Changes in Vegetation Structure and Floristics under a Powerline Easement and Implications for Vegetation Management

2006·2.3 MB·English

by  Trevor, Adams Meers

2
Research Reports
Changes in vegetation structure and floristics under a
powerline easement and implications forvegetation management
Trevor Meers1 and Robyn Adams'
Abstract
Utility corridors such as powerlines are widespread lineareasements ofhighly modifiedvegetation
whichoftenfragmentnaturalareasofconservationsignificance. Vegetationmanagementalongthese
easements is aimed at modifying vegetation structure by the removal ofall tall shrubs and trees,
whichmayhaveadverseimpactsonfloraandfaunadiversity. Victoria'sBunyipStateParkisbisect-
ed by ahigh voltagepowerlineeasementwhich ismanaged bya fouryearslashingcycle. Repeated
slashing has alteredplant species composition and structure ofthe drierslope and ridgevegetation
comparedtounslashedadjacentOpenForestvegetation, butWetHeathwithinthemanagementzone
has remained largely unmodified. At a broad level, plant species diversity in the easement is
increased,andhighervegetationdensity hascreatedsmall mammal habitat. Thepowerlineeasement
didnotappearto facilitateweed invasion. Vegetation management by repeatedslashinghas altered
the vegetation, but does not appear to have had adverse conservation impacts on local plant and
smallmammaldiversity.(TheVictorianNaturalist123(1),2006,29-37)
Introduction
Utility corridors such as powerlines, gas areas converted to shrublands (Kroodsma
pipelines and water pipelines are wide- 1982). This type of vegetation manage-
spread linear easements, often encompass- ment is not unique to utility easements,
ing a surprisingly large total land area and often occurs along other linear corri-
(Knight et at. 1995) and, in some cases, dorssuchasroad vergesandfirebreaks.
representing an important component of There are concerns that easements have a
the regional landscape (Hill et at. 1995). significant impact on conservation values
These corridors arc usually highly modi- by loss of habitat and biodiversity, and
fied strips of vegetation passing through invasion ofexotic species. Changes to the
tracts oflittle-modified native vegetation, vegetation composition and structure can
and dissecting and internally fragmenting result in changes in native fauna
natural areas ofconservation significance (Goldingay and Whelan 1997). For exam-
(GoldingayandWhelan 1997). ple, where rainforest vegetation was con-
The most noticeable visual impact of verted to grassland, the small mammal
these corridors is the loss oftree coverand community also changed from rainforest
the associated simplification ofvegetation species to grassland specialists (Goosem
structure. Regular slashing to reduce bio- and Marsh 1997). Avifaunal studies (e.g.
mass levels for fire safety (ChiefElectrical Rich et at. 1994; Baker et ai 1998) sug-
Inspector 1999), and applications ofherbi- gest that utility easements may contribute
cidestopreventregrowthenteringthe wire to the decline of forest-interior bird
security zone (Hill et at. 1995) are major species, and may contain a species-poor
ongoing management practices. In these subset ofthe birds found in the surround-
powerlinc easements, vegetation regrowth ing forest. The new habitattype createdby
of shrubby seedlings and coppice from tree removal and corridor management
stumps and lignotubers is usually managed facilitates invasion by non-forest bird
by repeated slashing, spraying with herbi- species andexotic bird species. The role of
cides, or grading (Goosem 1997). Native easements in facilitating the penetration of
vegetation may be completely replaced by dogs, cats and foxes into natural areas also
exotic grasses or woody shrubs (Goosem has been investigated (Andrews 1990;
and Marsh 1997), or previously forested Catling and Burt 1995; Lindenmeyer et at.
1994; Goldingay and Whelan 1997), and
'School of Kcology and Environment, Dcakin
University,221 BurwoodHighway,Burwood,Victoria access roads and maintenance activities
[email protected] associated with easements may be a source
: present address School ofForest and Ecosystem of weed invasion (Parendes and Jones
Science,UniversityofMelbourne,WaterSt,Crcswick,
[email protected]
Vol. 123 (1) 2006 29
Research Reports
2000; Lonsdale and Lane 1994; Tyser and Victoria 1998). The Park contains about
Worely 1992). However, the relatively 400 vascular plant species (Parks Victoria
dense ground cover promoted by slashing, 1998). The sectionofthe Park in which the
and selective use of herbicide in some study was carried out has Botanical
types of easement vegetation, appear to Significance as it contains Wet Heathland,
provide suitable habitat for small native a rare vegetation community in Victoria,
mammals (Macreadie et al. 1998; and a population ofrare Swamp Bush-pea
Goldingay and Whelan 1997; Pearce Pultenaea glabra (syn. P. weindotferi)
2003), and vegetation management has the (Fraseretal. 2004). The Heathy Woodland
potential to maintain, or even increase, is also of Regional Significance (Parks
uncommon habitat suitable for rare Victoria 1998).
species. The study site was a section ofthe pow-
This study aimed to investigate the erline easementbetween Peppermint Track
effects ofmanagement ofa powerline on and the Bunyip River aqueduct, and
native plant species composition and vege- encompassed approximately 1.2 km ofthe
tation structure, and to comment on the easement in the south east ofthe Park. The
conservation implications ofcurrent pow- powerlinc cuts through Open Forest and a
erline management. vehicle access track follows the easement,
which isdissectedbyaseriesoflow ridges
Study Site and Wet Heathland drainage lines (Fig. 1).
Bunyip State Park, Victoria, covers 16 These drainage lines create relatively con-
622 ha in the foothills of the Great tinuous cover from one side of the ease-
Dividing Range, and is bisected by a 500 ment to the other. Due to the topographic
kV electricity transmission line running position of the drainage lines they are
from the southeast to the northwest ofthe rarely, if ever, slashed during routine
Park. This easement was established in maintenance operations. This section of
1962 and has been repeatedly slashed on a powerline was investigated by Macreadie
fouryearcycle (Macreadieetal. 1998). e(aL(1998).
The Park contains a variety ofvegetation The modified vegetation under the pow-
types ranging from Closed Forest and erline contains a wide diversity ofspecies
Mountain Ash-dominated Tall Open and is a mix of open, heathy areas and
Forest, through Open Forest to Heathy grassy areas with- emergent shrubs. The
Woodland and Wet Heathland (Parks
forest vegetation on eitherside oftheease-
Fig. 1. Povverline easement through Open Forest, Bunyip State Park. Thevehicle access track runs
the length oftheeasement, andthe undulatinglow ridge drainage line nature ofthetopography is
visible.
30 The Victorian Naturalist
Research Reports
ment at this location is mainly Mealy side ofthe access track. To minimize any
Stringybark Eucalyptus cephalocarpa- edge effects, all quadrats in the easement
dominated Open Forest, with a heathy were placed at least 10 m from the track,
understorey containing several species of and quadrats in the forest were at least 10
Banksia, Hakea and Acacia. The ground m from the easement edge. Species pres-
layer is dominated by Wiry Spear-grass ence, and cover, estimated using a modi-
Stipa muelleri and several sedge species. fied Domin Cover Scale (Kershaw and
Open Forest dominated by Eucalyptus Looney 1985), were recorded. Quadrat
ohliquaand Eucalyptusradialaalsooccurs data were investigated for floristic patterns
along this section ofthe easement. Trees using both classification and ordination
are absent from the drainage lines that run techniques (PATN analysis package,
through the easement, and these drainage Belbin 1991), and species in each quadrat
lines are dominated by Wet Heathland were clustered usingthe Bray-Curtis asso-
containing Prickly Tea-tree Leptospermum ciation measure with fusion using Wards
continentaleand GahniaradulaorScented method (Belbin 1991). Plant cover is dis-
dPeanpseerbuanrdkerMsteolraelyeuofcaPosuqcuhaerdroCsoaralwiFtehrna ptola5y.edPl(aTnatblneom1e)nocnlaatruerlaetifveolslcoawlse fWraolmsh1
Gleicheniadicarpa. and Lntwisle(1994).
Methods Understorey structure to a height of 120
Square quadrats (25 nr) were placed at cm was determined umsing a graduated
i1n0g0 mat iPneteprpvaelrsmialnotngTrthaeckeasaenmdenetndstianrtg- svterguecttautrieonpoqluea,daralto.ngT2h0e nutmrbaensrecotfsvaetgeeatcah-
aRpipvreorxAiqmuaetdeulcyt.1.T2eknmquaawdaryatsatwtehreeBpulnayciepd ptioolnecoisntcacotnsveinrteeadchto10acpmericnetnertvaagleo,natnhde
in the forest on each side ofthe easement, allows comparison ofvegetation cover at
andten in theeasement, with five oneither horizontal intervals vertically through the
understorey(Fig. 2).
la)drainayelines.-easement
(c)slope/ridge-easement (d)slope/ridge-forest
Fig.2. Comparisonoftheunderstoreystructureprofilesforthepowerlineeasement(aandc)andthe
surroundingOpenForest(bandd).
Vol. 123 (1)2006
31
Research Reports
The structure data were pooled into four slope/ridge vegetation comprised mainly
arbitrary strata(0-30 cm, 30-60 cm, 60-90 low shrubsandStipamuelleri.
cm and 90-120 cm) for each ofthe four
Speciescompositionandcover
locations (easement siope/ridge, easement
drainage lines, forest slope/ridge and forest Approximately 80 species were recorded,
drainage lines) and compared using two- including 55 dicots, 14 monocots and 8
way ANOVA. Data were examined for ferns. The only exotic species recorded in
quadrats were Cirsium vulgare and
normality and homogeneity of variances,
andthepercentagedataarcsinetransformed Hypockocris radicata and two unidentified
for analysis. The differences between sig- herbs. EricalusitunicuandAcacia longifolia
nificant means were examined using were infrequently observedgrowing in scat-
Newman-Keuls multiplecomparisonstest. teredlocationsadjacenttotheaccesstrack.
The classification dendrogram (Fig. 3)
Results indicated two primary vegetation types
Vegetation structure corresponding to drier vegetation from
ANOVA
results indicated a significant slope/ridge quadrats (Type 1) and vegeta-
interaction between locations and structure tion from Wet Heath or drainage line
(Fy.374 = 5.83, p < 0.001). Newman-Keuls quadrats (Type 2). Both these vegetation
multiplecomparisonstestsshowedthat veg- types could be subdivided into three vari-
etation structure differed significantly (p < ants, and each vegetation type was identi-
0.05) in density in two strata for the fied by high cover ofa characteristic suite
slope/ridge locations in the easement com- ofspecies(Table 1).
pared with the slope/ridge locations in the
surrounding forest (Fig. 2c and 2d). Vegetation types
Vegetationdensitywasnotsignificantly dif- Vegetation Type 1: Eucalyptus Open
ferent in the 0-30 cm orthe 60-90 cm lay- Forestand derivatives
ers. In the easement, the vegetation layer la. Eucalyptus Open Forest: This
between 30 and 60 cm was significantly Eucalyptus cephalocarpa-dominated Open
mmoosrtelydednuseeto(pa<hi0g.h0e5r)ctohvaenrionftghreassf,oreasntd, tFioornesstofisBwuindyeispprSetaadtetPharroku,ghantdhemdaryiergrsaedce-
vegetation was very sparse beyond 90 cm. into Heathy Woodland. It is found on both
In the forest, the vegetation structure was sides ofthe easement on drier slope/ridge
slightly more complex with a sparse layer sites, and is the original forest type that
ofvegetation in the90-120cm stratum occurred on the easement prior to modifi-
The structure of the vegetation in the cation.
drainage lines was similar regardless of lb. Originally Eucalyptus Open Forest of
whether the drainage lines were in the Type la. Although there is some regrowth
ofthe canopy, the diversity ofunderstorey
easement or in the surrounding forest (Fig.
2a, 2c and 2b, 2d). The only significant shrubs isextremely low. This foresttype is
difference (p < 0.05) w'as slightly thicker found in the easement along the forest
vegetation between 60 and 90 cm in forest edge, and results-from slashing and partial
regrowth following disturbance during the
drainage lines compared with those in the
originalpowerlinc construction.
easement.
The vegetation in the drainage lines is lc. Stipa muelleri grasslandwith emergent
shrubs of Acacia, Pultenaea Epacris,
structurally different compared to the ,
Banhsia, Dillwynia and a dense cover of
slope/ridge vegetation (e.g. Fig. 2a to 2d).
Apart from the 0-30 cm layer, drainage Caustisjlexuosa and Gahnia radula. This
line vegetation was generally thicker than is equivalent to the Acacia-Banksia type
theslope/ridgevegetation, especially in the described by Macreadie el al. (1998), and
taller strata (60-90 cm and 90-120 cm). is secondarygrassland with stuntedshrubs,
formed by the removal of the Eucalyptus
oThfiesitdhiefrferLeenpcetoisspdeuremtuomthceondteinnseentthailcekeotrs canopy ofType la and subsequent fre-
Melaleuca squarrosa with understories of quentslashing. This vegetation type is also
Gleichema dicarpa, Ghania radula or characterized by a high incidence of bare
Bauerarubioidesinth,edrainage lines. The ground. It was found only on slope/ridge
siteswithintheeasement.
32 The Victorian Naturalist
Research Reports
0%
j
i
Vegetation Type / VegetatiIon Type2
£nca/t'jp/ifsOpen Forest& WetHeath &
derivatives on stopes/ridges
drainagelines
1
33
j
%
50
s-
T3
«3 i
a
4>
a:
100% icSfipu lb ta OEpuecnalFyoprteusst Ck2ts»h\mjacWpettwpHeeramtthm- 2b K2kekiSeuca
mue/feri
Fig. 3. Classification dendrogram showing the clustering ofquadrats into two primary vegetation
types - Eucalyptus Open Forest and derivative on slopes/ridges (Type 1) and Wet Heath and
drainagelines(Type2).
Vegetation Type 2: Wet Heath and Theyarefound indrainagelinesinboththe
drainagelines easementandforest. Theyarenotslashed.
2a. Leptospennum continentale - Gahnia
Discussion
raclula Wet Heath: There isa high diversi- Vegetation management along utility
tayndofBamuonmoecaottsetrsaugcohnaa.sGTleetircahreinaicaadpiilclaarrpias easements is aimed at modifying vegeta-
tion structure by the removal oftall shrubs
fiadsolrrsaeuoisstnua.aabgluMelnoydsalitnpntre.eossfeIitntnthi,esbofaatornheudantdShcteoiipvnceeiwaresemtdeumesbeliynlteetstrhiaaennsiddes amdvanaetdgnieaottgrneaeetamsin,eodnantnldorsweisotsumoplfiodgndhsirtveeesbruestlitoteyixd.npiehsHcatotbuwiertedabvttaehnrdace,tgetrthahii-ess
drainage lines is too wet or inaccessible to dependent on the original vegetation type,
s2lba.shA. variant ofLeptospermum continen- and the individual management treatments
ttailneg-uiGsahhendiabyraaduhliaghWectovHeeartho:fIBtaiusedirsa- rusoepdh.ylRlepfeoaretsetdisnlatshheinAgutshtrroaulgihandrCyapsictlael-
Territory altered the vegetation structure
rubioides and the absence ofmost species by promoting eucalypt suckering and
found in Type 2a. There is a scatter of increasing the densityofunderstorey vege-
species not found in the other vegetation
tation compared with unslashcd adjacent
types, suchas Olearia ramu/osa. This veg-
etation type was the only one in which forest (Bell 1980). Vigorous suckering
Acaena novae-zelandiae and Cirsium vul- from stumps and roots is also reported
gleasrsewweterseecftioounnsd.ofItdriasifnoaguendlionenslyanidnwtehte at1fa9tt9eir1o)nf,rieanqnudeNnostrutschlkaesArhiminenggriowcfaaspo(cwLoenurtlkrieonnleleevtdegabety-.
sites in the easementwhereslashingispos- herbicide applications. An easement
sible. It probably represents a more dis- through Queensland rainforest was con-
turbedvariantofType2a.
t2ch.ickMeetlsaalreeuccaharsaqcutaerrrizoesdabtyhiacknetesx:trTehmeesley veesrtoefdwtoooddeynseweeexodtsic(gGroaosssleamndaannddMpaatrcshh-
1997), and exotic grasslands and shrub-
dense Gleichenia dicarpa understorey.
Vol. 123 (1)2006 33
a a
Research Reports
Table 1. Floristiccompositionofvegetationtypes 1 and2. Exoticspecies= *. Quadrats(n=40)are
displayedacrossthetable,andthespeciespresentare listedvertically,withthevalues 1 5represent-
ingrelativecover. PlantnomenclaturefollowsWalshandEntwisle(1994).
Species Type 1c lb la 2a 2b 2c
Stipa Eucalyptus Wet Heath Melaleuca
Leptospermum |11 1113 | 1111 1121111111111213 | widspread
continentale
Gahniaradulci |523111 [211 |1 11111111111 ]2413 51311 |5235 [21 3 species
Eucalyptusradiata 24 1322 5
Eucalyptuscephalocarpa 22121 221214
Eucalytusobliqua 32
Lycopodium 11
deuterodensum
Banksiaspinulosa 1 111 5 species
Xanthorrhoeaminor Ill 1 restricted
Banksiamarginat 111 12 tooriginal
Daivestaleptophylla 111111 OpenForest
Lomatiailicifolia 1 1 1
Hakeanodosa 1
Exocarposcupressiformis 1
Hakeateret[folia 1 1
Gompholobiumhuegelii 1
Tetrathecaciliata 1
Stipamuelleri 535555 555 5555555555555 12 555 15 53
Bareground 52222 1 31 1 widespread
Acaciaoxvcedrus mu1 121 1111 113 1 species
Acaciagenistifolia 11 1111 1 1 12 1 1 1 fromall
Pidtenaeagunnii 1211 1 11 111 1111 1 111 1313 sites
Dampierastricta 11 1 1 1 1 exceptthe
Moss 111 111 1 mi 1 wettest
Ampereaxiphoclada 1 111 11 1 sites
Pteridiumesculentum 1 1 2 1 1
Caustisflexuosa 5531 1 ini i in 1 111
Monotocascoparia 111 i i widespread
Lepidospermalaterale 1m1i11n1 112 1 1 species,
Epacrisimpressa mm 1 1 11 1111 butmissing
Dillwvniaglaberrim m 1 1 1 1 111 fromdis-
Leptospermum i 11 1 113 turbedsites
mvrsinoides (lb)and
AHcoavceiaalaicnuelaeriastissima ii 11 111 i i 1 wsiettetsest
Hakeaulicina n i 1 1 2 11 1 1 (2band2c)
Ilakeadecurrens l 111 111 111 1
mi
Eucalyptusseedlings 1 1 1
Goodenialanata l
Acaciamvrtifolia n l i
Lomandralongifolia l i 1 species
Violacleistogamoides i i mostly
Stylidiurngraniinifolium i 1 foundin
Acaciabrownii l frequently
PKeurnszoeoaniearijcuoniidpeesrina l n ssiltaesshed
Acrotricheserrulata i
GHyodnrooccaortpyulsemlaixcirfalnortahus in 11 111 1 1
*Hypochoerisradicata i 1 1
Bauerarubioides 12 1 2 1 131 5 1 2555 22 species
Tetrariacapillaris 55 511135 1 1 ofwetter
Baumeatetragona 5 1 1 12 sites
Tetrarrhenajuncea 2 51 1 1
34 The Victorian Naturalist
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Research Reports
Table 1 cont'd.
Species Typelc lb la 2a 2b 2c
Stipa Eucalyptus WetHeath Melaleuca
1111
Leptocarpustenax i
1 1 1 1
Pultenaeaglabra i 1 1 1 13 11 1 1
Epacrisgunnii i 1 1 1 1 1 1 species
Lobeliaelata i 1 1 11 1 1 confined
Selagineftauliginosa i 1 1 111 1 1 toWet
Lindsaealinearis i 11 1 111 1 1 Heath(2a)
Seneciominimus i 1 1 11 1 1
Euphorbiaspp. i 1 1 11 1 1
Melaleucasquarrosa 131 mi
i 1 1 1 1
Gleicheniadicarpa i 1 1 11115 1 1 15555 wetsites
Leptospermumlanigerum i 1 1 1 1 1 11 with
Epacrisobtusifolia i 1 1 1 1 1 1 1 high
ERemsptoioditsetmraapmhiylnluuss i 1 1 11 11 1 1 1 111 cGolveeicrhoefnia
i 1 1 1 1
Patersoniafragilis i 1 1 1 12 1 1 1 1
Acaenanovae-zelandiae i 1 1 1 132 1
*Cirsiumvulgare i 1 1 1 111 1 uncommon
Cassythaglabella i l 1 1 1 111 1 species
Cyatheaaustralis i 1 1 1 1 111 1 ofwetter
Oleariaramulosa i 1 1 1 1 1 1 sites
Olearialirata i 1 1 1 1 11 1
Ozothamnusferrugineus i 1 1 1 1 11
Juncuspallidus 1 1 1 1 11 uncommon
Carexspp. i 1 1 1 1 11 species
Dicksoniaantarctica i 1 1 1 1 11 ofwettest
BBlleecchhnmiunrinncaurdtiulmagineurn i 1 1 1 1 11 sites
i 1 1 1 1 11
lands developed in easements through Forest(Type la) (35 species) and the mod-
hardwood and softwood forests in ified vegetation of Type lb (38 species)
Tennessee (Kroodsma 1982). In all these were very similar. Species other than the
instances, the vegetation composition was canopy eucalypts and S. muelleri rarely
considerably altered from that of the adja- had cover values greater than 20% projec-
cent forest vegetation. In these examples, tive foliage cover.
vegetation structure was similar with no However, a comparison of the composi-
emergent shrubs ortrees and a more dense tion ofthe original EucalyptusOpen Forest
layer ofgrasses orgrasses with low shrubs (Type la) and the Stipa muelleri grassland
in the disturbed areas. (Type lc) showed a difference in the
The response of the Open Forest along species present. Seven shrub species
the BLinyip easement is generally consis- recorded in the Open Forest were not
tent with this pattern of structural change. recorded in theS. muellerigrasslandon the
The drier sections of the easement have easement. These were shrubs with a seroti-
been converted to Stipa muelleri grassland nous seed store such as Banksia spimtlosa
,
with patchy low shrubby species, while the Banksia marginata Lomatia ilici/olia,
,
wetter drainage lines show little change Hakea nodosa and Hakect teretifolia, and
between forest andeasement. the ant-dispersed shrubs Daviesia lepto-
Some changes in floristics were identi- phylla, Gompholobium huegelii and
fied. The original Eucalyptus Open Forest Tetratheca ciliata. Seeds dispersed by ants
(Type la) understorey is composed of a are typically dispersed about one metre,
diversity of shrubby species, Stipa limiting species' ability to recolonise once
muelleri, and other monocot species typi- eliminated. Also absent from the modified
cal ofVictorian dry heathy Woodlands and easement vegetation (Types lb and lc)
Open Forests. Overall, the total numbersof were Xanthorrhoea minor and Exocarpos
species recorded in the Eucalyptus Open cupressiformis.
a
Research reports
Substantial areas ofbare groundoccurred tive herbicides as easement management
in the Stipa muelleri grassland. Caling techniques, and avoidance of soil disturb-
(1998) found that a number ofspecies of ing techniques such as grading. Weeds
low-growing sedge and herb had higher were recorded only in the easement.
cover in soil-disturbed, linear firebreaks Hypochoeris radicate, Cirsium vulgare
compared with the surroundingvegetation. and two unidentified weedy species were
These bare areas may provide colonisation recorded from quadrats, although Spanish
sites forspecieswith clonal orrhizomatous heath Erica lusitanica and Acacia longifo-
growth mechanisms such as some ferns, liaweregrowingalongaccess roads.
herbs and ground covers, and are repre- Vegetation structural changes resulting
sented in the Stipa muelleri grassland by from frequent slashing may disadvantage
Gonocarpus micranthus Hydrocotyle laxi- some small mammal species such as
,
fgalrmoaormiaid,neiGsfo,oolLdioeumnmainaSderllaaagnialnotenalg,lifaVoiluoillaia,giScntloyeslieisdtaionugdm- Adhneanbtsieticathtyinsiususitthaaebgiillmiiastiy,nbfuoftracbmteoacrnacyuosnestmrvaielbgluettimanatgimot-no
Lindsaea linear,is These species also may mals (Monamy and Fox 2000), the Stipa
.
be responding to increased light. Five muelleri (Type lc) grassland in the ease-
shrubby species recordedonly in the Stipa ment provides quality habitat for species
muelleri grassland were Acacia myrtifolia. such as Rattus fuscipes (Macreadie et al.
Acacia brownii, Persooniajuniperina and 1998; Pearce2003).
Acrotriche serrulate, and the shrubby col- Goldingay and Whelan (1997) suggested
onizer Kunzea erieoides. The exotic that small mammals would use densevege-
Hypochoerisradicatealsowaspresent. tation and habitat linkages within case-
The floristiccompositionand structureof ments, and this is supported by this study.
Leptospennum continentale - Gahnia The structural similarity ofthe Wet Heath
radiil Wet Heath (Type 2a) and (Types 2a and 2c) in the easement and the
Melaleucasqitarrosa thickets (Type 2c) in Open Forest enables this vegetation to be
the drainage lines showed little difference used as a link across the easement. Several
between theeasementand the adjacent for- mammal species have been trapped more
est. The drainage lines are generally too frequently in Wet Heath vegetation com-
wetto slash, and haveno emergent treesto pared to the surrounding slopes/ridge vege-
threaten the wire security zone. Only the tation. These included the rare Broad-
more accessible and less wet drainage line toothed Rat Mastocomysjuscus, Dusky
edges near the access track appear to be Antechinus Antechinus swainsonii
regularly slashed, and it is here that the (Macreadie et al.1998), and Swamp Rat
variant of Leptospennum continentale - Rattus lutreolus (Macreadie et al. 1998;
Gahnia radula Wet Heath (Type 2b) with Pearce 2003). The frequency ofoccurrence
a few weedy species is found. The rare ofMastocomysjuscus was highestin vege-
Swamp Bush-pea Pultenaea glabra (syn. tation with high cover ofBauera rubioides
PH.eawtehisnidtoesr.feri) is limited to these Wet (sMtaucdryeatdhiaetestlaals.h1i9n9g8)d.iIsttauprpbeaanrcsefrtoomWtehits
Although intact forest vegetation appears Heath (Type 2a) results in increased cover
to be relatively resistant to weed invasion ofBauerarubioides(Type2b)andit is like-
(Brothers and Spingarn 1992), roads and lythatthe slashing regime in this section of
linear easements continue to be identified the powerline easement has increased suit-
as potential invasion corridors for exotic ablehabitat forMastocomysjuscus.
weeds (ParendesandJones2000; Lonsdale This study suggests that repeated slash-
and Lane 1994; Tyser and Worely 1992). ing ofvegetation has altered species com-
Forexample, in heathland in the UK, weed position compared with unslashed forest
invasion potential increased with the vegetation, though some vegetation com-
degree ofedge disturbance (Angold 1997). munities within the defined management
The heathy understorey vegetation in this zone, such as Wet Heath, largely escape
section ofthe Bunyip powerline easement treatment and consequently show few
was remarkably weed-free. This may be changes to structure or composition. At a
the result ofthe use ofslashing and selec- regional level,plant species diversity is not
The Victorian Naturalist
36
' . .
Research reports
reduced, and at the local level, overall movementsandmortalityofrainforestvertebrates.In
Tropical Rainforest Remnants: Ecology,
species diversity has increased as suitable Management, and Conservation ofFragmented
establishment sites were created for non- Communities Eds WF Laurance and RO
dfeonrseisttypilnanthtesepaesceimeesn.tHailgsohearppveaergsettaotciroen- GosBoimsearelrmleg-amMaarmda.mnad(lUnMicavoremrsmshiutnIyIiot(fy1C9hb9iy7c)aagFporoaPwgremereslnsi:tnaCethiicoconrargoiodf)oar
ate small mammal habitat, and the Wet through tropical rainforest. WildlifeResearch 24,
mHeenatthcoirnriddroarisnaacgreoslsintehsepcraosveimednets.mTohveer-e Hila6l1n3dD-Hc6a2.u9s.CeasnohfarmesCisDtanacnedtoWotroeediDnvMasi(o1n99i5n)riPgahtttse-ronfs-
was no indication that the powerline ease- way.EcologicalApplications5,459-470.
ment facilitated weed invasion. Vegetation HughesL.andWeslobyM(1992)Fateofseedsadapted
management by repeated slashing and tar- tfioorn.diEscpeorlsoaglyb7y3,an1t2s8i5n-1A2u9st9r.aliansclerophyllvegeta-
geted herbicide application under the Kershaw AK and Looney JH (1985) Quantitativeand
Bunyip State Park powerline easement at Dynamic PlantEcology 3rd ed. (Edward Arnold:
Melbourne)
this location has altered the vegetation, but Knight RE, Knight HAL and Camp RJ (1995)
does not appear to have had adverse con- Common ravens and number and type oflinear
servation impacts on local plant and small Krroigohdtss-moaf-wRaLy.(B1i9o8lo2g)icBailrCdoncsoemrmvautniiotny74e,c6o5l-o6g7y. on
mammal diversity. power-line corridors in East Tennessee. Biological
Conservation23,79-94.
Acknowledgements Lindenmeyer DB, Cunningham KB, Donnelly CF,
Data collection was carried out under Permit Trigg,sBEandBelvedereM(1994)Factorsinfluenc-
Number 10002025. We thank Dr. Dianne ing tlie occurrence ofmammals in retained linear
aDSneiaamlkmysioinnss,,UanniSdvcehfroosoriltcyoo,mfmfEeocrnotlcsoognoydnuatcnhtedinmEgannvtuihsrecorniPmpAet.nTtN, LoVsmMnitoasrcdnnitpaoatsrlgaiee(anw,mWeielsMndoaltusithafh6ne7edf,acosoLrt1reae1rsnr3itn-ed1oi3AArnu3sMs.)ttrha(aenl1id9ca9.e4cn)oFtnorTtraoieulgsruithosiEutgcsvhoellshotaigancnydld’esssanoaodsff
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Vol. 123 (1) 2006 37