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| From: boxhead® | 01/05/2001 12:51:19 |
| Subject: Fire and the Australian Bush | post id: 3647 |
| Hi all, Has anyone had any experience with regular burning of native bushland? It seems to me that the benefits both in terms of the health of the ecosystem and the reduced risk of a large fire would mean that it would be a win/win situation. Our local RFS brigades are all for it (admittedly some out of self interest) but every attempt they make to offer their services to NPWS to help burn sections of the local Park seem to be answered with excuses and problems. It doesn’t help that every few years there is a new person to try and deal with. If anyone knows of it being done, does it increase the health and biodiversity of the forest? Are there any downsides in the medium to long term? sheepman | |
| From: Dave | 01/05/2001 13:15:09 |
| Subject: re: Fire and the Australian Bush | post id: 3650 |
| boxhead, The flora of most of the Australian bush is very much reliant on fire, however a good understanding of the biology of the plants is needed. Some species survive fires to a certain intensity and use it to trigger new growth. However they need a number of years to build up the energy stores and short term sequential fires can kill these species. Some species are killed by fire of certain intensity but use it to trigger seed dispersal. However they may not reach flowering age for many years and short term sequential fires can kill these species. Alternatively low intensity fires may kill the species but not trigger seed dispersal. The seeds of some species are stored in the soil and require a certain intensity fire to trigger germination. If fires are consistently low intensity then the parent plant may die but germination may not be triggered. Pile burns are often used by bush regenerators to trigger germination from soil seed banks and kill weed seeds. There are also many fire intolerant ecosystems, particularly remnant rainforest patches and softwood species. This is why a lot of woodland areas are being altered through softwood invasions - fire has been ommitted. NPWS usually have a good handle on what has been burnt, where, when, at what intensity etc. Litter load reduction is not always on the agenda as an area of a park might be due for a high intensity burn as part of regeneration. High intensity fires also cause hollows and habitat areas. An example - Banksia serrata (Old Man Banksia) is killed by fire but uses it to trigger seed dispersal. It takes 15 years for a Banksia serrata to reach flowering age. A low intensity fire will kill Bansia serrata without triggering germination. Short term high intensity fires will cause localised extinction. | |
| From: boxhead® | 01/05/2001 13:31:48 |
| Subject: re: Fire and the Australian Bush | post id: 3656 |
| Thanks Dave, A lot to think about there :) The park we are concerned with is only a small one, a few thousand hectares and the only controled burn done in my lifetime has been along the highway, once. There was one major bushfire go through most of it in 1969 but other than that nothing, and AFAIK nothing is planned. My thoughts on the matter is that generaly a medium sized fire in part of a forest every 5 to 10 years, in rotation, is better than one huge on whenever a bushfire gets out of control (which is getting less frequent these days, IMO). sheepman | |
| From: Lib (Avatar) | 01/05/2001 13:53:20 |
| Subject: re: Fire and the Australian Bush | post id: 3660 |
| In NSW the parks service has fire plans for all their nat parks. The parks, or parts of are burnt in rotation at varying intensities to reduce fuel loads and provide the conditions necessary for many species to shed seed or for seeds to germinate. The RFS also produces prescription burn plans or SFAZs. Don't ask me what that stands for, but the plans are only usually prepared for the bush around residential areas. They don't worry about reducing fuel loads in areas where it is unlikely that a wildfire will impinge on property. My local RFS brigade helps the Nat Parks when requested to do so. Recently we conducted a hazard reduction requested by parks to encourage the flowering of a native orchid so that it's presence could be checked for. The land was not parks owned, but the species is a threatened one so parks initiated the burn under the Environmental Planning and Assessment Act to check for the presence of the species following a development proposal. Admittedly the RFS and Nat Parks tend not to work together as memebers of the RFS have different agendas, however, with careful planning it is possible. | |
| From: Dave | 01/05/2001 14:05:03 |
| Subject: re: Fire and the Australian Bush | post id: 3661 |
| I'll throw a few more things to think about. A small park is quite likely to be an island and any local extinctions would be permanent. There is no connected source for new stock to enter the park. Some Eucalypt species require near 40 years to reach flowering age. Fire provides barren soil and allows weed invasion and soil erosion. Weed invasion is easier at edges and a small park has a greater edge to area ratio. Thus any disturbance in a small park is potentially catastrophic. | |
| From: eric | 01/05/2001 19:57:34 |
| Subject: re: Fire and the Australian Bush | post id: 3671 |
| Dear boxhead, Is there any rainforest involved? I have been keenly observing the dynamics of fire in grassland and Eucalypt forest which tends to get invaded by rainforest species and wattles. Many areas in SE qld have reverted to rainforest. The desirability of this is open to debate, case by case, but locally it is mostly thought desirable to keep the rainforest back. For my area near Toowoomba Qld. (not to disagree with anyone else's contributions) : A fire tends to trigger germination of a lot of wattles, and the forest gets choked with wattles if there aren't enough follow up fires in the next few years. Particularly if the area has not been burnt for some time. Eucalypts sometimes also germinate. Wattles and Eucalypts survive fire or sucker readily once they are old enough. Here, the idea is to kill the wattles and keep the forest open with little understorey. It seems to be a long slog, perhaps even impossible, in an area which has been neglected after a fire 5 years before. Wattles sucker to almost the same height by the next year. 80-90 % survive a fire. Without successful burning, it gets to the point where the understorey has too little grass to carry a fire, except in an extreme drought. Which can be bad news. Once eucalypt seedlings develop a lignotuber (maybe at only 30 cm high), they usually regrow after burning. Ideally, burning should be done the way aboriginals used to do it. That has a good chance of maintaining the species originally there in the most stable ecosystem. But: What was the local aboriginal fire regime? and Has ecological change since then rendered this impractical? Not to mention Real Estate issues. It is a complex issue to take into account the biology of all the species involved. There is often no exact turning back of the clock. It's probably a matter of prioritising for certain species and against certain weeds. Your best chance of making any headway with NPWS may be after a wildfire! IDST | |
| From: eric | 01/05/2001 19:58:14 |
| Subject: re: Fire and the Australian Bush | post id: 3672 |
| IDST - I Didn't Say That | |
| From: boxhead® | 01/05/2001 20:34:09 |
| Subject: re: Fire and the Australian Bush | post id: 3675 |
| It's amazing what you can find around the place if you look :). I found this species list of the area in question. (Uses MS Word, hopefully it will work for you). A small park is quite likely to be an island and any local extinctions would be permanent. There is no connected source for new stock to enter the park. Although a lot of people are frantically trying to link it up, effectively it is. Wouldn't this mean that it is in greater danger of a large fire, for both the vegetation and the wildlife? BTW that fire was in 1979, not '69 :) sheepman | |
| From: boxhead® | 01/05/2001 20:39:51 |
| Subject: re: Fire and the Australian Bush | post id: 3676 |
| Meant to say no rainforest eric. I'm on the Southern Tablelands in NSW, if you can't work it out from that link :) sheepman | |
| From: Davidavid | 02/05/2001 7:47:47 |
| Subject: re: Fire and the Australian Bush | post id: 3707 |
| I remember when I was up on my cousins banana farm on the edge of the Eungella national park, near mackay, and there was one hill that had a distinct contrasting colour of vegetation: a much lighter green at the top than the bottom. It turns out that there's eucalypt at the top, then rainforest at the bottom. The old owner of the property used to burn back this hill a lot and all the rainforest would die, but the eucalypt would survive and advance a little way down the hill. Then when the rainforest came back it would gradually make up its lost ground. I seem to remember that there was one rainforest species alone that could survive the burning. It was a funny old hill that... Davidavid | |
| From: Dave | 02/05/2001 8:09:24 |
| Subject: re: Fire and the Australian Bush | post id: 3709 |
| Eric What you have described is regarded as the normal succession of woodlands after fire. The wattles grow back first, quite thick. The Eucalypts then grow up straight and tall through the wattles and start to grow them out. The wattles then die off (can't remember exact life expectancy but it is nowhere near the Eucalypts). This, grazing by native herbivores and fire keeps the ecosystem as a woodland. Humans speed up the process by introducing a more regular fire regime as they want to utilise the grass. They may also reduce the number of Eucalypts. No problem here as long as they let the occasional young tree come through for replacement. The main trigger for growth in the Darling Downs area is flood. Hence the suckers. It is also why tree clearing is so costly as one tree comes down and sends up 5-10 suckers to replace it. Boxhead Not sure re large fires in small island parks. I'll check with my colleague today and get back to you. | |
| From: acacia | 05/05/2001 20:09:36 |
| Subject: re: Fire and the Australian Bush | post id: 4054 |
| There was a good little book published by the ABC in 1993 that had the same title as your question. Its called Roger Oxley Looks at Australian Trees. Have a squizz at it. | |
| From: eric | 05/05/2001 20:25:49 |
| Subject: re: Fire and the Australian Bush | post id: 4056 |
| Reasonable idea. Here are some more books: Pyne, S.J. (1991). Burning Bush: A Fire History of Australia. Sydney : Allen & Unwin xix 520 pp. Gill, Groves & Noble Eds. 1981 Fire and the Australian Biota. Aust. Acad. Sci. Canberra. Bowman, David (1999?) Australian Rainforests: Islands of green in a land of fire. Cambridge University Press. $120. Groves, R.H. Ed.1981 Australian Vegetation. Cambr. Univ. Pr. | |
| From: eric | 05/05/2001 20:44:17 |
| Subject: re: Fire and the Australian Bush | post id: 4058 |
| The normal succession in montane parts of SE Qld. is: wattles ( which eventually exclude fire) - rainforest thickets - rainforest with emergent eucalypts. Fire very rarely destroys the mature eucalypts anywhere in Queensland, so there is not really a succession, just in the understorey, at first anyway. But eucalypts cannot germinate under the rainforest canopy, and eventually die out. So rainforest is actually the biotic climax here. Eucalypt is a disclamax community maintained by fire. Even rainforest species can sucker well after fire. It takes frequent fires to halt the succession. | |
| From: boxhead® | 27/12/2001 1:35:37 |
| Subject: re: Fire and the Australian Bush | post id: 25482 |
| Aboriginal fire management (an interesting site, mainly on NT fire management) | |
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