late March and aim to finish by mid-April. We need a several days of dry or windy weather to dry our dense vegetation to ground level. We then select days with minimal wind, often with a very light south-easterly in the morning and switching to a north-westerly sea breeze around lunch time. Autumn burning is preferable for most orchid species because the majority of their leaves, flowers and fruits are still dormant then. Spring burning can be very problematic as the ground can be flooded or very wet, which makes it difficult to use our tractor and its fire pump without damaging the ground.
To disturb an area of sandy woodland (TASVEG: DAC) that has a sparse number of trees, we sometimes slash the area, rake the slashed vegetation into windrows and burn windrows into the breeze.
For larger areas of wet heathland (TASVEG: SHW), slashing fire breaks is a major project. Slash debris can be raked into windrows in fire breaks, and burnt in strips. More recently we have been throwing slash debris into the burn area and wetting down the fire breaks on the day of the burn.
Our preferred method for burning larger burn units is to back-burn into the breeze. We gradually light the down-wind edge, keeping a line of flames approximately at right angles to the wind direction. This works well in the afternoon after the sea breeze has set in. Earlier in the day we are always alert for wind changes.
To speed up a burn, we can "round up" the fire by lighting around all edges which then tends to pull the flames towards the centre of the burn unit. Some of the edges will be burning down wind, which creates much more smoke.
At the end of a long day, the last burn unit can be rounded up very safely, with everything around it already blackened.
Whenever we are burning we park Phil’s home made fire fighting unit close by. Rakes, forks and watering cans are our standard tools. We can use the drip torch to light around quickly, and the fire pump to put out small to moderate sized spot fires when necessary. We wear bright yellow, flame-proof overalls for our own protection and to send a reassuring message to people who see us from the road.
We have developed several procedures that aim to ensure a safe and contained burn. We need to be constantly prepared for the wind to change direction, and alert to unexpected increases in wind strength. If the wind takes the fire in an unexpected direction, we rely on our fire break to stop it, and do not attempt to intervene unless it's completely safe. We are constantly vigilant in case flying embers, most commonly bracken heads, start spot fires outside our fire breaks. Lastly, we have a "zero tolerance" of smoke in burn units after the fires have passed. We use watering cans to wet down any smouldering embers or vegetation, commonly duck or potoroo nests, and remain vigilant until the end of the day. We are always present on site the following day to double check that nothing is still smouldering.