Wet forests and fire

I was privileged recently to visit a beautiful property to complete a Land for Wildlife assessment. Its landscape is not unique for southern Tasmania, but so lovely: mountains at the back and a flowing creek near the front. About two thirds of the property was covered in bushland with other small areas starting to regenerate. The other third was grazing for horses.

With the landowner, I walked to the large area of forest on the slopes of the hills that wend their way eventually to Kunanyi/Mt Wellington. It was a magnificent area of wet forest with occasional large gum trees. There were gnarly twisted trunks of small trees, covered in mosses and lichens. The ground was wet and slippery and the rocks also covered in green growth. The birds were busy, the smell was beautiful and the rain was steadily falling.

Eventually, as is often the case, the conversation turned to the 1967 bushfire, which came through this area. The landowner did not know the extent of the devastation but knows that it burnt through here, as did a subsequent fire in the early 1990s. Little to no evidence of these fires can be seen in this part of the landscape. It is possible that being on a southern slope and being wet forest, the fire did not burn hard and hot through this area. In contrast, you can look to the northerly slopes nearby and still see many large dead trees, which were most likely killed by the ‘67 or subsequent fires.

The current landowner was told that the forest between the creek and a tall cliff may have experienced fewer fires because of the cliff’s sheltering effect. This could help explain why the largest of the property’s blue gums can be found here.

From here, the conversation moved to what should be done about managing the land for fire.

Firstly, the paddock – grassfires can start and spread very quickly.  Grass is fine fuel, burns faster than forest and can generate enormous amounts of radiant heat, though grassfires tend to be less intense and produce fewer embers than bushfires. Grass under 10 cm high poses a much lower risk. On this property, the paddock is partly grazed and mown for hay, providing adequate fuel reduction.  Be aware that grass fires can be started by sparks from tools and machinery and from hot exhaust pipes.

For most of the property, which is covered in wet forest, the question is how to reduce fire risk. Most of the time, when the forest is wet, it will not burn, but in extreme conditions such as the ’67 fire, wet forests will burn.

When fires like this happen (and they are likely to happen again), the ground is exceptionally dry. The fuel on the ground is dry, the bark on the trees is dry. It is hot so the oils in the trees are vaporising into the air. The wet forest can burn and then it may be a very intense fire.

Many people with wet forest on their land are grappling with this problem, which does not have a simple answer. There is not a lot that the owner of a small property can do on their own.

Planned burning is not an easy option for wet forests. When it is safe to burn, wet forests will not burn; the only times they can burn are when you don’t want them to. On the property of my recent visit, the landowner is maintaining tracks around and within the forest and is maintaining dams. These actions are important for less intense fires, but on a catastrophic day, they probably won’t be sufficient.

At the end of the day, owners of small blocks of forest should take care of themselves and their family and, like everyone, they should be preparing around their house and maintaining an active evacuation plan.

So, the advice to this landowner is the same as to most other people:

• Around the property, maintain tracks, firebreaks and water supplies, and keep fire extinguishers at sheds and with machinery.
• Clean up around the house and buildings. Remove leaves from roofs and gutters. Keep shrubs and organic mulch well back from the house. If you have larger trees nearby to your house, then do not have a lot of plants or shrubs underneath. Clear away collections of leaves and sticks.  Keep grass short.
• Follow bushfire preparation advice from the Tasmania Fire Service https://bushfire.tas.gov.au/ and grab opportunities to learn from TFS at workshops and events https://www.bushfirereadyneighbourhoods.tas.gov.au
• Educate yourself. Further resources on fire ecology and burning are provided by Landcare Tasmania https://www.landcaretas.org.au/fire-in-tasmania
• Above all, be prepared, have a plan for you and your family, pets and livestock and practice that plan at least once each year. How do you know what is happening? Internet? Radio? Know where to look and what to listen for.
• Have an evacuation plan. What will trigger your actions? When to prepare, when to leave and which way do you travel? Have a couple of options for travel, if possible, in case one route is already cut off.

The most important thing to remember is that on very high fire danger days be prepared to leave and leave early. Have somewhere to go or just go to the beach for the day. If it is hot enough for a bad fire then the weather for the beach is probably going to be great. And don’t forget to slip, slop, slap.

Alan Hill, fire ecologist and volunteer Land for Wildlife assessor

Banner image by Matt Newton.