Land for Wildlife hosted a Fire Workshop back in May with a focus on Fire and the effects on wildlife, particularly arboreal mammals.
The subject is of course complex and controversial but vital to the management of our landscapes and the ecology of our native species.
To try a give a balanced perspective we organised a very well known fire ecologist Alan Andersen to present alongside Natalie Rossiter on the findings of fire experiments that have been conducted over several years in bushland at the Territory Wildlife Park and then for participants to be given an insight into the effect of fire on Wildlife and landscapes from a land manager’s point of view with Andrew Spiers giving a walk and talk, who also has many years of land management experience from National Parks and teaching and observing in the field. There are of course many other experts in fire and many studies and perspectives to consider.
Over 20 people attended the workshop, including fire volunteer and land managers. They were shown the fire plots at The Territory Wildlife Park and then invited for a walk and talk on Andrew Spier’s property on the nearby Blackmore River flood plain. Greg Miles also attended and offered his perspective from being a long term ranger and Land Manager in Kakadu as well as managing his own Land for Wildlife property.
Gamba grass is a huge factor in affecting the fire regime. (see below). Fire management or regime involves the factors of frequency, patch size and shape burnt and fuel load (related to time of year) and conditions (dew point, wind etc. also related to time of year)
- Savannah Landscapes have been shaped by fire over a very long time in Australia to be dominant in species with fire survival mechanisms that thrive with fire such as Eucalypts and grasses.
- Riverine areas, Monsoon forests and wet lands are more sensitive areas of vegetation and frequent fire does not allow them to regenerate as a Savannah landscape does. Often as these landscapes are bordered by woodland there can be a knock on or edge effect.
- Gamba grass is a considerable factor in adding to fuel load and curing only to burn later, when fire is hot and to intense for other native species to recover.
- The fire experiments have found that burns on the same area of bushland every 4 years (early or even later on) creates greater biodiversity (Andrew Andersen)
- The longer term ecological interactions of species is the important factor that fire effects rather than the immediate effect on wildlife (Andrew Andersen)
- Fire effects different species differently, there are some winners and some losers (Andrew Andersen)
- Generally when fire is absent the tree layer becomes more mature and dense and fire sensitive species start to colonise, the grass layer reduces.
- In the case of arboreal mammals, the absence of fire is favorable as mid-story fruiting plants, rainforest fruiting plants are more abundant as a food source and old growth trees stand for longer and harbour hollows.
- It is very difficult to manage fire on a large property as there are many “wild fires” which are uninvited. Many flowering plants are lost when this happens on the floodplains.
- It really is down to the land manager to decide how they shape the landscape they manage with (or without) fire
- Greg Miles introduced the idea of wet season burning, which we may invite LFW members to learn more about later in the year, below is a short summary:
by Greg Miles
Most land managers have adopted the advice of fire experts and been doing early dry season burning (EDS) for the protection of assets and to prevent destructive late season fires (LDS) later in the year. While there are very good reasons to use EDS for this purpose, I would argue that what suites asset protection may not suit the natural ecology. After 40 years of involvement in natural area fire management I have come to the view that EDS burning is cumulatively killing the woodlands of the Top End. There is a mountain of circumstantial evidence to support this hypothesis, but it is contradicted in part by some research findings, especially CSIRO’s Kapalga Fire Experiment of the 1980’s. But it is clear to me that frequent EDS burning promotes annual grasses, especially native speargrass. Burning encourages more grassy fuel which encourages hotter burning which encourages more grass – ad infinitum. Thus a “grass fire cycle” is created. This cycle is improving the hunting success of cats and is slowly killing the pre-European ecology of the woodlands. Add in Cane Toads and invasive African Grasses and you have the perfect storm. But there is a way to break the grass fuel cycle. In my view the solution is to reduce the amount of EDS burning and instead, dramatically increase the amount of early wet season burning (EWS). Sure there are many practical problems with doing this, but they can be managed. WSB is more intellectually demanding than EDS burning, but that should not be seen as a reason not to do it. My prediction is that if land managers were to switch from EDS to EWS burning they would see a rapid turn around in the ecological health of the natural woodlands landscape.