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Fire regimes and Biodiversity in Victoria’s alpine ecosystems.

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Landscape-scale fires occur in Australian alpine ecosystems once or twice per century, primarily when ignition, regional drought and severe fire weather coincide. When alpine vegetation does burn, there is con- siderable variation in landscape flammability and fire severity. Regeneration following extensive fires of 2003 and 2006-07 across the Bogong High Plains is occurring in all plant communities (heathlands, grass- lands, herbfields and wetlands). In heathland and grassland, vegetation composition has converged towards the long-unburnt state (> 50 years) eight years post fire. There was little effect of variation in fire severity on patterns of regeneration in heathland. In burnt wetlands, Sphagnum cristatum and other dominant spe- cies are regenerating; the cover of obligate seeding ericaceous shrubs two years post-fire was positively re- lated to the cover of Sphagnum. The endangered mammal Burramys parvus is also capable of persisting in the alpine landscape after individual large, landscape fires. We conclude that there is no scientific evidence that these fires necessarily had ‘disastrous’ biodiversity consequences. After extensive landscape fires, the primary management objective should be to allow burnt alpine ecosystems to regenerate with minimal subsequent disturbance. Monitoring ecological change in the coming century will be essential for effective management of both fire and biodiversity in alpine ecosystems in Victoria and elsewhere in Australia.
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VOLUME124 NUMBER1 30JUNE2012
©TheRoyalSocietyofVictoriaIncorporated,2012 ISSN00359211
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PROCEEDINGS
AND
TRANSACTIONS
OF
THE ROYAL SOCIETY OF VICTORIA
Volume 124
NUMBER 1
PROCEEDINGS OF THE SYMPOSIUM
ON
FIRE AND BIODIVERSITY IN VICTORIA
held by the Victorian National Park Association
and
the Royal Society of Victoria
on 24-25 October 2011
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© The Royal Society of Victoria Incorporated, 2010
ISSN 0035-9211
101
AUSTRALIAN alpine ecosystems are subject
to recurrent fire. Alpine vegetation (hereafter we
include the treeless vegetation above treeline, and
floristically similar treeless vegetation at or below
treeline in the high subalpine zone, in our definition
of ‘alpine’; Williams et al. 2006a) typically burns at
landscape scales once or twice per century, under
circumstances when ignition and severe fire weather
coincide with widespread regional drought. Under
these conditions, fire spreads to the treeless, alpine
and subalpine vegetation via the foothill and montane
forests and subalpine woodlands (Williams et al.
2008). Such fires occurred in the alpine regions of
Victoria and New South Wales in 2003 and 2006-07.
The 2003 fires burnt over 1 million hectares, the vast
majority being forests and woodlands. About 10,000
ha of treeless, alpine vegetation was burnt, including
about half of the Bogong High Plains (Williams et
al. 2006b). The fires of 2003 and 2006-07 in north-
eastern Victoria were the largest since 1939, when
much of the Victorian Alps burnt (Carr and Turner
1959). There have been other substantial fires in
Victoria’s treeless sub-alpine vegetation since 1939,
such as on Wellington and Holmes Plains in 1998
(Wahren et al. 2001), and on Mt Buffalo, parts of
which were burnt in 1972, 1984, 2003 and 2006-07
(Coates and Walsh 2010).
Much of the alpine and treeless subalpine vegetation
burnt by the large fires of 1998, 2003 and 2006-07
occurred in national parks within the Victorian Alps.
Well-informed fire management within national
parks is essential to achieve nature conservation
goals, but is controversial, with competing views
concerning the ecology and management of large
fires in south-eastern Australia. One view (e.g. House
of Representatives 2003; Adams and Attiwill 2011)
is that (a) fires such as those that occurred in 2003
were unnatural, and are (b) the resulted of inadequate
fuel management in the surrounding forests, and are
(c) a major threat to biodiversity and other natural
FIRE REGIMES AND BIODIVERSITY IN
VICTORIA’S ALPINE ECOSYSTEMS
R
ICHARD J WILLIAMS
1
, CARL-HENRIK WAHREN
2
, JAMES M
SHANNON
3
, WARWICK A PAPST
2
, DEAN A HEINZE
4
, JAMES S CAMAC
2,5
1 CSIRO Ecosystem Sciences, PMB 44 Winnellie 0822 NT Australia
2 Research Centre for Applied Alpine Ecology, Department of Agricultural
Sciences, La Trobe University, Victoria 3086 Australia
3 Research Centre for Applied Alpine Ecology, Department of Botany,
La Trobe University, Victoria 3086 Australia
4 Department of Environmental Management and Ecology, La Trobe University, Wodonga Victoria
3689, Australia
5 Centre of Excellence for Environmental Decisions, School of Botany,
The University of Melbourne, Victoria 3010, Australia
WILLIAMS, R.J., WAHREN, C.H., SHANNON, J.M., PAPST, W.A., HEINZE, D.A. & CAMAC, J.S. 2012. Fire re-
gimes and biodiversity in Victoria’s alpine ecosystems. Proceedings of the Royal Society of Victoria,
124(1): 101-109. ISSN 0035-9211.
Landscape-scale fires occur in Australian alpine ecosystems once or twice per century, primarily when
ignition, regional drought and severe fire weather coincide. When alpine vegetation does burn, there is con-
siderable variation in landscape flammability and fire severity. Regeneration following extensive fires of
2003 and 2006-07 across the Bogong High Plains is occurring in all plant communities (heathlands, grass-
lands, herbfields and wetlands). In heathland and grassland, vegetation composition has converged towards
the long-unburnt state (> 50 years) eight years post fire. There was little effect of variation in fire severity
on patterns of regeneration in heathland. In burnt wetlands, Sphagnum cristatum and other dominant spe-
cies are regenerating; the cover of obligate seeding ericaceous shrubs two years post-fire was positively re-
lated to the cover of Sphagnum. The endangered mammal Burramys parvus is also capable of persisting in
the alpine landscape after individual large, landscape fires. We conclude that there is no scientific evidence
that these fires necessarily had ‘disastrous’ biodiversity consequences. After extensive landscape fires, the
primary management objective should be to allow burnt alpine ecosystems to regenerate with minimal
subsequent disturbance. Monitoring ecological change in the coming century will be essential for effective
management of both fire and biodiversity in alpine ecosystems in Victoria and elsewhere in Australia.
Key words: alpine vegetation, grassland, heathland, fire severity, species diversity, conservation.
102
values within national parks, because of their size
and intensity. On the other hand, there is evidence
that large, intense fires are a natural part of the
historical fire regimes of the temperate landscapes of
south-eastern Australia, and the associated biota are
resilient to individual large, intense fires (Bradstock
2008). According to this view, large individual fires,
because they are a part of the historical fire regime,
may not necessarily threaten conservation values in
these landscapes. Evidence from the alpine and high
subalpine ecosystems of SE Australia suggests that
large fires, such as the 2003 fires, are part of the
historical alpine fire regime (Williams et al. 2006b;
2008). Furthermore, regeneration following such
fires, across a broad suite of taxonomic groups, can
be both rapid and substantial (Wahren et al. 2001;
Walsh and McDougall 2005; Williams et al. 2008;
Camac et al. 2012).
Driscoll et al. (2010) highlighted key questions in
relation to fire regimes (sensu Gill 1975) and their
management for biodiversity conservation. They
stressed the importance of natural experiments
(e.g. studying major fires), studying species-level
responses to variation in fundamental fire regime
components (e.g. time since fire, intervals between
fires, fire intensity) and the value of long-term
monitoring. Victoria’s alpine areas thus present a
valuable opportunity to further this understanding,
because (a) variation in occurrence and severity
of fire across a diverse array of plant communities
provides a robust natural experiment, (b) knowledge
about species-responses to time since fire and fire
severity is increasing and (c) the alpine vegetation
of Victoria has been monitored systematically since
the 1980s.
In this paper we explore the effects of recent,
extensive fires on the major treeless plant
communities (grasslands, heathlands and wetlands)
from the alpine zone and high subalpine zone in the
Victorian Alps. We draw on long-term monitoring
data to make inferences about the effects of large
fires on variation over time in key ecological
attributes such as vegetation cover, species diversity
and populations of species. We also present data on
the ecological effects of variation in fire severity
(a proxy for fire intensity; Keeley 2009). We also
present data on post-fire recovery of an endangered
small mammal, the alpine endemic Mountain Pygmy-
possum (Burramys parvus).
DATA SOURCES, SELECTION AND
ANALYSES
Victoria’s alpine and treeless subalpine vegetation
is a mosaic of shrub- and grass/herb-dominated
communities. The major structural formations are
closed- and open heathlands, herbfields, tussock
grasslands and wetlands. We present data from
monitoring sites in closed heathland, open heathland,
grassland and wetlands, which collectively account
for >95% of the treeless vegetation in alpine and
high subalpine landscapes. Detailed community
descriptions are found in Williams et al. (2006b).
We use data from long-term, permanent monitoring
sites established over the past 25 years across the
Victorian alpine region (Papst et al. 1999). ‘Burnt’
monitoring sites were established within 2-4 weeks
at sites affected by the fires of 1998, 2003 and/or
2006-07. Some ‘unburnt’ sites were established at the
time of these extensive fires; others were established
in the 1970s, 1980s and 1990s, as part of a wider
as part of a wider program of long-term ecological
monitoring. We present vegetation data from the
2003 and 2007 fires on the Bogong High Plains and
the 2007 fires on Bennison-Moroka-Snowy Range.
Sites were monitored at ca. 1-5 year intervals. For
the purposes of this paper ‘unburnt’ refers to sites
that were not burnt by any of these fires, and which
have been unburnt since at least 1939. The data on
Burramys parvus come from population monitoring
sites across the Bogong High Plains-Mt Hotham
region (Heinze 2010) established in the 1990s.
Logistical constraints precluded assessment of all
sites in all years. Nevertheless, our data are from a
representative subset of monitoring sites from which
we can derive robust measures of pre-fire state for a
range of taxa, and change in state in those variables
from immediately after the fire until 8 years post-
fire.
Plant community data from heathlands and
grasslands were collected from 11 monitoring sites,
based on point quadrats along multiple (usually 10)
10m-long transects per site. Attributes collected
include cover of vascular plant species, species
diversity and composition, and the amount of bare
ground (Wahren et al. 1994; 2001). Following the
2003 fires on the Bogong High Plains, fire severity
in open and closed heathland was determined using
‘minimum twig diameter’, a proxy measure for fire
severity (Williams et al. 2006b). In 2008, cover of
vascular plant species, species diversity (measured
as both richness and evenness; Jost et al. 2010) and
FIRE REGIMES AND BIODIVERSITY IN VICTORIA’S ALPINE ECOSYSTEMS
103
species composition were assessed using five 6 m2
plots along a 50 m transect at each of 40 sites (10
unburnt, 30 burnt to varying severity) per community;
cover was estimated using standard Braun Blanquet
methods (Camac et al. 2012). Data on wetlands
were collected from 17 sites, based on contiguous
0.25m
2
quadrats along permanent 30m transects in
each wetland. Primary attributes were the cover of
dominant taxa: Sphagnum cristatum, ericaceous and
myrtaceous shrubs, forbs and graminoids (Shannon
2012). Data on
Burramys were based on ‘capture-
mark-recapture’ protocols detailed in Heinze (2010).
These techniques detect changes in populations
over time, and determine survival, mortality and the
structure of local populations, for males and females.
Statistical analyses were based on 95% confidence
intervals, where the transect or trapping grid was the
experimental unit. Where 95% confidence intervals
of sample means did not overlap we inferred a
significant difference (Cumming and Finch 2005).
RESULTS
Post-fire regeneration in heathland and grassland
The cover of the dominant life forms (shrubs,
graminoids and forbs) and the amount of bare ground
in heathland and grassland following the 2003 fires
Fig. 1. Change in cover of major variables (graminoids, shrub, forbs, bare ground; mean + 95% CIs) in heathland (a, b) and
grassland (c, d) on the Bogong High Plains following the 2003 fires. Data are for burnt (a,c) and unburnt (b,d) sample sites.
Cover data collected from point quadrats along permanent transects according to methods in Wahren et al. (1994; 2001).
RICHARD J. WILLIAMS ET AL.
104
on the Bogong High are shown in Fig. 1. In heathland,
regeneration commenced within days of burning. The
cover of graminoids (mainly snowgrass, Poa spp) and
forbs increased relative to that of the unburnt sites,
especially in the initial 2-3 years post-fire. By 2011,
shrub cover was about 60% of its pre-fire level of ca.
85-95%. Despite fire causing substantial increases in
the amount of bare ground (from <5% to >80%), bare
ground was about 10% by 2011 (Figs 1a,b).
In grassland (Fig. 2 c,d), post-fire regeneration
was rapid for the snow grasses and forbs; the cover
of snowgrass had returned to pre-fire levels of cover
(ca. 90%) within 5 years. On unburnt sites, the cover
of snowgrass declined between 205 and 2011, as a
consequence of drought – the driest period on record
in south-eastern Australia (CSIRO, 2010; Timbal,
2009; Ummenhofer, 2009). Bare ground was initially
40-60% in the first two years post fire on burnt sites,
declining to ca. 20% in 2011. On unburnt sites, the
cover of bare ground was ca. 5-10% over most of
the monitoring period, increasing to 15% post-2005,
as a consequence of the drought-induced decline in
the cover of snowgrass. Although there were some
significant differences between burnt and unburnt
Fig. 2. Plant species diversity (mean + 95% CIs) as a function of time since the 2003 fires in grassland (a,b) and as a function
of fire severity in heathland (c, closed heathland; d, open heathland) five years after the 2003 fires. Diversity measures in
(a,b) are plant species richness (‘Richness’) and two measures of evenness (D1, D2; see Jost et al. 2010) per 10m transect.
Data from Bogong High Plains. (Note that x-axis of both (a) and (b) represents time since the 2003 fires). In Fig 2c,d fire
severity classes (unburnt, low severity, moderate severity and high severity) were measured in permanent reference sites in
2003-04 (Williams et al. 2006a) and diversity (plant species richness per 50 m transect) was recorded in December 2007
- January 2008 (Fig. 2c, d redrawn from data in Camac et al. 2012).
FIRE REGIMES AND BIODIVERSITY IN VICTORIA’S ALPINE ECOSYSTEMS
105
that in unburnt grasslands over the monitoring period.
Average total species richness per transect in burnt
grassland two months post-fire was ca. 20, increasing
to ca. 30 in 2010, compared with ca. 30 in unburnt
grassland over the same period (Fig 2 a,b). There
was no effect of variation in fire severity on plant
diversity in heathlands on the Bogong High Plains
(Fig. 2 c,d). Ordination of the sites over time also
demonstrated convergence in floristic composition of
burnt grassland and heathland towards the respective
unburnt state within 3-5 years (Camac et al. 2012).
Post-fire regeneration in wetlands
The average cover of the major wetland species
in 2006 (pooling sites) prior to the fires of 2006-
07, and in 2007 and 2009 is given in Table 1.
Sites are divided into ‘bog’ sites, where the pre-
fire cover of the dominant mound-building moss,
Sphagnum cristatum, is relatively high (>60%) and
‘wet heathland’ sites, where the pre-fire cover of S.
cristatum is relatively low (<25%) but other typical
wetland species, especially myrtaceous shrubs, are
common. Both vegetation types are underlain by peat
soils. Several post-fire responses are apparent. First,
Sphagnum can regenerate post-fire; Sphagnum had
reached ca. 80% and 70% of its pre-fire cover in bogs
and wet heaths respectively. Second, the cover of the
dominant graminoids, Empodisma minus and Carex
spp., may increase in the short-term, post-fire. Third,
the major ericaceous shrubs, Richea continentis
and Epacris spp. and the major myrtaceous
shrub Baeckea gunniana, were also regenerating.
Importantly, regeneration of the ericaceous shrubs,
which are obligate seeders, was substantially higher
in the bogs, where the cover of Sphagnum is higher,
than in the wet heaths. The cover of ericaceous
shrubs pre-fire was similar in both bog and wet heath
sites (ca. 33%) but was ca. 25% in the bogs in 2009,
compared with ca. 7% in the wet heaths.
Post-fire rends in Burramys parvus populations
Burramys persisted in areas that were burnt in the
2003 fires at both Mt Loch and Mt Higginbotham,
despite substantial population fluctuations (Fig.
3a,b). The situation was similar at other long-term
monitoring sites such as Timms Lookout. However,
the situation at Mt McKay was different (Fig. 3c).
Following the 2003 fires, there was limited recovery
vegetation in the cover of some life forms in some
years, after eight years the cover of shrubs, grasses
and forbs in burnt grassland was similar to that of
unburnt grassland. Bare ground, however, was
significantly higher at burnt sites than unburnt sites,
8 years post-fire.
Plant diversity in burnt grasslands (both richness
and evenness) was not significantly different from
Fig. 3. Trends in the numbers of Burramys parvus males
and females at three sites in Victoria, 1999/2000-2009.
Adult female population (soild line) and ‘known to be alive’
male population. (a) Mt Loch; (b) Mt Highinbotham East
and West (c) Mt McKay. (Source: Heinze 2010).
RICHARD J. WILLIAMS ET AL.
106
evidence that any species failed to regenerate after
fire. Our data are consistent with other studies of post-
fire regeneration of alpine heathland and grassland
on mainland Australia (Wahren et al. 2001; Walsh
and McDougall 2005; Williams et al. 2008).
The data from wetlands indicate clearly the
capacity of Sphagnum cristatum and other dominant
species to regenerate post-fire, despite some
wetlands having been moderately-severely burnt and
that Sphagnum is relatively slow growing (Shannon
2012). Whether post-fire regeneration in
Sphagnum
is from shoots that have survived at or near the
surface of the peat column, or from deeper-seated
shoots, is unclear. However, Sphagnum spp in the
UK can regenerate from decaying material 30 cm
below the surface of the peat (Clymo and Duckert
1986). Sphagnum is an important mound-building
species in Australian alpine wetlands (Williams
et al. 2006a; Shannon 2012) and other species of
Sphagnum are well-known as a mound-builders in
the northern hemisphere (Clymo and Hayward 1982).
Our data also highlight the importance of Sphagnum
as an ecological engineer (sensu Jones et al. 1994)
in Australian alpine environments – the cover of
obligate seeding ericaceous shrubs two years post-
fire was significantly higher in bogs, with a relatively
high cover of Sphagnum, than in wet heaths with
relatively low Sphagnum cover.
Burramys parvus
Burramys parvus is a small, rare mammal that
only occurs in restricted habitat in the Australian
Alps (Mansergh and Broom 1994). On this basis, it
may be expected to be highly vulnerable across its
range to large severe fires. However, monitoring of
Burramys populations before and after the 2003 and
of the numbers of both males and females. The
rate of recovery at Mt McKay was slower than at
other sites such as Mt Loch and Mt Higginbotham,
because the habitat at the McKay site is poorer than
that at the other sites (closed heath with no nearby
boulderfields; Heinze 2010). At Mt McKay the
population was further affected by fires in 2007,
which burnt heathland habitat that was also burnt in
2003. No animals were recorded at the McKay site in
2008 and 2009.
DISCUSSION
Vegetation
Alpine vegetation in Victoria has a strong capacity
to regenerate after fire, including high severity
fire. Our data show that there is clear evidence of
convergence in floristic composition, diversity and
some measures of ecosystem structure towards
the long unburnt state (i.e. unburnt for > 50 years)
within 5-10 years. This is especially apparent in
the grasslands and heathlands, but may also occur
in wetlands, especially where pre-fire cover of
Sphagnum is high (>50%). This rapid recovery
of diversity and composition occurs because most
species of the alpine vascular flora can resprout from
subterranean organs such as rhizomes, rootstocks
and tubers, with many species also able to regenerate
by seed (Williams et al. 2006a). Regeneration of the
dominant life forms in heathland appears to be largely
unaffected by variation in fire severity (Camac et al.
2012). Although diversity and composition show
convergence to the unburnt state in 5-8 years in
grasslands and heathlands, bare ground and shrub
cover are likely to take more than a decade to return
to unburnt/pre-fire levels. Importantly, we found no
Species Bog Wet heath
2006 2007 2009 2006 2007 2009
Sphagnum cristatum
62.8 (± 9.0) 42.1 (± 6.6) 51.4 (± 5.7) 23.3 (± 5.0) 7.9 (± 3.0) 15.5 (± 4.1)
Empodisma minus
17.3 (± 7.1)
6.3 (± 2.3) 22.9 (± 8.7) 12.4 (± 5.1) 0.8 (± 0.2) 9.2 (± 2.8)
Carex gaudichaudiana
0.8 (± 0.1) 1.4 (± 0.3)
2.7 (± 0.3) 2.9 (± 1.9) 3.8 (± 1.7) 7.2 (± 3.4)
Baeckea gunniana
9.6 (± 2.8) 2.9 (± 1.8) 5.4 (± 1.7) 12.3 (± 2.0) 1.5 (± 0.3) 5.9 (± 1.7)
Epacris spp.
18.0 (± 3.0)
8.0 (± 3.9) 15.7 (± 6.2) 12.8 (± 2.4) 1.1 (± 0.4) 4.4 (± 0.8)
Richea continentis
15.4 (± 8.5)
5.9 (± 4.2) 8.6 (± 5.2) 20.9 (± 9.7) 2.1 (± 1.6) 2.9 (± 1.9)
Table 1. Mean (+/- SD) cover values of six dominant and/or common taxa in the subalpine wetlands of the Bennison-
Moroka-Snowy Range region of Victoria. The wetlands were burnt in January 2007. Data were collected in April 2006;
April 2007 (3 months post-fire) and April 2009. (Source: Shannon 2012).
FIRE REGIMES AND BIODIVERSITY IN VICTORIA’S ALPINE ECOSYSTEMS
107
2006 bushfires on the Bogong High Plains has shown
that populations can persist in the landscape despite
widespread fire. This is potentially because its core
habitat (boulder fields) offers refuge from fire, and
a major food source over summer, the Bogong Moth
(Agrotis infusa), is migratory, aestivates among
rocks in large numbers over summer, and is thus
essentially independent of fire in the alpine zone.
Moreover, because the fires on the Bogong High
Plains in 2003 and 2006 were patchy (Williams et al.
2006b) unburnt patches of heathland could also have
served as refugia. Nevertheless, numbers plummeted
at Mt McKay after both the 2003 fires and 2006 fires
extensively burnt habitat, such that no Burramys
were trapped in 2009. The habitat at Mt McKay
was heathland as opposed to boulderfields, hence
it is not surprising that the loss of this vegetation
cover coincided with a dramatic decline in Burramys
numbers at this site. The Burramys population at
Mt McKay may now be functionally extinct. Thus,
although Burramys can persist post fire, it is at risk
from subsequent disturbances (e.g two fires < 5 years
apart in closed heathlands). It is also at risk, post-fire,
from predation by foxes, and drought (Green and
Sanecki 2006).
Management implications
The primary management implication of our
findings is that the alpine and high subalpine treeless
vegetation of Victoria is resilient to the effects of
occasional, large scale fires. This is clearly the
case with respect to plant species composition
and diversity in grasslands and heathlands, which
together account for about 90% of the area of treeless
vegetation. Importantly, our data also show that
species that may be hypothesised to be vulnerable
to large, severe fires – slow-growing plants such
as Sphagnum cristatum, and rare and endangered
mammals, such as Burramys parvus - can persist in
the landscape following such fires. Although large
fires undoubtedly have widespread and immediate
effects on alpine landscapes, and may result in
dramatic reductions in vegetation cover and faunal
population numbers, we found no evidence, across a
range of taxa, that the large, severe fires we studied
were of themselves ‘ecologically disastrous’. Indeed,
other ecological evidence suggests that this is the
case for the fire regimes and associated biota of the
widespread forests in the lowlands of south-eastern
Australia in general (Bradstock 2008).
One major management concern in burnt grasslands
and heathlands is the level of bare ground, which
remained well above unburnt/pre-fire levels even
8 years post-fire. Minimising the amount of bare
ground in alpine ecosystems is a primary objective
for soil, water and nature conservation (Williams
et al. 2006a). Thus, alpine vegetation that has been
burnt needs to be protected from other, subsequent
disturbances (prescribed fire, trampling, grazing
by domestic livestock and feral animals; weed
invasion) while it is regenerating, so that the rate of
development of native vegetation cover over bare
ground is maximised. Effective control of predators
and exotic plants in the post-fire environment is very
important. Although exhibiting broad resilience
to large fires, Burramys is vulnerable to predation
by foxes in the post-fire environment (Green and
Sanecki 2006).
Management of fire regimes in alpine ecosystems
also depends on effective long-term monitoring. We
are able to make inferences about the nature and
ecological effects of the recent large fires because
of the array of monitoring sites first established in
the 1940s. While grassland, heathland and even
wetlands appear resilient to the effects of one-off
large fires, and that regeneration in heathlands is
independent of fire severity, we know little about
ecosystem resilience in relation to intervals between
fires. Parts of the Mt Buffalo Plateau (e.g. Five Acre
Plain) have been burnt four times in the past four
decades. Evidence from such sites indicates that
short intervals between fires (<20 years) are likely
to have detrimental effects on a range of species and
ecosystem functions in alpine ecosystems (Coates
and Walsh 2010). Monitoring of areas burnt in 2003
and 2006-07 that may be burnt again in the next 5-20
years will therefore provide important information on
the responses of alpine ecosystems to variation in the
intervals between fires, which will complement our
developing understanding of how alpine ecosystems
are affected by variation in fire intensity/severity.
Change in the biota in of the Australian Alps will
be influenced by many factors, such as warming
climate, changing fire regimes (Williams et al. 2009),
a greater abundance of alien species (McDougall et
al. 2005) and increasing human pressure. Burgman
et al. (2007) have termed these interacting forces
‘threat syndromes’. It is these that are likely to
emerge as the main threats to biodiversity and the
capacity of protected areas to conserve biodiversity.
Because such threats interact at different spatial and
RICHARD J. WILLIAMS ET AL.
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ACKNOWLEDGEMENTS
We thank the Australian Research Council (Linkage
Grant Number: LP0883287) and the CSIRO Climate
Adaptation Flagship for financial and other support.
We thank Monica Brodzik, Roberta Campbell, Brad
Farmilo, Sam Grover, Karen Kapteinis, Hector
Proctor, Jack Reilly, Arn Tolsma, Paul Smart, Dr
Zachary Smith and Elaine Thomas for assistance in
the field.
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RICHARD J. WILLIAMS ET AL.
... The low percentage of species that we found resprouting supports the findings of Reference [72] that Tasmanian montane flora recovers very slowly, and appears less resilient to infrequent severe fire than mainland Australian montane flora. The low rate of resprouting, together with the patchy seedling regeneration observed, indicates that recovery of this shrubland will likely take a lot longer than the 8 years postulated by Reference [73] for recovery of the alpine Bogong High Plains in Victoria, Australia. The marked reduction we observed in live shrub cover is likely to persist for many years, given slow growth rates in this area: twelve months after the fire, median resprout height was 14 cm, and, at this rate, it would take at least eight years for the few surviving shrubs to attain the height of those in unburnt areas. ...
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The fires of summer 2003 in south-eastern Australia burnt tens of thousands of hectares of treeless alpine landscape. Here, we examine the environmental impact of these fires, using data from the Bogong High Plains area of Victoria, and the Snowy Mountains region of New South Wales. Historical and biophysical evidence suggests that in Australian alpine environments, extensive fires occur only in periods of extended regional drought, and when severe local fire weather coincides with multiple ignitions in the surrounding montane forests. Dendrochronological evidence indicates that large fires have occurred approximately every 50100 years over the past 400 years. Post-fire monitoring of vegetation in grasslands and heathlands indicates that most alpine species regenerate rapidly after fire, with >90% of species present 1 year after fire. Some keystone species in some plant communities, however, had not regenerated after 3 years. The responses of alpine fauna to the 2003 fires were variable. The core habitat (closed heathland) of several vulnerable small mammals was extensively burnt. Some mammals experienced substantial falls in populations, others experienced substantial increases. Unburnt patches of vegetation are critical to faunal recovery from fire. There was, however, no evidence of local extinction. We conclude that infrequent extensive fires are a feature of alpine Australia. For both the flora and fauna, there is no quantitative evidence that the 2003 fires were an ecological disaster, and we conclude that the flora and fauna of alpine Australia are highly resilient to infrequent, large, intense fires.
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Abstract Landscape fire (at the scale of square kilometres or more) is relatively rare in the alpine and subalpine environments of Australia. In early 1998, a major fire (the ‘Caledonia Fire’), burnt approximately 35 000 ha, of which approximately 3000 hectares was subalpine heathland, grassland and wetland within the Victorian Alpine National Park. This fire was one of only three landscape-scale fires that have occurred anywhere in the treeless vegetation of the Victorian Alps in the past 100 years, the others being in 1939 and 1985. Monitoring of regeneration in subalpine vegetation commenced 3 weeks postfire. Sites were established in burnt grassland at Holmes Plain (1400 m a.s.l.) and burnt grassland and heathland at Wellington Plain (1480 m a.s.l.), and in unburnt grassland at both sites. In burnt grassland and heathland, the fire consumed much of the vegetation, leaving extensive areas of bare ground. The cover of dense vegetation declined from > 70% prefire, to approximately 15% immediately postfire. Bare ground at the Holmes and Wellington Plains sites ranged from 70% to 85% immediately postfire. By May 2000, approximately 2.5 years postfire, dense vegetation cover in grassland had increased to approximately 20%, and bare ground had decreased to an average of approximately 30%. In unburnt grassland, dense vegetation cover was generally > 95%, and the amount of bare ground less than 5%. The tussock-forming snow grasses resprouted vigorously following fire, and had flowered prolifically after 1 year. In heathland, most of the shrubs were incinerated, leaving close to 100% bare soil. Since then, a number of grasses and some dominant shrubs have resprouted vigorously, with some seedling regeneration. By May 2000, in heathland, bare soil was still > 50% and dense vegetation Keywords: Caledonia Fire; alpine; bare ground; biomass; catchment protection; disturbance; fire regime; litter; vegetation cover Document Type: Research Article DOI: http://dx.doi.org/10.1046/j.1442-9993.2001.01151.x Affiliations: 1: Department of Agricultural Sciences, La Trobe University, Victoria, 2: Centre for Land Protection Research, Bendigo, Victoria and 3: CSIRO Sustainable Ecosystems, PMB 44, Winnellie Northern Territory 0822, Australia ( Publication date: December 1, 2001 $(document).ready(function() { var shortdescription = $(".originaldescription").text().replace(/\\&/g, '&').replace(/\\, '<').replace(/\\>/g, '>').replace(/\\t/g, ' ').replace(/\\n/g, ''); if (shortdescription.length > 350){ shortdescription = "" + shortdescription.substring(0,250) + "... more"; } $(".descriptionitem").prepend(shortdescription); $(".shortdescription a").click(function() { $(".shortdescription").hide(); $(".originaldescription").slideDown(); return false; }); }); Related content In this: publication By this: publisher In this Subject: Biology , Ecology By this author: Wahren, C-H. A. ; Papst, W. A. ; Williams, R. J. GA_googleFillSlot("Horizontal_banner_bottom");
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When disc-shaped horizontal slices of peat cores, three from a bog in mid-Wales and three from a bog in Hampshire, were kept for several months in a saturated atmosphere in a cool greenhouse numerous new shoots of Sphagnum papillosum (Lindb. S. magellanicum Brid. and S. recurvum P. Beauv. were produced. The new shoots arose on peat discs from at least 30 cm below the surface and water table and from regions in which the Sphagnum appeared to be brown and dead. A timescale, inferred from the cumulative dry mass and the peak in 137Cs concentration (which was assumed, conservatively, to reflect the 1963 peak influx), indicates that the matrix of the deepest discs from which new shoots arose was from 25 to perhaps 60 years old. Many of the new shoots of Sphagnum arose as innovations from the outer cortex of buried stems. In most cases the first leaves on these had the usual dimorphic leaf cell pattern. Other shoots, which initially produced leaves with monomorphic cells, arose from protonemata, comprising irregularly lobed plates of tissue and sparsely branched filaments with oblique cross-walls. A few of the protonemata arose from old stems, a feature not reported before, but the vast majority had no attachment to old plants and are thought to have grown from spores. Light and air were necessary if new shoots were to appear. But very few innovations or protonemata were found in the green discs from near the surface of the core. This suggests some kind of hormonal control of innovations akin to apical dominance in vascular plants and a more general allelopathic inhibition of spore germination and protonemal growth by green Sphagnum. Fern gametophytes of at least two taxa (Dryopteris-like and Pteridium-like) grew on the peat discs with distribution patterns similar to those of new Sphagnum shoots. Seedlings of five taxa of vascular plants – all species growing close to the core-sites – appeared on the peat discs but much more erratically than Sphagnum and the ferns. Stems of five species of leafy liverwort, presumed to have been derived from subterranean axes rather than from gemmae or spores, were also recorded, but no other bryophytes were seen. The discovery that morphogenesis in Sphagnum is far more fluid than hitherto assumed has far-reaching physiological, ecological and possibly genetical implications. The development of protonemata under semi-natural conditions, recorded here for the first time, confounds the results of culture experiments which had indicated that Sphagnum protonemata were unlikely to grow on peat.
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Knowing how species respond to fire regimes is essential for ecologically sustainable management. This axiom raises two important questions: (1) what knowledge is the most important to develop and (2) to what extent can current research methods deliver that knowledge? We identify three areas of required knowledge: (i) a mechanistic understanding of species’ responses to fire regimes; (ii) knowledge of how the spatial and temporal arrangement of fires influences the biota; and (iii) an understanding of interactions of fire regimes with other processes. We review the capacity of empirical research to address these knowledge gaps, and reveal many limitations. Manipulative experiments are limited by the number and scope of treatments that can be applied, natural experiments are limited by treatment availability and confounding factors, and longitudinal studies are difficult to maintain, particularly due to unplanned disturbance events. Simulation modelling is limited by the quality of the underlying empirical data and by uncertainty in how well model structure represents reality. Due to the constraints on large-scale, long-term research, the potential for management experiments to inform adaptive management is limited. Rather than simply recommending adaptive management, we define a research agenda to maximise the rate of learning in this difficult field. This includes measuring responses at a species level, building capacity to implement natural experiments, undertaking simulation modelling, and judicious application of experimental approaches. Developing ecologically sustainable fire management practices will require sustained research effort and a sophisticated research agenda based on carefully targeting appropriate methods to address critical management questions.
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A total of 128 invasive plant species have been recorded in treeless vegetation in the Australian Alps. Most of these are forbs and most are uncommon. Cover of invasive species is generally minimal unless there has been gross disturbance to natural vegetation and soils. Although there is a significantly positive correlation between invasive and native species diversity, suggesting that conditions that allow numerous native species to co-exist also permit more plant invasions, altitude is the most important determinant of invasive species diversity. Only 22 of the 128 species have been recorded above 1800 m. Some plant communities (e.g. those with high pH or relatively nutrient-rich soils), however, seem to be vulnerable to invasions regardless of altitude. Most invasive species appear to have been introduced unintentionally (e.g. as seed attached to vehicles, animals and humans) but a few were introduced to assist with revegetation of disturbed soils and for amenity plantings in ski resorts, and have subsequently established in native vegetation. Treeless communities in the Australian Alps are likely to face increasing pressure from invasive species as a result of global warming and continued introduction of non-native plants to ski resort gardens. Whilst it may be difficult to prevent invasive species of low elevations migrating to higher elevations as temperatures rise, the risk of invasion from garden plants could be minimised through regulation. Non-native plants in ski resort gardens pose a far greater risk than most invasive species currently present in the Alps because they have been chosen for their capacity to survive at high altitudes.