Cool burning in the hot tropics
Paul and Meg Bird
'Block B'
Darwin River NT
Paul and Meg Bird and their four children, along with Michael Christie, are the first settlers on a 40-hectare bush block 60 kilometres outside Darwin. They purchased the land in 1991 after spending 18 years on Yirrkala Aboriginal community in east Arnhem Land. Paul is a plumber and the family maintains 'Block B' as bushland, with vine thickets and rainforest. 'Block B' backs onto the catchment for the Darwin River Dam, which is natural bushland. Each year as the dry season intensifies, the land dries out. Fires that start between June and September are very intense and can do a lot of damage. Before moving onto the block, the Birds observed the damage done by dry season wildfires to the native flora and fauna of the area. Given the predictable nature of the tropical climate, they were keen to adapt their management practices to suit the conditions of the area. Knowledge of the tropical climate, weather forecasts and observations of the conditions on-ground are three elements that are vital for the success of cool burning. |  |
'Our block has several vine thickets and there's a spring with a wet rainforest' said Paul.
'We were really concerned with keeping the hot fires out of those areas. And of course we wanted to protect our own infrastructure too.
'Timing is absolutely critical when using fire as a tool to look after the bush. There's only about three or four weeks when you can do a cool burn. If you leave it later than that you're going to have a problem because you haven't got the dew and it gets too dry.
'It's very important that the fires go out overnight. We start burning in the late afternoon and as the sun goes down, so does the fire. The night brings dew, which snuffs out the fire completely.
'When the wet is tapering off and the country starts to dry out, we begin looking at weather predictions. We need to know about wind direction, moisture content and making sure it won't rain.
'When we have that information, we check the dew on the ground in the morning and look at the fuel load to see if it's dry enough to burn. The final decision is made on what we see when we're walking around.
'The last step is getting a permit from the Bushfire Council. The council gets a detailed weather forecast for the day and the week and if the forecast isn't suitable, it won't issue us a permit.'
The Birds' four children were all born on Yirrkala Aboriginal Community and learned about some of the environmental indicators that Aboriginal people use. Paul believes it is unfortunate that western science doesn't fully recognise the depth of knowledge that Aboriginal people have about climate and the physical characteristics of the landscape.
'We use the information that's available to us, like weather forecasts, rather than the intimate knowledge that Aboriginal people have' said Paul.
'My kids see indicators that I don't notice when we're in the bush. If they're looking for yams, they don't necessarily look for the yams straight away; they look for the indicators instead.
'There's isn't a flower or other indicator that we look for to show us when to start burning - we have to rely on understanding weather patterns instead.
'The climate is pretty stable in the tropics - after a certain time of year you know it's not going to rain, at other times it's stormy for several months. When we decide to do the burning, we know the wind isn't just going to blow up like it does down south.'
Adopting cool burning three years ago led the Birds to reconsider the idea of their own property being separate from their neighbours.
'We've realised that you can't just have a little patch - it adjoins the next one and is part of a system' said Paul.
'So we talk to the neighbours and look at it as one big piece of land when we're planning the cool burning. We've formed the Darwin River Hills Landcare Group and most people are involved in that, at least informally.'
The benefits of cool burning are apparent after just three years. Biodiversity is increasing, problem weeds are being reduced and the vine thickets and rainforest areas are in better health, as well as increasing in size.
'The vine thickets and rainforest stay wetter for longer, so if we burn early we can burn from the edges of them and not damage them' said Paul.
'Since we've been doing cool burning and we haven't had the big hot fires coming through, we're getting more of a canopy over the early burnt areas. The grasses are different and we're getting more shade in certain areas. By regenerating the canopy, some of the feral weeds that are problems in Darwin are being overtaken by the natives again.'
'The main long term benefit is that the native plants and trees survive and the new trees have a chance to grow' said Meg.
'If a hot fire comes through every year, it reduces the size of the vine thickets and the trees that are lost on the outside are never replaced. Even in the three years that we've been doing it, we can see the new trees growing that previously wouldn't have had a chance of surviving. The area is growing rather than shrinking.'
Paul and Meg believe it is vital to take climatic conditions into consideration when planning any land use activities, from introducing new pasture species through to subdividing for settlement, due to potential problems and unforeseen effects.
'There is a big problem up here with introduced pasture species such as mission grass and gamba' said Paul.
'They stay green for a lot longer than native grasses and carry a much heavier fuel load. In areas where they've spread you can't do an early burn because the grasses haven't dried out enough. By the time they are dry it's August or September, and by then if they catch fire they really go up and can be very dangerous.'
'We recently challenged a local subdivision proposal because it was unsuitable for our tropical climate' said Meg.
'Some of the land on the subdivision goes underwater every year in the wet and we believed the developer wasn't taking the climate into account properly. We don't mind people subdividing but it needs to be done sensibly and looking at the land the way it is and the climatic conditions over the year.
'The longer you live in a place the more you learn about the weather patterns. You need to look at the land as a whole and being part of a larger area. The plants and the animals and us are all in there together and we're all connected.'