Hi Jeremy,
The paper deals with plant communities in south-eastern, as well as
south-western Australia. I accept your point that these two regions are
not the "vast majority" of Australia, but I dispute your claim that these
regions have "narrow specific ecosystems". Nor was the paper referring to
narrow specific ecosystems. If you have the opportunity to read the paper
it refers to a wide range of plant communities (and species within them),
from heathlands, to dry open woodland and wet and dry forests, just to name
a few. The reason I decided to respond to your earlier comment is that you
said that eucalypt forests are especially adapted to regular fire regimes.
Although eucalypt species can be found across most of Australia, many
eucalypt forest communities are found within south-eastern and south-western
Australia. The point that was raised in the paper is that what we have
identified as adaptations to fire may in fact be exaptations (traits that
have evolved for some other purpose, but which coincidentally assist plant
species to survive bushfires) rather than traits that have specifically
evolved to assist plant species to survive regular bushfires (i.e.
adaptations).
I'm not saying that the authors of the paper are right or wrong. I'm merely
pointing out that there are alternative points of view out there.
Kind regards,
Stephen
Stephen Ambrose
Ryde NSW
From: On Behalf Of Jeremy O'Wheel
Sent: Thursday, 5 September 2013 4:07 PM
To: Stephen Ambrose
Cc: Roger Giller; Frank O'Connor; birding-aus
Subject: the fire hazzard reduction program
I don't think anybody doubts the complexity of specific relationships
between fire and ecosystems, especially when you're talking about narrow
specific ecosystems such as that paper. As I said too much and not enough
fire are both problems. Last time I checked, South West WA does not make up
the "vast majority" of Australia, and "vast majority" does not mean all.
Jeremy
On 5 September 2013 15:57, Stephen Ambrose <> wrote:
> The vast majority of Australia's bush is adapted to regular fire regimes -
especially Eucalyptus forests, inland mallee and grassland.
The following review paper written by eminent biologists from the University
of WA and Kings Park & Botanic Garden in Perth provides the contrary view
for native vegetation that occurs in south-western and south-eastern
Australia:
Bradshaw, SD, Dixon, KW, Hopper, SD, Lambers, H., & Turner, SR (2011).
Little evidence for fire-adapted plant trails in Mediterranean climate
regions. Trends in Plant Science 16: 69-76
The paper was written out of the authors' concerns of the ecological impacts
of the extensive control-burning that occurs in south-western Australia,
similar to those concerns already expressed by Frank O'Connor here on
Birding-aus.
Abstract
As climate change increases vegetation combustibility,
humans are impacted by wildfires through loss of lives
and property, leading to an increased emphasis on prescribed
burning practices to reduce hazards. A key and
pervading concept accepted by most environmental
managers is that combustible ecosystems have traditionally
burnt because plants are fire adapted. In this
opinion article, we explore the concept of plant traits
adapted to fire in Mediterranean climates. In the light of
major threats to biodiversity conservation, we recommend
caution in deliberately increasing fire frequencies
if ecosystem degradation and plant extinctions are to be
averted as a result of the practice.
The Paper's Conclusion
Our review of the literature suggests that traits commonly
accepted as 'fire adaptations' of Mediterranean-climate
plants have more complex origins and that environmental
factors other than frequent fire have promoted their evolution
[97]. Traits such as resprouting, serotiny, physical
dormancy, facultative post-fire flowering and smoke-induced
germination can all enhance survivorship and fitness
under certain fire regimes, but these should be considered as
exaptations rather than adaptations (Table 1). This selective
advantage is readily negated, however, in plant communities
in which fires occur with a frequency higher than
the time taken to flower and set seed for the slowest-maturing
species in that community. The impact of fires on
communities is also a function of their intensity and the
season in which they occur, both of which can override any
inherent advantages flowing from morphological and physiological
exaptations. Climate change, with increasing temperatures
and declining rainfall predicted in Mediterranean
biomes in the coming decades, is likely to exacerbate the
current loss of biodiversity in these regions and will present
a major challenge for environmental managers also charged
with protecting human life and property [98]. We question
the widespread assumption that Mediterranean-ecosystem species
are adapted to fire and suggest that caution is
required in the use of frequent prescribed burning if ecosystem
degradation and plant extinctions are to be averted as a
result of the practice.
Kind regards,
Stephen
Dr Stephen Ambrose
Ryde NSW
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