Fire and introduced species

[phsculpture]

Does anyone know if once a bushfire moves through, are the introduced flora much less likely (or not at all) to be able to regenerate? I'm guessing so, unless they were introduced from a similar climate prone to fire, but it would be interesting to hear if anyone has data or experience.

[maddog]

The answer depends on the circumstances. If the fire is suitably frequent and of the intense, it may well suit the natives. If the fire is too severe, frequent or infrequent, occurs at the wrong time of year, or within the wrong community (e.g. rainforest), it will cause the decline of the native, allowing the infiltration of highly competitive exotic weed species into previously intact stands of native vegetation, like any other form of land clearing.

Native animals are largely responsible for the spread of exotic weeds in such circumstances, especially birds (but also bats, gliders, rats, etc.), deprived of their usual food so turning to exotic sources and facilitating the spread of weeds species (e.g. Camphor seed consumed and distributed by native birds). Intense fire can also ruin previously pleasant landscapes, allowing Invasive Native Species to take hold after disturbance and the significant thickening of woody vegetation (e.g. closed wattle forest replacing grassland or woodland communities). It is also worth noting that Camphor laurel, Willow, and Celtus species, all invasive (noxious) weeds in NSW, were amongst those to survive the bomb in Hiroshima:

http://www.unitar.org/hiroshima/sites/u ... 2011_1.pdf

[icefest]

The answer depends on the circumstances. If the fire is suitably frequent and of the intense, it may well suit the natives. If the fire is too severe, frequent or infrequent, occurs at the wrong time of year, or within the wrong community (e.g. rainforest), it will cause the decline of the native, allowing the infiltration of highly competitive exotic weed species into previously intact stands of native vegetation, like any other form of land clearing.

Native animals are largely responsible for the spread of exotic weeds in such circumstances, especially birds (but also bats, gliders, rats, etc.), deprived of their usual food so turning to exotic sources and facilitating the spread of weeds species (e.g. Camphor seed consumed and distributed by native birds). Intense fire can also ruin previously pleasant landscapes, allowing Invasive Native Species to take hold after disturbance and the significant thickening of woody vegetation (e.g. closed wattle forest replacing grassland or woodland communities). It is also worth noting that Camphor laurel, Willow, and Celtus species, all invasive (noxious) weeds in NSW, were amongst those to survive the bomb in Hiroshima:

http://www.unitar.org/hiroshima/sites/u ... 2011_1.pdf

A eucalyptus survived too: Eucalyptus melliodora

[pazzar]

This is an interesting one. Fire is a great promoter of biodiversity, but as maddog has said, in the wrong condition it can be great for the invasive species, and it can be damaging if the fire is too intense. You only need to look at some of the scarring from the Kinglake fires in 2009. Many of the trees burnt in that fire have not recovered because the fire was too intense. Many species of Eucalyptus are serotinous, meaning that they require heat to germinate their seeds, so fire is an essential part of the survival of the species.

I've been researching lots on grassland management (I'm supposed to be writing an essay on it now!), and in many cases if a grassland doesn't receive regular, low-intensity burns, it is more susceptible to invasion due to swards being suffocated by dead litter and the space in between tussocks decreasing.

If you want some names of people to read, Lunt, Morgan, and Kirkpatrick are leading grass guys in Australia, or for fire, there are heaps out there, Marsden-Smedley is the leading guy in Tassie, but he does work all over the place. It is a very interesting subject area.