Lotsafreshair wrote: by Lotsafreshair » Thu 20 Jun, 2013 9:03 am
One question Clarence... Can the problem be solved with a Krav "thumb" move to simply bring it down?
Please explain? A "Krav thumb" sounds like a big wall climbing move to me.
Pteropus wrote:
clarence wrote:The timing of flowering and seed set in a given season is generallyonly partially relevant. What is more relevant is the time (for species which regenerate from seed only) taken to reach flowering and seed set.
Yes, as you say the frequency is very important for many plant species. The relevancy of timing of fire when plants are flowering is also important because it provides a food source for many species such as numerous bird species, mammals and of course, insects. Animals may survive the fire, but a paucity of food can follow, with potential negative effects on animal populations. Of course this can happen with any fire, but burn planning should consider secondary impacts of a fire on both flora and fauna.
I agree Pteropus. (I was referring firstly to vegetation, which is more my area of expertise). As I said, it is a very complex issue, and differs hugely for different animal species depending on mobility, feeding patterns, their reproductive cycle, where they live etc. (For example a bird can easily fly away, then fly back a few days or weeks later if it wants. A wallaby on the ground which can neither move faster than a fire front nor hide is a hole, is probably screwed.) At one extreme a patchy and cool fire will have minimal impact on many animal species, however the animals can potentially recolonise very quickly and this
may hinder the regeneration of certain plant species. At the other extreme a large hot broad-scale fire will totally wipe out certain species which will be forced to recolonoise from further afield. After a large complete burn, for example, a bird could fly a few km away and forage on flowers in unburnt bush. A cool patchy burn, as an alternative example, may indeed favour a wallaby which able to take advantage of the flush germination/resprouting after the fire. This is where the mix of season, intensity, patchiness, fire interval, presence of "refugia" (ie areas which are "safe" from fire, like wet rainforested gullies) etc all come in to play. As Gippsmick said, burning based solely on reaching hectares per annum targets is not fantastic unless it take into account a whole raft of issues (including whether the area is a genuine fire risk at all in the first place).
On that issue, I would argue that barriers to recolonisation for mammal species is a more significant issue than the area or season of the burn. Take, for example, the large scale fires in Royal NP in the last 30 years where nearly the whole park has been burnt. For mammals to recolonise from adjacent bushland (catchment areas, Heathcote NP) is a dicey affair with a railway and major freeway, suburbia etc blocking access. Hence, any residual populations (if there are any at all) on the east side of the freeway are far more likley to recolonise- making it possibly slower, but also meaning the whole park may be filled from a very limited genetic stock in the longer term- which is another story. Throw in a few cats and dogs in the unburnt bush on the urban fringe, where small mammals may preferentially feed, and it complicates regeneration further. In the case of the Wild Dog burns, this opposite is probably true as there is a huge perimeter from which mammal recolonisation can occur without impediment. It is all part of the mix that must go in to fire planning.
I recall a huge fire in the Blue Breaks in about 1995, and another on the tablelands around Belloon Pass in the late 1990s. Both of these were probably a few thousand hectares- not too different to the recent Wild Dog burn. When an unplanned burn occurs, in come the the helicopters with fire retardant, bulldozers, fire tankers, back burn lines etc etc. The newly made bare earth "control lines" create entry points for feral animals, weeds, greater erosion, trailbikes etc etc. One could argue that a controlled and planned burn like the Wild Dogs is no more destructive than these unplanned burns and the human impact of trying to manage them in a similar landscape
What is also worth noting, and which has not been stated, is that an interval between fire which is "too long" can also have negative consequences from a conservation perspective, as certain species will also decline (in either absolute or relative measures) over time. This goes for both plants and animals.
It is also worth noting that over time fuel loads do NOT continue to increase at the same rate, and eventaully more or less plateau out. The natural breakdown by rotting, termites, microorganisms etc allows a more or less steady state to be acheived in the longer term.
AS I stated, it is a very complex and fascinating topic and if you are generally interested I would refer you to the book by Whelan. (It is a good mix of readability and science by a world leader in the field.) Reading such material can give a typcial outdoors person a much better understanding of the way our landscape works. Having an understanding of our natural environment and how it works is a good thing and can make one appreciate and view the bush in a different way.
Clarence
