Fire Responses in Four Rare Plant Species at Gibraltar Range National Park, Northern Tablelands, NSW

2006·2.2 MB·English

by  Peter Croft

Fire Responses in Four Rare Plant Species at Gibraltar Range
NSW
National Park, Northern Tablelands,
^Peter Croft, ^Damien Hofmeyer and ^John T. Hunter
'Department ofEnvironment and Conservation (NSW), Parks andWildlife Division, Glen InnesArea, 68
NSW
Church St, Glen Innes, 2370
^Department ofEnvironment and Conservation (NSW), Parks and Wildlife Division, RichmondRiverArea,
NSW
ColonialArcade 75 Main St,Alstonville, 2477
^School ofHuman andEnvironmental Studies, University ofNew England,Armidale, NSW2351
Croft, P., Hofrneyer, D. andHunter, J.T. (2006). Fire response offourrare plant species at GibraltarRange
NationalPark,NorthernTablelands,NSW. Proceedings oftheLinnean SocietyofNewSouth Wales 127,
57-62.
Fire responses are reported in four rare species at Gibraltar Range National Park following hazard-
&
reduction buming. Acacia barringtonensis Tindale, Grevillea rhizomatosa P.M.Olde N.R.Marriot,
Persoonia nifa L.A.S.Johnson & P.H.Weston and Telopea aspera M.D. Crisp & P. H. Weston were the
species investigated. In each species, individuals were tagged prior to a hazard reduction fire and their
fates followed for 34 months. In Acacia barringtonensis, individuals survived fire and resprouted fi'om
buds atthebaseofstems andfi-omrhizomesbuttheresproutswereheavilybrowsedbyinsects andSwamp
Wallabies {WaUabia bicoJor Desmarest). In Grevillea rhizomatosa, individuals survived and resprouted
fi'om imderground rhizomes and no seedlings were found after fires. After fire in Persoonia rufa, all
scorched plants died but seedling recruitment occurred fi-om a soil-stored seed. In Telopea aspera, most
burnt individuals resprouted from basal shoots and survived despite heavy post-fire grazing pressure.
Increasing fire frequencies by hazard-reduction buming may threaten the survival ofall four species, and
it is suggested that other methods ofreducing fuel be used to manage fire in this area ofGibraltarRange
NationalPark.
Manuscriptreceived 1 May2005, accepted forpublication 7 December2005.
KEYWORDS:
fire ecology, fireresponse, obligate seeding, rare species, resprouting.
recommended for perpetuation ofmany species and
INTRODUCTION vegetation communities in the region (Clarke and
Fulloon 1997).
Hazard-reductionbumingforwildfiresuppression Fire can endanger the viability of species,
is thought to have recently increased in fire-prone especially if fire frequency is too high (Benson
DEC
vegetationaroundtheworld(Moritz etal. 2004; 1985; Bradstock et al. 1995; Keith 1996; Morrison
2004). This is particularly so on reserved lands in and Renwick 2000). Keith (1996) identified high fire
NSW NSW
where the Department of Environment frequencyasamechanismforplantpopulationdecline
and Conservation annual report (DEC 2004) noted and extinction through depletion of buds or starch
that there were twice the number ofhazard-reduction reserves in standing plants and also as a mechanism
bumsinNSWNationalParksin2003-04thanin2002- for depleting soil-stored seed banks before they can
03. Hazard-reduction buming may be initiated when bereplenished. Hence 'HighFrequencyFire'hasbeen
fiielbeginstoaccimiulatebeyondspecifiedthresholds listedas aKeyThreateningProcess inthe Threatened
(Gill et al. 1987; Morrison et al. 1996; Morrison and Species ConservationAct(TSC) 1995.
Renwick 2000; Femandes and Botelho 2003). On Some shrubs are killed by fire and, after fire,
the Northern Tablelands and similar areas, fuel may rely on seedling germination and a sufficient interfire
be kept at or below these thresholds by buming as period to survive and reproduce (obligate seeders),
often as every three to five years (Raison et al. 1986; whilst others resprout after fire (Benson 1985; Gill
& &
Smith et al. 1992). This is a higher frequency than Bradstock 1992; Morrison Renwick, 2000).
FIRE RESPONSES IN FOUR RARE PLANT SPECIES
The mean annual rainfall at Mulligan's
Hut is 2100 mm. The study area has a
mean annual temperature of13°C onthe
plateau with a mean aimual maximum
of 28°C and mean annual minimum of
0°C. Thewarmestmonths oftheyearare
November to March. The rock types are
primarily granitic and the topography
is generally undulating with extensive
areas of exposed rock sheeting and
s_
boulderfields.
The study area comprised four
hectares of open forest immediately
Glenlnnes
north of the Mulligan's Hut camping
area in Gibrahar Range National Park
where a small hazard-reduction bum
was scheduled in 1999. Mulligan's Hut
campingareaistowardsthecentre ofthe
ReserveBoundary
Gibraltar Plateau, at an altitude of 900
Road m. Thisbumwasplannedtohelpprotect
^ Town visitorsandfacilities inthecampingarea
i StudyLocation firom wildfire in the park.
The open forest community at this
Figure 1. Location ofMulligan's Hut study area within Gi localityisAormaaXeAhyEucalyptusolida
&
braltar Range National Park. L.A.S.Johnson K.D.Hill, Eucalyptus
ligustrina DC. and Eucalyptus
&
cameronii Blakely McKie. The shrub
However, fire responses in many species ofvascular layer is dominated by Leptospermum trinervium
plants in Gibraltar Range National Park are unknown (Sm.) Joy Thomps., Dillwyniaphylicoides A.Cunn.,
(Clarke andFulloon 1997; Williams andClarke 1997; Hakea laevipes subsp. graniticola Haegi, Petrophile
Hunter 1995; Hunter 1998; Hunter 2003; Clarke and
canescens A.Cunn. ex R.Br, and Daviesia umbellata
Knox 2002; Knox and Clarke 2004). Sm. The ground layer consists of: Caustisflexuosa
Within Gibraltar Range National Park several
R.Br., Platysace ericoides (Sieber ex Spreng.)
areashavebeensubjectedtohazard-reductionburning. C.Norman,Bossiaeaneo-anglicaF.Muell., Goodenia
One of them, Mulligan's Hut, contains populations
rotundifolia R.Br, and Entolasia stricta (R.Br.)
of four rare shrub species, Acacia barringtonensis
Hughes.
&
Tindale, Grevillea rhizomatosa P.M.Olde Prior to the hazard-reduction bum in 1999,
&
N.R.Marriot, Persoonia rufa L.A.S.Johnson NSW &
National Parks Wildlife Service fire records
&
P.H.Weston and Telopea aspera Crisp P.H.Weston. indicatedtwo large wildfires hadbumttheMulligan's
As fire responses of plants in each of these species Hut area in 1964 and 1988 with fire-history maps
were poorly known, fates of plants burned in a indicating the study site was bumt. Another fire
hazard-reduction fire in 1999 were recorded together occurred after the project was initiated in 2002 and
with any recruitment of seedlings of these species the subject populations were bumt during back-
after the fire. buming operations.
Target species
METHODS
Acaciabarringtonensisis anerectshmb endemic
to high altitude areas ofnorthem New South Wales
StudyArea
with a Rare or ThreatenedAustralian Plant (RoTAP)
Gibraltar Range National Park is located 90 code of 3RCa (Briggs and Leigh 1996). This shrub
km west ofGrafton and 65 km east ofGlen Innes in grows along swamp margins and creek edges in dry
north-eastemNewSouthWales(29°329 S 152°189E)
sclerophyll forests and woodlands reaching a height
(Fig. 1). The Gibraltar Range straddles the Northem of 7 m. Flowering occurs primarily from September
Tablelands and North Coast Botanical Subdivisions. to earlyNovember (Tindale 1975).
58 Proc. Linn. Soc. N.S.W., 127, 2006
p. CROFT, D. HOFMEYERAND T. HUNTER
Table 1. Percent survival oftagged plants in four species in relation to amount ofleafscorched during
a planned hazard-reduction burn in the Mulligan's Hut area ofGibraltar Range in 1999.
%
Leaf 1 3 5 7 34 Numberof
Species
Scorch month months months months months plants
Acacia
0-50 0% 100% 100% 100% 0% 2
barringtonensis
51-75 0% 100% 100% 100% 0% 1
76-100 0% 50% 57% 54% 7% 28
Grevillea
0-50 0% 100% 100% 100% 100% 2
rhizomatosa
51-75 0% 33% 67% 67% 67% 3
76-100 0% 20% 39% 57% 52% 49
Persooniarufa 0-50 0% 50% 50% 0% 0% 2
56-75 0% 100% 100% 0% 0% 1
76-100 0% 12% 6% 0% 0% 17
Telopeaaspera 100% 12% 94% 94% 94% 94% 17
Grevillea rhizomatosa is known from scattered identificationcodes. Eachindividualwasmarkedona
populations within Gibraltar Range and adjacent map ofthe study area, to aid relocation after the fire.
areas of Washpool National Park (Sheringham and Plant attributes measured included: basal diameter,
Hunter2002) andis listedon Schedule2 (Vulnerable) height, number of stems, location of regrowth,
onthe TSCAct. Itis ashrub0.3-1 mtall andisknown flowering stage, condition and number of seedlings
to sucker from roots and grows in sclerophyll forests nearby. All the individuals of Telopea aspera within
on sandy soils near creeks. The species flowers thestudyareaweretagged(17plants),thepopulations
sporadically throughoutthe year (see also Caddy and of the other three species were sub-sampled:
Gross this volume). Grevillea rhizomatosa (160 individuals). Acacia
PersooniarufaisendemictotheGibraltarRange. barringtonensis (62 individuals) and Persoonia rufa
It is a spreading shrub with a RoTAP code of 2RC (60 individuals).
(Briggs andLeigh 1996). Theplant commonly grows The intensity of the fire was gauged by using
to 1-2.5 m tall and is found in dry open forests on flame height markers, photographs and scorch height
granitic soils (Sheringham and Hunter 2002; Weston post bum. Measurements were taken of all tagged
and Johnson 1991). Flowering is primarily between plants before the experimental bum and at one, three,
December andFebruary. five, seven and 34 months after it.
Telopea aspera is a multistemmed shrub that
grows to 3 m tall and has a RoTAP code of 2RCa
RESULTS
(Briggs and Leigh 1996). It is largely restricted to
Gibraltar Range and is known from dry sclerophyll
forests on granitic soils. Flowering occurs between The Grevillea rhizomatosa population was
October and November (Sheringham and Hunter burned by a low-intensity fire (average flame height
2002; Crisp and Weston 1993). The flowering 0.75 m) that affected 54 taggedplants; 26 were bumt
response after fire has not been studied in Telopea and 28 were scorched by radiant heat. Grevillea
aspera. The closely related Telopea speciosissima is rhizomatosa responded to fire by increasing the
a pyrogenic flowerer and recruits two years after fire average number of stems per plant from 1.19 prior
(Pyke 1987; Bradstock 1995). to burning to 1.78 after being bumt. Although all
tagged plants unaffected by fire survived, only 55%
Fire response traits of fire-affected individuals were alive at the end of
Before the fire individuals of all four species the monitoring period (Table 1). Forty-five (83%) of
weretaggedwith stainless steel strapswithindividual all surviving fire-affected individuals recovered by
Proc. Linn. Soc. N.S.W., 127, 2006 59
FIRE RESPONSES IN FOUR RARE PLANT SPECIES
multiple rhizomes at a distance ofup to 30 cm (12 The immediate post-fire response of surviving
cm average) from the parentplant, andthe remaining Acacia barringtonensis was basal resprouting. These
nine plants recoveredby coppicing. resprouting stems were heavily grazed, which may
Alow-intensityfire(averageflameheight 1.07m) be a cause ofthe decline ofthis species towards the
burned theAcacia barringtonensis population where end ofthe monitoring period. Only at the last survey,
20 plants were burned and a fiarther 11 scorched. at 34 months, were putative seedlings noted in the
All tagged Acacia barringtonensis unaffected by vicinity of dead individuals. Subsequently, these
fire survived until the end ofthe monitoring period. 'seedlings' were revisited three years after the last
Although 17 fire-affected plants recovered from monitoring (May 2005) and were found to be shoots
basal stem buds by the 5-month post fire, only two from roots that extended back to 'dead' individuals
fire-affected individuals survived until the end of that were tagged. Thus it would seem that, though
monitoring.Mostoftheserecoveringindividualswere delayed by nearly three years, this species' response
heavilybrowsedbyboth insects and Wallabia bicolor to the hazard-reduction bum was resprouting. The
(Swamp Wallaby). No seedlings were recorded in delay may have been in part due to increased grazing
the first seven months within the vicinity ofaffected pressurethatinunediatelyfollowedthisfire. Increased
A. barringtonensis. However, at 34 months, 22 grazing pressure is not a necessary consequence of
putative 'seedlings'between 15-50 cm inheightwere fire. Indeed, following an extensive wild fire, it may
observed. be less than before the fire. However, small burnt
Twenty Persoonia rufa plants were burned with areas within large unbumt surrounding areas, such
a low-intensity fire (average flame height 0.75 m). as may arise from some hazard-reduction fires, may
All unbumt tagged Persoonia rufa individuals (40) be particularly attractive to browsing and grazing
surviveduntilthe endofthemonitoringperiod,butno animals and experience much more pressure from
individuals survived that were burnt (Table 1). Three them than surrounding unbumt areas.
scorched plants continued to survive for 5 months NoseedlingsofGrevillearhizomatosawerefound
afterthe fire. Within the study area 30 seedlings were during the monitoring period and populations appear
counted five months post-bum. All seedlings were of to be maintained by resprouting from underground
a uniform height (5 cm) and survived through until rhizomes. Keith (1996) noted that resprouters might
the lastrecording period. be killed if stored starch reserves are exhausted by
Flame heights exceeding five metres were repeated fires. Though numbers were too low for
recorded in the areas where Telopea aspera was statistical comparisons, more of the smaller plants
tagged. This resulted in 100% of the tagged plants in terms of stem diameter and height survived,
being burnt at moderate intensity. Ninety-four potentially indicating an age effect ability to recover
percent oftagged Telopea aspera plants survived the post-fire (seepaperbyBCnox and Clarke this volume).
moderate intensity bum. The sole means of survival The smaller Grevillea rhizomatosa plants in this
was by resprouting from the base/lignotuber. As a study may have depleted smaller quantities ofstarch
consequence of hazard-reduction buming, mean reserves. Following the second bum three years later
number ofstems per Telopea aspera plant increased about 65% of the original survivors of the hazard-
from 4.5 to 9.1. At least two individuals were noted reduction bum didnot recover from the secondfire.
resprouting after the first month, with all remaining Standing populations of Persoonia rufa
surviving plants resprouting by the second month individuals were the most susceptible to extirpation
and surviving to the final sample date (Table 1). by the end of the monitoring period from low-
Heavy browsing ofresprouting parts by insects and intensity bums. Although some temporary recovery
Swamp Wallabies {Wallabia bicolor) was observed occurred (due to coppicing after minor scorching),
on recovering plants after the fire. No plants had the species persisted in the fire-affected area mainly
floweredwithin the post-fire monitoring period. by germination from a soil-stored seed bank; hence
this species should be classed as an obligate seeder.
Telopeaasperawas the mostresilient interms of
DISCUSSION recovery ofthose individuals present before hazard-
reduction buming. Almost all of the tagged plants
Species responses survived to the end ofthe monitoring period, despite
Whilst many individual plants died as a result the imposition ofincreased (and heavy) herbivory on
of the hazard-reduction fire, all species persisted in newly forming foliage. This species respondedto fire
the study area by different fire response syndromes. by resprouting from basal/lignotuberous buds, with
60 Proc. Linn. Soc. N.S.W., 127, 2006
p. CROFT, D. HOFMEYERAND T. HUNTER
fire increasing the number of stems per plant post-
bum. Ofthe four species monitored, Telopea aspera ACKNOWLEDGMENTS
wasthefirstto show signs ofrecoveryafterfirebutno
seedHng recruitment was observed. DrKathrynTaffs isthankedforreviewingpreliminary
drafts. The staff of Department of Environment and
Implications Conservation(NSW)isalsothankedforprovidingassistance
Landscape burning at short intervals can have incarryingoutthehazard-reductionbumin 1999.Theinput
fromthe editors andreferees was appreciated.
major effects on plant populations (Bradstock
1995; Bell 2001) and may drive the decline ofplant
populations (Keith, 1996). Consequently, fi-equent REFERENCES
fire can have a significant effect on the composition
offlora and fauna (Clark 1988; Andrew et al. 2000; Andrew, N., Rodgerson, L. andYork,A. (2000). Frequent
York 2000; Moritz et al. 2004). The current study fuel-reductionbuming: the role oflogs and associated
has identified varied fire responses ofplants in four leaflitterin the conservation ofantbiodiversity.
rare species within Gibraltar Range National Park. AustralEcology25, 99-107.
Although populations ofall species persisted after a Bell, D.T. (2001). Ecological response syndromes in
hazard-reductionbum,mostwerereducedinnumbers theflora ofsouthwesternWesternAustralia: Fire
and at least two were affected by an increase in post- resprouters versus reseeders. TheBotanicalReview
67,417-440.
fire herbivory. This herbivory may have delayed the
regeneration of Acacia barringtonensis, and may Benson, D.H. (1985). Maturationperiods forfiire sensitive
shrub species in Hawkesbury sandstone vegetation.
have detrimental long-term effects on Telopeaaspera Cunninghamia 1, 339-349.
in terms of depleting starch reserves. As no plant in Bradstock, R.A. (1995). DemographyofWoodyPlants in
any ofthe four species flowered 34 months after the Relationto Fire: Telopeaspeciosissima. Proceedings
fire, fire intervals ofgreater than three years will be oftheLinnean SocietyofNewSouth Wales 115, 25-
neededto maintain theirpopulations. 33.
Hazard-reduction bums may have minimal Bradstock, R.A., Keith,D. andAuld, T.D. (1995). Fire
andconservation: imperatives andconstraints on
effects on the number ofwildfire events particularly
managing fordiversity. In 'Conservingbiodiversity:
in fire-prone vegetation (Tumer et al. 2003; Moritz et
threats and solutions' (EdsR.A. Bradstock, T.D.
al. 2004) and this is likely to be the case here at the Auld, D.A. Keith, R.T. Kingsford, D. Lunney and
Mulligan's Hut site (e.g. the 2002 fire that effected D.R Sivertsen) pp. 323-334 (Surrey Beatty and Sons,
the Mulligan's Hut area). Though hazard-reduction ChippingNorton).
bums are plarmed, wildfire events are not, thus by Briggs J.D. and LeighJ.H. (1996). 'Rare orThreatened
increasingthe amountoffire inthe landscape without Australian Plants'. (CSIRO publishing,
being able to predict wildfires there is an increased Collingwood).
risk of population decline and extinction. Whilst Clark, S.S. (1988). Effects ofhazard-reductionbuming
onpopulations ofunderstoreyplant species on
hazard-reduction buming can reduce the intensity of
Hawkesbury sandstone.AustralianJournalof
awildfire forseveral years (Raisonet al. 1986) itmay Ecology 13, 473-484.
notpreventtheareafromre-bumingduringawildfire,
Clarke, RJ. andFulloon, L. (1997). 'Fire andrare
especially in severe fire weather (Tumer et al. 2003; plants: Torrington State RecreationArea. Botany
Moritz et al. 2004). Additionally, hazard reduced Department'. (University ofNewEngland,
ground is often chosen as an area from which back Armidale).
bums are plarmed during wildfires control operations Clarke, P.J. and Knox, J.E. (2002). Postfireresponse
because of lower fuel levels. If hazard-reduction ofshrubs inthetablelands ofEasternAustralia:
buming is undertaken at the maximum frequency do existingmodels explainhabitat differences?
AustralianJournalofBotany 50, 53-62.
without considering unplanned fires then critical
Crisp, M.D. andWeston, PH. (1993). Geographic and
thresholds of fire frequency for long-term survival ontonogenic variation in morphology ofAustralian
of populations can be exceeded as has occurred at Waratahs {Telopea: Proteaceae). SystematicBiology
Mulligan's Hut. To ensure thepersistence ofourfocal 42, 49-76.
species a fire interval that allows seedlings to mature Department ofEnvironmentandConservation (2004).
and a seed bank to accumulate is required. Whilst Annual Report. DepartmentofEnvironment and
these demographic factors are yet to be quantified it Conservation (NSW). Sydney.
is suggested that the minimum interval between fires Femandes, RM. andBotelho, H.S. (2003).Areview
to ensure the persistence ofthe focal species will be ofprescribedbuming effectiveness infire hazard
more than ten years.
Proc. Linn. Soc. N.S.W., 127, 2006 61
FIRE RESPONSES IN FOUR RARE PLANT SPECIES
reduction. InternationalJournalofWildlandFire 12, Turner, M.G., Romme,W.H. andTinker, D.B. (2003).
117-128. Surprises andlessons fi-omthe 1988Yellowstone
Gill,A.M. andBradstock, R.A. (1992).Anational register fires. Frontiers inEcologyandtheEnvironment 1,
forthefire responses ofplant species. Cunninghamia 351-358.
2, 653-660. Weston, P.H. andJohnson, L.A.S. (1991). Taxonomic
Gill,A.M., Christian, K.R., Moore, P.H.R. andForrester, changes inPersoonia (Proteaceae) inNew South
R.I. (1987). Bushfire incidence, firehazard and fiiel Wales. Telopea4, 269-306.
reductionburning.AustralianJournalofEcology 12, Williams, P.Rand Clarke PJ (1997). Habitatsegregation
299-306. by serotinous shrubs inheaths: postfire emergence
Hunter, J.T (1995). Some observations onthefire and seedling survival. AustralianJournalofBotany
responses oftwo rare species inthe Girraween and 45,31-39.
BaldRockNational Parks. QueenslandNaturalist35, York,A. (2000). Long-term effects offrequent low-
5-6. intensityburning on ant communities in coastal
Hunter, J.T. (1998). Notes onthe occurrence ofMonotaxis Blackbutt forests ofsouth-easternAustralia.
macrophyllaBenth. (Euphorbiaceae), withparticular
AustralEcology 25, 83-98.
reference toNew South Wales. Queensland
Naturalist36, 21-24.
Hunter, J.T. (2003). Persistence on inselbergs: therole
ofobligate seeders andresprouters. Journalof
Biogeography 18, 497-510.
Keith, D. (1996). Fire-driven extinction ofplant
populations: a synthesis oftheoryandreview of
evidence fromAustralian vegetation. Proceedings of
theLinnean SocietyofNewSouth Wales 116, 37-78.
Knox, K.J.E. andClarke, P.J. (2004) Fireresponse
syndromes ofshrubs in grassywoodlands in theNew
EnglandTablelandBioregion. Cunninghamia 8, 348-
353.
Moritz, M.A., Keeley, J.E., Johnson, E.A. and Schaffher,
A.A. (2004). Testingthebasic assumption of
shrublandfire management: how important is fiiel
age?Frontiers inEcologyandtheEnvironment2,
67-72.
Morrison, D.A., Buckney, R.T., Renwick, B.J. and Cary,
G.J. (1996). Conservation conflicts overburningbush
in south easternAustralia. BiologicalConservation
76, 167-175.
Morrison, D.A. andRenwickJ.A. (2000). Effects of
variation infire intensity onregenerationofco-
occurring species ofsmall trees inthe Sydneyregion.
AustralianJournalofBotany48, 71-79.
Pyke, G.H. (1987). Pollinationbiology ofTelopea
speciosissima. In 'Waratahs-theirBiology,
Cultivation and Conservation' (Ed. J.A.Armstrong)
pp. xx-xxAustralianNational Botanic Gardens.
Occasional PublicationNo. 9.
Raison, R.J., Woods, RV. andKhanna, RK. (1986).
Decomposition and accumulation oflitterafterfire
in sub-alpine eucalypt forests.AustralianJournalof
Ecology 11, 9-19.
Sheringham, P. andHunter, J.T. (2002). Vegetationand
floristics ofGibraltarRangeNational Park. (Areport
NSW &
to the National Parks Wildlife Service).
Smith,A.R, Moore, D.M. andAndrews, S.R (1992).
ProposedForestry Operations inthe Glen Irmes
ManagementArea, FaunaImpact Statement. Prepared
forthe Forestry Commission ofNew SouthWales.
Tindale, M.D. (1975). Notes onAustraliantaxa ofAcacia
No. 4. Telopea 1, 68-83.
62 Proc. Linn. Soc. N.S.W., 127, 2006