5
salvaged material) or timing of works to simplify installa- tion of wood piles (e.g. possibly introduce CWD prior to planting to enable machinery to be used). Acknowledgements This project was conducted with the support of funding from the Australian Government’s Caring for Our Country program to the Wet Tropics Management Authority titled ‘Making Connections’ and the National Environmental Research Program (Tropical Ecosystems and Environmen- tal Decisions Hubs). We would like to thank Dave Hud- son, Carolyn Emms, Angela and Mark McCaffrey for generously allowing access to their properties and willing- ness to engage in this experimental restoration trial. Alice Crabtree and the team at Conservation Volunteers Austra- lia were integral to the installation of experimental trials. Deb Pople, Max Chappell and Campbell Clarke helped administer the project. Kylie Freebody, Graham Harring- ton and Amelia Elgar helped either in the field or contrib- uted resources to this project. References Barclay S., Ash J. E. and Rowell D. M. (2000) Environmental factors influenc- ing the presence and abundance of a log-dwelling invertebrate, Euperi- patoides rowelli (Onychophora: Peripatopsidae). Journal of Zoology 250, 425436. Catterall C. P., Kanowski J. and Wardell-Johnson J. (2008) Biodiversity and new forests: interacting processes, prospects and pitfalls of rainforest restoration. In: Living in a Dynamic Tropical Forest Landscape (eds N. Stork and S. Turton) pp. 510525. Wiley-Blackwell, Oxford. Freebody K. (2007) Rainforest revegetation in the uplands of the Australian Wet Tropics: planting models and monitoring requirements. Ecological Management and Restoration 8, 140143. Gibb H., Durant B. and Cunningham S. A. (2012) Arthropod colonisation of natural and experimental logs in an agricultural landscape: effects of habitat, isolation, season and exposure time. Ecological Management & Restoration 13, 166174. Grove S. J. (2001) Extent and composition of dead wood in Australian low- land tropical rainforest with different management histories. Forest Ecol- ogy and Management 154, 3553. Grove S. J. and Tucker N. I. J. (2000) Importance of mature timber habitat in forest management and restoration: what can insects tell us? Ecological Management and Restoration 1, 6264. Kanowski J. J., Reis T. M., Catterall C. P. and Piper S. D. (2006) Factors affecting the use of reforested sites by reptiles in cleared rainforest land- scapes in tropical and subtropical Australia. Restoration Ecology 14, 6776. Lindenmayer D. B., Claridge A. W., Gilmore A. M., Michael D. and Lindenma- yer B. D. (2002) The ecological role of logs in Australian forests and the potential impacts of harvesting intensification on log-using biota. Pacific Conservation Biology 8, 121140. Mac Nally R., Horrocks G. and Pettifer L. (2002) Experimental evidence for potential beneficial effects of fallen timber in forests. Ecological Applica- tions 12, 15881594. Manning A. D., Cunningham R. B. and Lindenmayer D. B. (2013) Bringing forward the benefits of coarse woody debris in ecosystem recovery under different levels of grazing and vegetation density. Biological Con- servation 157, 204214. Riffell S., Verschuyl J., Miller D. and Wigley T. B. (2011) Biofuel harvests, coarse woody debris, and biodiversity - A meta-analysis. Forest Ecology and Management 261, 878887. Wanger T. C., Saro A., Iskandar D. T. et al. (2009) Conservation value of cacao agroforestry for amphibians and reptiles in South-East Asia: com- bining correlative models with follow-up field experiments. Journal of Applied Ecology 46, 823832. Supporting Information Additional Supporting Information may be found in the online version of this article: Figure S1. Experimental design of coarse woody debris manipulation for a single site. CF - unmanipulated ground in forest; R - woody debris removed; CR - unmanipulated ground in restoration planting; L - salvaged log pile; P - fence post pile; and, M - supplementary salvaged log pile for microclimate monitoring. Figure S2. Experimental treatments in restoration plant- ings: control (top); salvaged fence post pile (middle); and salvage log pile (bottom). Do arbuscular mycorrhizal fungi recolonize revegetated grasslands? Paul Gibson-Roy 1,2 , Cass McLean 2 , John C. Delpratt 2 and Greg Moore 2 ( 1 Greening Australia, Level 1, 1 Smail St, PO Box 59, Broadway, NSW, 2007, Australia; Email: pgibson- [email protected]; 2 Department of Resource Management and Geography, Melbourne School of Land and Environment, The University of Melbourne, Burnley Campus, 500 Yarra Boulevard, Richmond, VIC, 3121, Australia). Key words: arbuscular mycorrhizal fungi, ecological restoration, grasslands, grassy woodlands, revegetation. Summary Fifteen native and common exotic herbaceous species from four functional groups (C4 grass, C3 grass, chamae- phyte and hemicryptophyte) occurring within remnant and revegetated grassland and grassy woodlands were sampled for evidence of structures associated with func- tioning arbuscular mycorrhizal fungi (AMF) from across a broad geographical range of central and south-western Victoria, Australia. Revegetated communities had been established on ex-agricultural land by direct seeding. They included sites that had been kept fallow with herbicide for up to 3 years prior to seeding and those from which top- soil had been removed (scalped) to a depth of 100 mm prior to seeding. Structures associated with AMF (external and internal aseptate hyphae, arbuscules and vesicles) were observed in root samples from all native and exotic SHORT REPORTS ª 2014 Ecological Society of Australia ECOLOGICAL MANAGEMENT & RESTORATION VOL 15 NO 1 JANUARY 2014 87 Ecological Society of Australia

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Page 1: Do arbuscular mycorrhizal fungi recolonize revegetated grasslands?

salvaged material) or timing of works to simplify installa-tion of wood piles (e.g. possibly introduce CWD prior toplanting to enable machinery to be used).

AcknowledgementsThis project was conducted with the support of fundingfrom the Australian Government’s Caring for Our Countryprogram to the Wet Tropics Management Authority titled‘Making Connections’ and the National EnvironmentalResearch Program (Tropical Ecosystems and Environmen-tal Decisions Hubs). We would like to thank Dave Hud-son, Carolyn Emms, Angela and Mark McCaffrey forgenerously allowing access to their properties and willing-ness to engage in this experimental restoration trial. AliceCrabtree and the team at Conservation Volunteers Austra-lia were integral to the installation of experimental trials.Deb Pople, Max Chappell and Campbell Clarke helpedadminister the project. Kylie Freebody, Graham Harring-ton and Amelia Elgar helped either in the field or contrib-uted resources to this project.

ReferencesBarclay S., Ash J. E. and Rowell D. M. (2000) Environmental factors influenc-

ing the presence and abundance of a log-dwelling invertebrate, Euperi-patoides rowelli (Onychophora: Peripatopsidae). Journal of Zoology250, 425–436.

Catterall C. P., Kanowski J. and Wardell-Johnson J. (2008) Biodiversity andnew forests: interacting processes, prospects and pitfalls of rainforestrestoration. In: Living in a Dynamic Tropical Forest Landscape (eds N.Stork and S. Turton) pp. 510–525. Wiley-Blackwell, Oxford.

Freebody K. (2007) Rainforest revegetation in the uplands of the AustralianWet Tropics: planting models and monitoring requirements. EcologicalManagement and Restoration 8, 140–143.

Gibb H., Durant B. and Cunningham S. A. (2012) Arthropod colonisation ofnatural and experimental logs in an agricultural landscape: effects ofhabitat, isolation, season and exposure time. Ecological Management& Restoration 13, 166–174.

Grove S. J. (2001) Extent and composition of dead wood in Australian low-land tropical rainforest with different management histories. Forest Ecol-ogy and Management 154, 35–53.

Grove S. J. and Tucker N. I. J. (2000) Importance of mature timber habitat inforest management and restoration: what can insects tell us? EcologicalManagement and Restoration 1, 62–64.

Kanowski J. J., Reis T. M., Catterall C. P. and Piper S. D. (2006) Factorsaffecting the use of reforested sites by reptiles in cleared rainforest land-scapes in tropical and subtropical Australia. Restoration Ecology 14, 67–76.

Lindenmayer D. B., Claridge A. W., Gilmore A. M., Michael D. and Lindenma-yer B. D. (2002) The ecological role of logs in Australian forests and thepotential impacts of harvesting intensification on log-using biota. PacificConservation Biology 8, 121–140.

Mac Nally R., Horrocks G. and Pettifer L. (2002) Experimental evidence forpotential beneficial effects of fallen timber in forests. Ecological Applica-tions 12, 1588–1594.

Manning A. D., Cunningham R. B. and Lindenmayer D. B. (2013) Bringingforward the benefits of coarse woody debris in ecosystem recoveryunder different levels of grazing and vegetation density. Biological Con-servation 157, 204–214.

Riffell S., Verschuyl J., Miller D. and Wigley T. B. (2011) Biofuel harvests,coarse woody debris, and biodiversity - A meta-analysis. Forest Ecologyand Management 261, 878–887.

Wanger T. C., Saro A., Iskandar D. T. et al. (2009) Conservation value ofcacao agroforestry for amphibians and reptiles in South-East Asia: com-bining correlative models with follow-up field experiments. Journal ofApplied Ecology 46, 823–832.

Supporting Information

Additional Supporting Information may be found in theonline version of this article:Figure S1. Experimental design of coarse woody debrismanipulation for a single site. CF - unmanipulated groundin forest; R - woody debris removed; CR - unmanipulatedground in restoration planting; L - salvaged log pile; P -fence post pile; and, M - supplementary salvaged log pilefor microclimate monitoring.

Figure S2. Experimental treatments in restoration plant-ings: control (top); salvaged fence post pile (middle);and salvage log pile (bottom).

Do arbuscular mycorrhizalfungi recolonize revegetatedgrasslands?

Paul Gibson-Roy1,2, Cass McLean2, John C. Delpratt2 andGreg Moore2 (1Greening Australia, Level 1, 1 Smail St, POBox 59, Broadway, NSW, 2007, Australia; Email: [email protected]; 2Department of ResourceManagement and Geography, Melbourne School of Landand Environment, The University of Melbourne, BurnleyCampus, 500 Yarra Boulevard, Richmond, VIC, 3121,Australia).

Key words: arbuscular mycorrhizal fungi, ecologicalrestoration, grasslands, grassy woodlands, revegetation.

SummaryFifteen native and common exotic herbaceous speciesfrom four functional groups (C4 grass, C3 grass, chamae-phyte and hemicryptophyte) occurring within remnantand revegetated grassland and grassy woodlands weresampled for evidence of structures associated with func-tioning arbuscular mycorrhizal fungi (AMF) from acrossa broad geographical range of central and south-westernVictoria, Australia. Revegetated communities had beenestablished on ex-agricultural land by direct seeding. Theyincluded sites that had been kept fallow with herbicide forup to 3 years prior to seeding and those from which top-soil had been removed (scalped) to a depth of 100 mmprior to seeding. Structures associated with AMF (externaland internal aseptate hyphae, arbuscules and vesicles)were observed in root samples from all native and exotic

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species, regardless of site history (remnant or revegetated;fallowed or scalped). These findings indicate that AMF areubiquitous in the herbaceous flora of this region (nativeand exotic), even in situations where sites had been inten-sively disturbed prior to revegetation treatment. However,while there was evidence of AMF in all revegetated com-munities, only sites which had been scalped prior to directseeding supported species-rich native herbaceous com-munities.

IntroductionArbuscular mycorrhizal fungi (AMF) have been found inassociation with most vascular plant species studied (e.g.Brundrett 2009), and associations in herbaceous communi-ties in the UK and North America have been widelyreported (Gibson 2009). Worldwide, AMF are also knownto be important components of herbaceous agriculturalsystems (e.g. Tibbett et al. 2008; Muchane et al. 2012). InAustralia, AMF are reported as the most common andwidespread subterranean symbionts occurring in a widerange of natural habitats, including herbaceous communi-ties (McGee 1986).

Plant roots infected by AMF exhibit certain structuresthat indicate a functioning, mutualistic relationship (Smith& Read 2008; Brundrett 2009). These include external andinternal hyphae, arbuscules and vesicles, which support avariety of functions including nutrient acquisition andtransfer and carbohydrate storage. Hyphae connect thesoil environment and plant roots and are primarily withoutcross-walls (aseptate) although septae in hyphae mayincrease with age. Hyphae of AMF proliferate within thehost root cortex as two distinct morphological types, oneextending through intercellular spaces and the second asintracellular coils that extend from cell to cell. Arbusculesare the main site of nutrient exchange between fungus andhost, and develop as dichotomous branching or ‘treelike’structures. Vesicles are the primary site of storage of car-bon from the plant host and develop after the initiationof arbuscules (Smith & Read 2008).

Following European settlement and the adoption ofintensive agriculture in south-eastern Australia, there hasbeen a dramatic shift in the composition of the herbaceousflora with a large-scale reduction in the range and diversityof native herbaceous communities (grasslands and grassywoodlands) and an associated increase in the range anddominance of exotic herbaceous species (ruderal andperennial). This has left native grasslands and grassy wood-lands amongAustralia’s most threatened plant communities(Kirkpatrick et al. 1995). Regardless of the composition ofthe herbaceous community, studies have shown that activ-ities associated with the types of agriculture undertaken inthis region (such as prolonged soil disturbance – cultiva-tion, compaction, movement, fertilization and extendedfallowing) can adversely affect AMF communities and indi-

rectly reduce the capacity of their native or exotic planthosts to compete (Smith & Read 2008).

Due to the scale of decline of native south-eastern Aus-tralian herbaceous communities, ecological restoration isnow viewed as an increasingly important factor in theirlong-term preservation (Lunt et al. 2010). The most com-mon outcome of unsuccessful revegetation is poor or nilestablishment of target native species, and an associateddomination by nondesired exotic species. The widespreadoccurrence of exotic species in these landscapes meansthat invasion and competition is predictable when theyare favoured by increased soil nutrients (Dorrough &Scroggie 2008). A range of site preparation methods aimto ameliorate these factors. Techniques include long-termfallowing to exhaust soil weed seed banks (herbicideapplication combined with cultivation), and topsoilremoval (scalping) to reduce weed seed and bud banks,and remove nutrient enriched soil strata (Gibson-Roy et al.2010a,b). A concern is that these techniques may nega-tively impact on mycorrhizae and their associated benefitsfor the revegetated community (Muchane et al. 2012).

While some studies suggest that revegetated communi-ties are diminished in plant and animal diversity in com-parison with intact remnant communities (e.g. Barrettet al. 2009), others report that over time, revegetated com-munities can re-establish trophic complexity, includingmycorrhizal associations. Examples include highly dis-turbed locations such as rehabilitated mine sites (Chenet al. 2007, Sheoran et al. 2010) and agricultural land-scapes (Haug et al. 2010).

This study reports on the AMF colonization characteris-tics of native and exotic species in remnant and revegetat-ed herbaceous communities within agricultural landscapesof central and south-western Victoria, Australia and com-pares these characteristics between remnant and revegetat-ed sites including those that were subjected to differingweed and soil management actions prior to direct seeding.

MethodsPlant species selection for this study targeted representa-tives of four commonly described functional groups withinherbaceous communities: C4 grass, C3 grass, chamaephyteand hemicryptophyte (e.g. Gibson-Roy et al. 2010a,b).Twelve native species and three exotic species (based oncommon occurrence in rural landscapes) were targeted(Table 1). Target species occurred at locations throughoutthe south-west and central regions of Victoria, spanningfour Catchment Management regions (Corangamite, Gle-nelg-Hopkins, North Central and Port Philip/WesternPort). Sampled populations (each separated by >100 km)occurred in four existing grassland or grassy woodlandremnants (in the regions of Craigieburn, Hamilton, Ravens-wood and Shelford/Cressy) and from six communities thathad been direct seeded onto bare-field sites (in the regions

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of Hamilton, Ravenswood and Shelford/Cressy). One rev-egetated community from each of these three regions hadbeen kept fallow with herbicide for up to 3 years prior toseeding, and one from each region had topsoil removed(scalped) to a depth of 100 mm prior to seeding (Gib-son-Roy et al. 2010a,b). Plant populations occurring onthe revegetated sites had been established for between18 months and 3 years at the time of fungal surveys.

Sampling was conducted during periods of active plantgrowth (spring and autumn). Root cores were removedfrom the base of a minimum of 20 plants of each speciesat each of the 10 sites, using a sharpened stainless steel tube.Each core was examined to ensure they contained fine rootsfrom the targeted individual in appropriate quantities forassessment. Samples for each species were taken fromplants occurring not closer than 2 m from another individualof that species and within 10 m either side of transect lines.Root samples were stored in 70% ethanol in individualsealed and labelled vials until processing and analysis.

Roots were cleared and stained using the technique ofSmith and Dickson (1995) as modified by McLean and Law-

rie (1996). Multiple fine root segments were assessed fromeach sample under a compound light microscope (NikonEclipse E400, Nikon Corporation, Yokohama, Japan) overa range of magnifications (1009, 2009, 4009 and10009). Samples were assessed for the presence/absenceof structures which included external and internal aseptatehyphae, arbuscules and vesicles as key criteria for the diag-nosis of AM (McLean et al. 1999; Brundrett 2009). The pres-ence of dark septate internal hyphae was also noted. Theproportion of root length colonized by AMF was estimatedusing grid intersect (Smith & Dickson 1995) and compoundmicroscope slide assessment (McGonigle et al. 1990).

Differences in percentage root colonization were analy-sed within (not between) each species across locationsand/or site preparation histories. Data were comparedusing ANOVAs, using the statistical software Minitab 16.1(Minitab Inc. State College, PA, USA).

ResultsStructures indicating the presence of functioning AMF,including aseptate external hyphae and internal hyphae,

Table 1. Percentage root colonization of twelve native and three exotic grassland species sampled from remnant and revegetated sites in south-

western and central Victoria. Species, family and functional group designations, sampling locations and descriptions, percentage root colonization (as

per McGonigle et al. 1990) and history of sampled location.

Species Family Functionalgroup

Location % Root colonization

Remnant Scalp &seeded

Fallow &seeded

Austrostipa bigeniculata Poaceae C3 Grass H 56a 51a 47aAustrostipa mollis Poaceae C3 Grass R 62a 55a 48aAustrostipa scabra Poaceae C3 Grass S/Cr 53a

R 52a 50aCalocephalus citreus Asteraceae Hemicryptophyte H 56a

S/Cr 63aChloris truncata Poaceae C4 Grass R 82a 80a

S/Cr 75aChrysocephalum apiculatum Asteraceae Hemicryptophyte H 30a 37a 27a

S/Cr 33aHypochoeris radicata* Asteraceae Hemicryptophyte R 54a 59a

S/Cr 46aLeptorhynchos squamatus Asteraceae Hemicryptophyte H 31a

S/Cr 30aLolium perenne* Poaceae C3 Grass R 60a

S/Cr 60aPhalaris aquatica* Poaceae C3 Grass H 53a

R 60aS/Cr 60a

Rytidosperma caespitosum Poaceae C3 Grass H 43a 59a 53aRytidosperma racemosum Poaceae C3 Grass H 46a 56a 43aRytidosperma setaceum Poaceae C3 Grass H 49a 55a 44aThemeda triandra Poaceae C4 Grass C 81a

H 53b 48b 38bS/Cr 57a

Xerochrysum bracteatum Asteraceae Chamaephyte R 43a 36a

Significant differences (a/b) at P < 0.05 based on comparisons of % root colonization within each species between sampled locations (not betweenspecies). *denotes exotic species. Location description: remnant grassland, scalped and seeded grassland and fallow and seeded grassland.Assessment of arbuscular mycorrhizal fungi status based on observations of arbuscules, hyphae (external/internal) and vesicles (as per Brundrett2009). Plant nomenclature according to Walsh and Stajsic (2007) and Linder et al. (2010). Location: C, Craigieburn Grassland Reserve; H,Department of Primary Industries research property Hamilton; R, Ravenswood; S/Cr, Shelford/Cressy.

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arbuscules and vesicleswere observed in root samples fromall twelve native and the three exotic species (Table 1). Thiswas regardless of whether plants occurred in remnant orrevegetated communities or from revegetated sites with dif-ferent preparation histories (fallowed or scalped).

Only kangaroo grass (Themeda triandra) exhibited asignificant statistical difference in the percentage rootcolonization between samples from different locations,with samples from two of three remnant grasslands exhib-iting significantly higher percentage colonization thanthose sampled from one other remnant and both revege-tated sites (Table 1). Despite a lack of significant statisticaldifference, all other species displayed varying root AMFcolonization patterns (from medium: 11–49% to very high:>80%) between and within species and sites. Of the 15species examined, six exhibited a consistently similar col-onization range across all sites and histories, with fourshowing high levels of colonization (rough spear grass –Austrostipa scabra, lemon beauty heads – Calocephaluscitreus, perennial rye grass – Lolium perenne* and phalaris– Phalaris aquatic*) and two medium levels of coloniza-tion (common everlasting – Chrysocephalum apiculatumand scaly buttons – Leptorhynchos squamatus).

Intercellular hyphae were the most frequently observedstructures, with vesicles then arbuscules observed to lesserdegrees, satisfying the criteria for diagnosis of AMF(Brundrett 2009). Dark septate hyphae were also notedin all species, but at low frequency. Differences in vesiclemorphology were noted, with most observed as large,thick-walled and rounded structures.

DiscussionEstablishing diverse, functioning native plant communi-ties, which are not dominated by exotic species, is the pri-mary goal of ecological restoration. However, it iscommon for invading herbaceous weeds or those originat-ing from soil seed and bud banks to dominate and elimi-nate such communities, particularly when topsoilcontains increased levels of nitrogen and phosphorus(Dorrough & Scroggie 2008). Recent research has com-pared the efficacy of long-term chemical fallowing andtopsoil scalping for weed control in multispecies sowingsof herbaceous native grasslands. Scalping of nutrient-and weed seed-rich topsoil was most effective in allowingthe establishment of diverse grassland communities bydirect seeding (Gibson-Roy et al. 2010a,b). However, suchdrastic soil modification may disrupt or remove criticalcomponents of the rhizosphere such as arbuscular mycor-rhizal fungi (Smith & Read 2008), possibly threatening theresilience and longer-term persistence of the revegetatedcommunities.

This study found evidence of AMF in all twelve nativeand three exotic species sampled. While this may havebeen predicted from the broader mycorrhizal literature

(e.g. Brundrett 2009), it suggests that they are ubiquitousin these south-eastern Australian herbaceous landscapes(whether dominated by native or exotic species). Of par-ticular interest is the occurrence of AMF in revegetatedcommunities with very different site preparation histories.Here, it is likely that hyphal, spore and/or colonized rootfragments remaining in the soils, or which had movedonto the sites following seeding through wind, waterand soil, or animal movement had provided the inoculumfor colonization of the establishing plant communities.These observations also suggest that AMF colonization islikely to follow soil disturbance from other environmentalevents such as fires and floods, or when vegetation isrevegetated following disturbances such as road works.

With the exception of kangaroo grass, percentage rootcolonization for species from revegetated sites was not sig-nificantly different from those from remnant sites. Even forkangaroo grass, colonization did not fall below the med-ium level in revegetated vegetation. Root colonization lev-els were not statistically significant different betweenscalped and fallowed restoration sites despite plant sur-veys (Gibson-Roy et al. 2010b, Gibson-Roy 2011, unpub-lished), indicating that scalped sites contained highernumbers, densities and cover of native species while fal-lowed sites contained higher numbers, densities and coverof exotic species. This suggests that while site preparationmethods had a marked impact on the vegetation structure,they had little impact on eventual AMF colonization.

Associations between exotic species and AMF havebeen reported in species that coexist with natives in Aus-tralian agricultural pasture systems (e.g. Tibbett et al.2008). The three perennial weeds sampled in this study,yellow catsear (Hypochoeris radicata), rye grass and pha-laris, all hosted mycorrhizal associations as reported inother studies (e.g. Guo et al. 2012). Each species is a fre-quent component of pasture systems, rural roadside vege-tation and within remnant communities of south-easternAustralia. In the latter, they are viewed as undesirablebecause they compete strongly against subdominantnative grasses and herbs (in particular, phalaris). It is likelythat each derives some competitive advantage from theAM association, and with co-occurring mycorrhizal nativespecies, forms part of a larger interspecific resource flowin those communities (Smith & Read 2008).

Implications for AMF in reconstructed herbaceouscommunities

Native herbaceous communities remain critically endan-gered in south-eastern Australia. Recent research has pro-vided encouraging evidence that diverse native perennialcommunities can be reconstructed by revegetation whennutrients and weed loads are sufficiently reduced. Oneof the most direct and effective methods for achievingthese joint requirements is topsoil scalping. Although the

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process appears drastic, it is reassuring that AMF areobserved in the revegetated vegetation.

AcknowledgementDedicated to the memory of Dr Cass McLean who inspiredstudents and colleagues alike. Authors thank ProfessorWal Whalley for his valued support and comments.

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Mortality of native grassesafter a summer fire in naturaltemperate grassland suggestsecosystem instability

Steve J. Sinclair1, David H. Duncan2 and Matthew J.Bruce1,3 (1Arthur Rylah Institute for EnvironmentalResearch, Department of Environment and PrimaryIndustries, 123 Brown Street, Heidelberg, Vic. 3084,Australia; Email: [email protected]; 2NERPEnvironmental DecisionsHub, School of Botany, Universityof Melbourne, Parkville, Vic. 3010, Australia;3School of Life Sciences, La Trobe University, Bundoora,Vic. 3086, Australia).

Key words: natural temperate grassland of the Victorianvolcanic plains, stable states, transition.

SummaryThe exclusion of regular fire and the introduction oflivestock grazing have altered native grassland composi-tion on Victoria’s volcanic plains, commonly resultingin spear-grass and wallaby-grass pastures replacingKangaroo Grass grasslands. The effect of reintroducingfire to these pastures is currently unknown, although itmay be an important part of restoring this ecosystem.We measured the changes in basal area of the dominantgrasses in a mixed Spear-grass/Wallaby-grass pasturesafter a summer wildfire, which we assume burnt arelatively homogenous grass sward. We found a90–95% reduction in the basal area of live spear-grasstussocks in burnt plots compared with unburnedcontrols, due to the mortality of tussocks. This suggeststhat caution and structured experimentation shouldbe applied when using fire to manage spear-grass-dominated grasslands.

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ª 2014 Ecological Society of Australia ECOLOGICAL MANAGEMENT & RESTORATION VOL 15 NO 1 JANUARY 2014 91