The East Gippsland Silvicultural Systems Project. II: Germination and early survival of eucalypt...

167Ross Squire, Peter Geary and Mark Lutze

Australian Forestry 2006 Vol. 69 No. 3 pp. 167–181

The East Gippsland Silvicultural Systems Project.I: The establishment of the project in lowland forest

Ross Squire1,2,3, Peter Geary1 and Mark Lutze1,3

1Lands and Forests Division, Department of Conservation and Environment, 240 Victoria Parade,East Melbourne, Victoria 3002, Australia

2Email: [email protected] address: C/- Simon Murphy, School of Forest and Ecosystem Science, The University of Melbourne,

Water St, Creswick, Victoria 3363, Australia

Revised manuscript received 9 January 2006

Summary

The Silvicultural Systems Project (SSP) was established inVictoria, Australia, to test the major hypothesis that a betterbalance between economic and environmental concerns in nativeforest being managed for sustainable wood production can beachieved by systems other than clearfelling. The primary earlyfocus of SSP was on two forest types representing much of thisforest, that is, the mountain ash forests of central and southernVictoria, and the lowland forests of mixed eucalypt species inthe coastal belt of East Gippsland. Phase 1 of SSP was implementedon an experimental coupe scale, comparing a range of silviculturaltreatments for occupational health and safety, particularly duringharvesting, and for eucalypt regeneration, including seed supply,and growth. Data on harvesting and regeneration costs were alsocollected.

This paper describes the location, climate, geology and soils,topography, fire history, vegetation and pre-harvesting timberresources of the 580-ha SSP site in East Gippsland. It alsodescribes the experimental design, planning, prescriptions,implementation and outcomes of the treatments.

The treatments included nine harvesting treatments representingpoints along two continua, one of increasing gap size and theother of decreasing overwood retention. Unharvested forestrepresented the starting point for both continua, that is, a 0-hagap and 100% overwood retention. Harvesting treatments werecombined with site preparation by fire and by mechanicaldisturbance, and treatment combinations were replicated two tofour times in space and over two years (1989 and 1990). Thestudies involved the establishment and monitoring of treatmentson a total of 94 coupes of a range of sizes.

Keywords: silvicultural systems; clearcutting; shelterwood system;safety; harvesting; regeneration; seed sources; site preparation; fire;Eucalyptus; Victoria

Introduction

This paper describes the establishment and initial monitoring ofan experimental forest near Cabbage Tree Creek (Cabbage Tree)in East Gippsland, Victoria, by the Department of Sustainability

and Environment (DSE)*. The experiment is part of a compre-hensive long-term research and development program termedthe Silvicultural Systems Project (SSP). SSP arose out of con-troversy over use of the clearfelling (clearfell) silvicultural systemfor sustainable wood production from the native State forests ofVictoria (Government of Victoria 1986; Squire 1987, 1990).

A silvicultural investigation of the magnitude of SSP has neverbefore been implemented in Australia. There have been smallerinvestigations of the effects of a limited range of harvesting andsite preparation treatments (e.g. Abbott and Lonergan 1984;Battaglia and Wilson 1990; Kellas 1994). Since the commence-ment of SSP a number of experiments have been established inTasmania with similar objectives to Phase 1 of SSP, but the rangeof treatments and replication has been less (e.g. Neyland et al.1999; Bassett et al. 2000; Hickey et al. 2001). Numerousexperiments with similar objectives have been established in thenative forests of North America over the past decade (e.g.Holstedt and Vyse 1997; Marshall 1999). These developmentshighlight the importance of the SSP experiment for the long-term management of Victoria’s native State forests.

The clearfell silvicultural system has been developed and appliedover a range of forest types in Victoria. This system satisfies thebiological requirements for successful regeneration of thedominant eucalypts (Squire et al. 1991), and has a high degreeof operational efficiency (Ferguson 1985). There is, however,considerable concern over its use, especially on environmentalgrounds. Indeed, there is concern within some sections of thecommunity over whether or not native forests should be used forwood production at all. Nevertheless, successive Victorian

*The nomenclature of the responsible department has changed a number of timesin the course of this work. The affiliation of authors in this and the two followingassociated papers is recorded as at the time of preparation of the manuscripts. Keynames in chronological order are:

• Lands and Forests Division, Department of Conservation and Environment

• Forest Research and Development Branch, Department of Conservationand Natural Resources

• Forests Service, Department of Natural Resources and Environment

• Department of Sustainability and Environment.

168 SSP I: Establishment


Governments have accepted, albeit with tight controls, that woodproduction is an integral part of the management of the State’snative forests, starting with the publication of a Timber IndustryStrategy (Government of Victoria 1986) and continuing to thepresent via the Regional Forest Agreement (RFA) process(Commonwealth of Australia 2000).

Objective and methods

The broad objective of SSP, within the above policy framework,is to evaluate and, where appropriate, develop alternative systemsto clearfell for sustainable wood production within native forests.The major hypothesis is that a better balance between economicand environmental concerns can be achieved by systems otherthan clearfelling. Squire (1987) discussed and made recommenda-tions on the silvicultural systems to be tested, and the design andimplementation of the field experiments. The main SSPhypothesis was to be tested in two phases that differed in scaleand emphasis. Phase1 was to be implemented on an experimentalscale to compare silvicultural systems for occupational healthand safety, particularly during harvesting, and for eucalyptregeneration and growth. Data on harvesting and regenerationcosts would also be collected in this phase. Phase 2 was to beimplemented on an operational scale, using systems identified inPhase 1 as successful for sustainable wood production, to comparethese systems using long-term studies into basic ecologicalprocesses (flora, fauna, soils, water, etc.) and the construction ofsimulation models (ecological, management and socio-economic).

The silvicultural systems evaluated in Phase 1 include clearfell,seedtree, shelterwood and gap selection and, for each, twomethods of seedbed preparation, namely, mechanical disturbanceand fire. In a classical sense, silvicultural systems for sustainedwood production are usually named in a manner that describesthe spatial and temporal distribution of tree removal (e.g. theselection and shelterwood systems) (Squire 1990). However,spatial, cost and time constraints precluded an evaluation in this

way in Phase 1. Therefore, for the Phase 1 evaluation, a silvi-cultural system was related to the size of canopy opening(selection to clearfelling systems) or the basal area of the retainedtrees (shelterwood, seedtree spatial, clearfelling systems).

The primary focus of SSP during its early development was ontwo forest types representing much of the native forest beingmanaged for sustainable wood production. These are the mountainash (Eucalyptus regnans) forests of central and southern Victoria(Campbell 1997a,b), and the lowland forests (formerly LowlandSclerophyll Forest, see Woodgate et al. 1994) of mixed eucalyptspecies in the coastal belt of East Gippsland. High-ElevationMixed-Species (HEMS) forest was initially chosen as the mostimportant forest type for study in East Gippsland, and a pilottrial was undertaken to give the Department, and industry,experience with the harvesting treatments proposed for evaluationin the main experiment.

The main purpose of this paper is to describe the site, theexperimental design, and the design of specific studies in thelowland forest of East Gippsland. Germination and early survivalof eucalypt regeneration is described by Faunt et al. (2006), anddevelopment to age 12 y by Lutze and Faunt (2006).

Pilot trial

The pilot trial was implemented early in 1987 in HEMS forest atBrown Mountain, 6 km SSE of Bonang, in the Brodribb ForestManagement Block of the Orbost Region (Fig. 1). Clearfell withseed tree retention, shelterwood, and small and large groupselection harvesting were tested in the pilot trial, which wasfollowed by routine harvesting and regeneration operations. Themost important findings concerned occupational health and safety.Given then-current technology and procedures, the alternativesystems had a substantially greater safety hazard compared tothe existing clearfell system.

Figure 1. Location of the Silvicultural Systems Project experiment site near Cabbage Tree Creek and Bonang in East Gippsland, Victoria

ORBOSTCabbage Tree Creek

Cann River

Western

Australia

Northern

Territory

South

Australia

Queensland

New South

Wales

ACTVictoria

East

Gippsland

Tasmania

N

Scale

0 10 20 30 km

Location of East Gippsland

Site

Bonang

State boundary Major road Stream

Site

https://www.researchgate.net/publication/267792186_The_East_Gippsland_Silvicultural_Systems_Project_II_Germination_and_early_survival_of_eucalypt_regeneration?el=1_x_8&enrichId=rgreq-ed8e26d7-3755-49ee-875e-a38b30caf464&enrichSource=Y292ZXJQYWdlOzIyODYxNTk2OTtBUzoxODcxMDQ4NjA1ODE4ODhAMTQyMTYyMDY4MzI2MA==



However, the HEMS forest assumed decreasing importance as atimber resource as National Park and National Estate considera-tions reduced the area of State forests available for woodproduction. Subsequently, the Cabbage Tree site, in the CabbageTree Creek Management Block of the Orbost Region, wasselected in lowland forest that, by default, had increasedconsiderably in importance as a timber resource.

The site

Locality and size

Stuwe and Mueck (1990) described most of the Cabbage Treesite in some detail. However, their work predated amendmentsto the boundaries made during the establishment of the experimentand which were, in part, in response to their work. In its finalconfiguration, the gross area of the site was about 580 ha. Itscentre was about 3 km north-east of Cabbage Tree Creek townshipand about 13 km inland from the coast (Fig. 1).

A 100 m × 100 m grid, orientated at a primary compass bearingof 340°, was established across the entire area; grid points weremarked with numbered metal pegs and accurately mapped. Thesegrid points were used as reference points for the surveys thatformed the basis of the site description, and to facilitate accuratelocation of coupes and subsequent research within them.

Geology and soils

Geological maps of the East Gippsland region (Douglas 1976;Land Conservation Council 1985) depict the Cabbage Tree siteas consisting of Late Tertiary sediments (including marls, gravels,sandstones and sands) that may or may not have been weatheredto expose sections of the underlying, older geological material.Beams and Hough (1979) inspected part of the site and foundexposures of Cabbage Tree granodiorite, a coarse-grainedhornebende granodiorite, along Cabbage Tree Creek on thewestern edge of the site, and an adjoining smaller exposure ofKuark metamorphics, consisting of gneisses and schists formedfrom Lower Palaeozoic sediments.

With this background, Talsma and Platts (1988) conducted adetailed survey of the soils on the site and identified threeprincipal soil profile forms: gradational, duplex and uniform.Gradational soils were largely associated with the granodioriteand metamorphic exposures, but also occurred along lower slopesand gullies within the Tertiary sediments. These soils weredescribed as Yellow Earths (Gn 2.24) or Grey Earths (Gn 2.84),with loamy sand to clay loam A horizons, 30–60 cm thick, andloam to medium clay B horizons. Almost all of the duplex soilsfound were on the Tertiary sediments and, largely as an effect oflandscape position, were classified as either red (Dr) (plateauxand upper slope) or yellow (Dy) (mid- to lower slope), orsometimes brown (Db) podzols. A horizons varied from sandsto clay loams and from 30 cm to 100 cm in depth. B horizonswere generally clay loams to medium clays. All uniform, coarse-textured profiles (Uc) detected were also on the Tertiary sedi-ments, but largely on plateaux or adjacent gentle slopes. Theseprofiles generally consisted of leached sands, with dark organicmatter in their A1 horizons, bleached A2 horizons and anunderlying ‘coffee-rock’ hard pan. Depth to this pan was 35–115 cm,

with profiles in swales or depressions having pans at shallowerdepths. For some profiles, no hard pan was encountered to 1.2m, the maximum profile depth examined.

Talsma and Platts (1988) mapped the distribution of theseprincipal soil types over the site. However, like Stuwe and Mueck(1990), their work pre-dated some changes in site boundaries.Consequently, supplementary surveys were carried out(E. Stucken, formerly Department of Conservation and Environ-ment, pers. comm., 1994) to classify the soils in any areasadditional to those already examined.

Talsma and Platts (1988) reported that all soils on the site wereacid, with the coarse leached sands being most acid. Total nitrogen(N) and phosphorus (P) were low in all soils, a finding laterconfirmed by CSIRO (1991), who found total P to be extremelylow, with both nutrients at levels likely to be limiting for treegrowth. Both Talsma and Platts (1988) and CSIRO (1991) providefurther details on the chemical and physical properties of thesoils.

Topography and hydrology

In 1988, the Australian Centre for Catchment Hydrology, CSIRODivision of Water Resources, was commissioned to describe andmap the topographic and hydrologic characteristics of the SSPexperimental site at Cabbage Tree. A full account of themethodology and results is given in O’Loughlin et al. (1988).

Contours derived from Digital Terrain Mapping were used toprovide the basic input data for calculating the followingtopographic and hydrologic attributes for each of the severalthousands of computational elements into which the site wasdivided: slope, aspect, potential solar radiation and wetness index.

Topographic and hydrologic characteristics were described forsome 540 ha bounded by Winter Road, Emphields Track andFalls Creek Road No. 1. The attributes were presented as functionsmapped onto 1 : 5000 scale sheets, with a transparent overlay ofthe basic topography. Supplementary diagrams of smoothed andinterpolated attributes were also given at a scale of 1 :15 000.Altitude ranged from 70 m to 200 m above sea level and slopesfrom 0° to 20°, although most were less than 10°.

Climate

Climatic data relevant to the Cabbage Tree site were availablefrom Bureau of Meteorology weather stations at Cabbage TreeCreek (rainfall records from 1946) and Orbost (rainfall recordsfrom 1883 and temperature records from 1938), and weatherstations located at the site over the period September 1989 toJune 1994.

Lutze (1998b) used all three sources to summarise the meanmonthly minimum and maximum temperatures and monthlyrainfall at the Cabbage Tree site for the period October 1988 –June 1994 and to relate the temperature and rainfall patterns tolong-term averages and amounts over the same period at theBureau stations.

The analysis of Lutze (1998b) for the period October 1988 –June 1994 suggests that the data from the Bureau stations provide



a good indication of the likely long-term climate at the CabbageTree site. Average temperatures at the Cabbage Tree site wereabout 1–2°C lower than at Orbost station, and total rainfall about10% more than recorded at the Cabbage Tree Creek station. Thedifferences were consistent with the regional trend of decreasingtemperature and increasing rainfall with increasing altitude; thealtitude of the Cabbage Tree site is about 100 m higher thanOrbost and Cabbage Tree Creek. Thus the long-term recordssuggest that, for the Cabbage Tree site, rainfall will be dependable(1100 mm y–1 with an even distribution throughout the year),frosts infrequent (in the order of 30 y–1), and snowfalls rare (Stuweand Mueck 1990).

Vegetation

Stuwe and Mueck (1990) carried out a detailed quadrat-basedsurvey of the flora on the site prior to harvesting. One hundredand sixty-two quadrats (30 m × 30 m) on the 100 m × 100 m gridwere established and assessed before treatment (Stuwe and Mueck1990), and four sub-communities of Lowland Sclerophyll Forest(sub-communities 1.1 to 1.4) and one of Damp Sclerophyll Forest(sub-community 2.1) were identified (after Gullan et al. 1981).Hereafter, in accord with the work of Woodgate et al. (1994),these forest types will be referred to as Lowland Forest (LF) andDamp Forest (DF), respectively. Few species are frequentcomponents of both forest types present on the site. Distributionsderived from Stuwe and Mueck (1990) confirm that most of thesite is, as intended, typical LF, ‘the best represented’ (Forbes etal. 1982) or ‘most abundant’ (Land Conservation Council 1985;Stuwe and Mueck 1990) vegetation community in East Gippsland.

Incidence of Phytophthora cinnamomi

Phytophthora cinnamomi is a soil-borne fungus that is pathogenicto many plant species. It is known to be widely distributed in thecoastal forests of East Gippsland (Marks et al. 1975) and thecause of periodic severe die-back in those forests (Marks et al.1972). A detailed survey was carried out in January 1988, priorto harvesting, to determine the distribution of the fungus acrossthe site. Soil samples were collected from about 300 points acrossthe site and were tested for the presence of P. cinnamomi usingthe cotyledon baiting technique (Marks and Kassaby 1979). The

results indicated that the fungus occurs throughout the site,although it was noted that disease expression was mainly confinedto mature E. sieberi trees on slopes of less than 5° (I.W. Smith,forest pathologist, School of Forest and Ecosystem Science, pers.comm., 1994).

Fire and timber harvesting history

Most of the site, as described by Stuwe and Mueck (1990), hadno known history of timber harvesting prior to SSP, apart from asmall quantity of bed-logs felled for a bridge. However, the 60-ha section south of Falls Creek, which was added after Stuweand Mueck (1990) had completed their work, had been selectivelyfelled for railway sleepers and, possibly, sawlogs before 1970.

Records of the various responsible Departments indicate thefollowing fire history:

• the section south of Falls Creek had been burnt in 1962/63

• the entire site was burnt by a wildfire in 1967/68

• attempts were made in 1972/73 to carry out a fuel reductionburn in a small section in the north of the site, but the fire wasrecorded as being ineffective, with only 20% coverage

• most of the southern third of the site was burnt by a wildfire inOctober 1984; the bulldozer track used to control the fire isstill visible in the field.

Timber resources

Cumming and Black (1993) carried out a detailed pre-harvesttimber assessment of the Cabbage Tree site to obtain baselinedata on stand density, height, stem diameter, basal area, merchant-able volume and species composition. Coupe-level results areaddressed in more detail later (see pre-harvest timber assessment).Generally, the measurements of stand characteristics highlightedthe variability of the two forest types (i.e. LF and DF). Fortreatment means, basal areas were 29.4–43.5 m2 ha–1, standheights 33–39 m and total stocking (density) 114–613 trees ha–1

(Table 1). The large variation in stocking was attributed to thepresence of young regrowth on some coupes. Merchantablevolume was generally low, and species and product grades variedgreatly between coupes. The species composition of the forest

Table 1. Summary of stand characteristics and mean merchantable volume by harvesting treatments in the Silvicultural Systems Project experiment at Cabbage Tree Creek in East Gippsland, Victoria (Cumming and Black 1993)

Density (stems ha–1)

Basal area (m2 ha–1)

Mean merchantable volume (m3 ha–1)

Harvesting treatment Height

(m)

Trees >30 cm dbh

All trees

Trees >30 cm dbh

All trees

Sawlog RL* Total Error (95%)

Small gaps 38 110 179 35.3 37.0 050 125 175 25.3 Medium gaps 36 109 271 29.4 34.9 086 106 192 24.1 Large gaps 34 118 308 28.2 30.7 098 074 172 21.8 Small clearfell 33 158 613 36.2 39.2 084 149 233 13.9 Large clearfell 33 123 520 23.2 29.4 060 077 137 20.0 Shelter wood (30%) 39 114 114 36.8 36.8 155 140 295 09.6 Shelter wood (50%) 37 126 146 42.4 43.5 175 148 323 20.8 Seedtree 36 108 300 33.2 38.0 116 160 276 12.3

*RL = residual log



by basal area was 35% E. sieberi, 24% E. globoidea, 24%E. baxteri, 13% E. consideniana and 4% E. botryoides.

Study design

The work reported here is entirely concerned with Phase 1 ofSSP, namely, the establishment and monitoring of the mainexperiment and related research studies in LF on the CabbageTree site.

Coupe-level treatments

Eighteen treatments are being evaluated: 9 harvesting treatments× 2 seedbed preparation treatments. The aim was to replicateeach treatment at least twice in two successive years. The nominaltreatments are presented below. Details on the implementationof these treatments in the forest follow, along with informationon the level of replication actually achieved.

Harvesting treatments

The nine harvesting treatments represent points along twocontinua, one of increasing gap size and the other of decreasingoverwood retention. Unharvested forest represents the startingpoint for both continua, that is, a 0-ha gap and 100% overwoodretention (Fig. 2). The treatments are given below in setscorresponding to the silvicultural systems to which they arerelated:

• Clearfell (10-ha or 4-ha opening)

• Seedtree (retain 5 seed trees ha–1)

• Shelterwood (retain 30% or 50% of coupe basal area)

• Selection (0.03-ha, 0.25-ha or 1.00-ha opening)

• Unharvested forest.

Seedbed preparation treatments

The two seedbed preparation treatments are those judged mostlikely, from research and operational experience in East Gippslandforests (Squire et al. 1984; Fagg 1987; Squire et al. 1991), toprovide soil conditions favourable for seedling establishment and

healthy growth, namely mechanical disturbance and slash-burning.

Seed supply

With the exception of the clearfell treatments, seed for regenera-tion was to come from retained trees, either on the coupe (i.e.seedtree and shelterwood treatments) or surrounding the coupe(i.e. canopy gap treatments). By definition (Squire et al. 1991),clearfell treatments were too large in area to be adequately seededby surrounding trees. These treatments were to be seededartificially with raw seed collected from trees felled duringharvesting of several coupes within the experimental area. Forthe other treatments, seedfall was expected to occur naturallywhere mechanical disturbance was used for seedbed preparation,and to be induced (Cremer 1965) where slash-burning was used.

Field layout (coupe planning)

Constraints on coupe location

The full study design required a minimum of 72 coupes, that is,18 treatments × 2 years × 2 replications. Ideally, from a statisticalperspective, these coupes would be located at random within thegross site area of some 580 ha. At the very least, a blockingtechnique was planned to reduce the potential for treatment effectsto be confounded with the effects of, say, soil and/or vegetationdifferences. In reality, the process of locating coupes was subjectto the following important constraints, namely to:

• comply with the Code of Forest Practices for Timber Production(DCFL 1989a; DNRE 1996). There were significant restrictionson the location and construction of roads, tracks and loglandings, harvesting in the vicinity of streams and for protectionof rare fauna (i.e. the long-footed potoroo, Potorous longipes).

• limit vegetation and soil variation between coupes. Thisresulted in all coupes being located in LF (mostly in sub-communities, 1.2 and 1.3) and, essentially, in the principalsoil types.

• exclude shelterwood coupes from the area north of EmphieldsTrack and south of Falls Creek that had been selectively loggedbefore 1970.

• aggregate some 30% and 50% shelterwood coupes to meetthe design requirements for planned studies of harvesting safetyand productivity.

A map was prepared showing coupe locations and boundariesand treatments allocated to coupes (Fig. 3). About 6 km of roadsand tracks were constructed and another 4 km upgraded duringthe establishment of the experiment.

Statistical implications

As a result of the above constraints, the net area available forlocating the target of 72 coupes was considerably less than 580 ha,and there was no scope for sophisticated statistical refinements.Statistically, the outcome of the coupe location process was, notsurprisingly, somewhat less than ideal. Slash-burning was the onlyseedbed preparation treatment used in combination with the 10-haclearfell treatment. Otherwise, all of the harvesting × seedbedpreparation combinations were replicated in space and most werereplicated in time. However, coupes were not really located at

Medium gap Large gap

Small clearfell

Large clearfell

10% overwood30% overwood

50% overwood

Unharvested forest

Small gap

Increasing gap size

Decreasing overwood retention

Figure 2. Harvesting treatments, depicted as two continua, one for gapsize and the other for overwood retention, in the Silvicultural SystemsProject experiment in lowland forest at Cabbage Tree Creek in EastGippsland, Victoria



Figure 3. Location of treatment areas at the Cabbage Tree site

random, and replication was unbalanced (Table 2). The target ofa minimum of 72 coupes was exceeded, the actual total being 94.

Implementation of treatments

Harvesting

Pre-harvest assessment of seed supply

Great care and rigour were applied to ensure that the seed supplycriteria of the main experiment could be achieved, as follows:

• The minimum quantity of seed required was taken to be 50 000viable seeds ha–1, based on the research undertaken in similarforest in East Gippsland by Fagg (1987). This is well belowthe operational rate in clearfell mixed-species in Victoria(150 000 viable seeds ha–1), a rate that often results in veryhigh seedling stockings in LF.

• The seed was to be distributed uniformly over the coupe.

• The species composition of the seed to be applied to theclearfell treatments was 35% E. sieberi, 24% E. globoidea,24% E. baxteri, 13% E. consideniana and 4% E. botryoides.For all other harvesting treatments, the seed supply was to beby natural seedfall from standing living trees (i.e. trees retainedafter harvesting) and, as far as practicable, the species mixtureof the seed crop retained on the coupe was to match that of thebasal area of the original stand.

Assessment of seed supply was confined to those treatments thatinvolved retaining a carefully selected set of trees on the coupeto provide an above-ground seed source for the eucalypts, asfollows:

Seedtree coupes: a uniform distribution of seed was expected byretaining trees at the local prescribed rate of 5 ha–1 (Lugg et al.1993) at a spacing of about 45 m (Fig. 4). The seedcrop retainedwas about 400 000 viable seeds ha–1 (Bassett and White 1993).

Shelterwood coupes: trees were selected for retention on the basisof spacing (uniformity), species and stem diameter. Only treeswith a diameter at breast height over bark (dbhob) > 40 cm wereselected. Otherwise, the diameter distribution of the selected treeswas the same as that for the original stand. Given that the basalarea of retained trees (i.e. 30% or 50% of that of the originalstand) was much higher than for the seedtree system (i.e. 10%),less importance was attached to the seedcrop size for individualtrees. An additional consideration in the shelterwood treatmentwas that the retained trees would provide shelter that may assistsuccessful germination and seedling establishment by, forexample, reducing temperature extremes at ground level.However, present knowledge is very limited for this and relatedforests, so no special criteria were applied for selecting trees onthis basis.

LC -bST-d

LG -b

MG -dSC -dMG -b

LG -d

MG -d

ST-d

LG -d

LG -b

SG-b

LG -bSW50-d

SW50-bSW50-d

SG -d

M G -d

SC -b

SW 30-b

SW 30-b

SW 30-dST-d

ST-b

MG-b

SG-bMG-b

LC-bSC-d

SG -dM G -b

SG-dSG-b SG-d

SG-bSG-d

MG -d

ST-bST-b

SW50-d

ST-dSC -b

SW30-dSW30-b

SW50-bSW50-d

SW100-bSW100- d

LC -b

SC- b

LG -b

MG -b

LG -dSW100

SW 100-d

MG -b

SG -b

SG -b

MG -d

LG -d

SG -b

SW 30-b

MG-d

LG -d

MG-d

LG -b

SG-b

SG-d

SG-bSG-d

MG-b

LG -d

SW 30-d

SW 30-b

M G -b

SG -d

LG -b

SG-b

LG -d

SG-d

LG-bMG-d

ST-bSG -d

SG -d

1000 0

Silvicultural Systems Project

Cabbage Tree

N

EW

S

SC-d

LC-b

SW30-d

SW30-d

SC-d

SC-bLG-b

LC - 10 ha clearfellSC - 4 ha clearfellLG - 1 ha gapMG - 0.25 ha gapSG - 0.03 ha gapST - seed treeSW30 - 30% shelterwoodSW50 - 50% shelterwoodSW100 - 100% shelterwoodd - disturbedb - burnt

1000 metresEmphieldsTrack

Winter Road

Falls Creek

Cabbage

Tree Creek

A B C D E F G H I J K L M

1

2

3

4

5

6

7

8

9

10

11

Falls Creek

Road No. 1



Generally, selection of trees took place up to 3 mo before harvest-ing. No assessment of seed supply was required for the clearfelltreatments as they were designated for artificial seeding, or forthe selection openings, as it was assumed that the edge trees wouldbe an adequate seed source (i.e. quantity and species composition)(Squire 1987).

Harvesting prescriptions

Timber harvesting operations were guided by local operationalexperience and prescriptions, and were conducted in accord withthe Code of Forest Practices for Timber Production (DCFL1989a). Detailed prescriptions for silvicultural systems currentlyused in the LF and related forest types are defined in OperationalPrescriptions (DNRE 2001).

Essentially, the harvesting prescriptions were very similar for alltreatments, involving the felling of all trees not marked forretention. Inevitably, some marked trees were felled orunacceptably damaged during the harvesting operation. In suchcases, the faller usually contacted the SSP Harvesting Supervisorwho arranged for selection of a replacement tree (same species,seedcrop, etc.) from others nearby.

Harvesting implementation

Ideally, from a design perspective, harvesting operations wouldhave been standardised, with one logging contractor using thesame equipment and basic techniques for all treatments in spaceand time. This was impracticable, given the magnitude andcomplexity of the harvesting task. Generally, trees were felledmanually by chainsaw, and the logs snigged by bulldozers(variously, either a Komatsu D60-E6, or a Caterpillar D6H orD65H) to a landing, where they were debarked, graded and cutto length, and loaded onto trucks by a crab-grab excavator. In

Figure 4. Regeneration 3 y after slash-burning in a Seedtree coupe atthe Cabbage Tree site

Table 2. Replication of harvesting and site preparation treatments and seasons in the Silvicultural Systems Project experiment at Cabbage Tree Creek in East Gippsland, Victoria

Number of coupes

Burnt Disturbed System Harvest treatment Seed source Nominal area (ha)

and coupe size

1989 1990

1989 1990

Clearfell Large clearfell Air seeding 10.00** 02 02 — — Small clearfell Air seeding 04.00**

200 m × 200 m 02 02 02 02

Group selection Large gap Natural 01.00** 100 m × 100 m

03 04 03 04

Medium gap Natural 00.25** 50 m × 50 m

03 05 03 05

Small gap Natural 00.03** 20 m dia.

03 08 03 08

Seedtree 10% retained overwood* Natural 05.00** 02 02 02 02

Shelter wood 30% retained overwood* Natural 02.00** 02 03 02 03 50% retained overwood* Natural 02.00** — 02 02 02

Unharvested forest Unharvested forest Natural 00.25** — 02 02 02

Total 17 30 19 28

*See Table 4 for the fractions actually retained **4.00 ha in 1989/90



both seasons, however, the harvesting contractors determined,during harvesting, that chainsaw felling in the 50% overwoodretention treatments was unacceptably dangerous to the faller.Although harvesting of these treatments continued, most treesremaining to be felled were pushed over with a bulldozer.

In coupes that were to be mechanically disturbed, the crowns ofharvested trees were left where they fell. In coupes that were tobe burned, crowns falling outside the coupe boundaries werepulled back inside as harvesting progressed. In small gaps whereseedbed preparation by burning was intended, particular effortwas made to heap slash (i.e. crowns and unmerchantable parts ofthe stems) in the centre of the gap so that burning would producean ashbed.

Timing of harvesting

Harvesting commenced in early summer of each year to limitdisruptions due to wet weather, and was completed by late summerin coupes to be burned, to enable curing of slash for autumnburning. Harvesting continued through autumn on coupes to bemechanically disturbed. Thus, the 1989 coupes were harvestedbetween December 1988 and May 1989, and the 1990 coupeswere harvested between January and July 1990.

Harvesting outcomes

Timber yields

Average timber yields for each harvesting treatment are given inTable 3 (Stucken and Hajek 1993). Cumming and Black (1993)compared actual with predicted timber yields using coupes froma restricted set of treatments, namely: 36 coupes made up of eightwith 0.25-ha gaps, 13 with 1.00-ha gaps, eight with 4-ha clearfellsand four with 10-ha clearfells. Generally, actual total merchantablevolumes were greater than predicted, and it was considered thatthis was almost certainly due to the greater-than-normalsupervision of the operations resulting in greater-than-normalutilisation. It appeared that residual log volumes had beenunderestimated; this could be attributed, at least in part, to thedifficulty of applying standards for residual log harvesting, and

to an unusually high incidence of internal defect in logs fromsome coupes resulting in the down-grading of some ‘sawlogs’ toresidual log.

Overwood retention

The amount of overwood retained on a coupe, measured as basalarea per hectare, can be expressed in two ways: first, as thepercentage of pre-harvest basal area and, secondly, as an absolutevalue (Table 4). Both have biological importance as measures ofthe potential for overwood competition to limit seedlingestablishment and growth. The percentage approach was preferredfor SSP. Generally, there was a bias towards leaving too few trees:that is, the actual percentages retained were consistently belowthe targets: for the 10% retention target, the actual mean was7.4% (range 3.7–10.4%), and the corresponding values for the30% and 50% targets were 22% (19–24%) and 35% (19–46%),respectively.

Forest safety study

Bloch and Murphy (1994) assessed the safety of operationalmethods associated with harvesting under the alternativesilvicultural systems. Manual felling, and particularly the treefeller’s exposure to falling trees and branches, had been identifiedas the primary safety concern. Due to the limited study periodand the small number of injuries occurring during the harvestingof experimental treatments, a direct assessment of felling riskwas not feasible. Thus risk was evaluated using the occurrenceof hazards, that is, potentially dangerous events or objects arisingfrom the harvesting operation and which could lead to injury.

Seedbed preparation

Prescriptions

There were two main options for preparing receptive seedbed:broadcast slash-burning and mechanical disturbance. Mechanicaldisturbance involves using a bulldozer to disturb the surfacevegetation and soil, and relocate slash (mainly) into small (about5 m × 5 m), well-distributed heaps. The heaps were to remain

Table 3. Average wood yields by grade for harvesting treatments in the Silvicultural Systems Project experiment at Cabbage Tree Creek in East Gippsland, Victoria (Stucken and Hajek 1993)

Wood grade*

Harvesting treatment C+ sawlog (m3 net ha–1)

D sawlog (m3 gross ha–1)

Residual roundwood (t ha–1)

Large clearfell 39 17 199 Small clearfell 40 18 200 Large gap 34 07 184 Medium gap 41 14 224 Small gap 33 13 233 10% overwood retention 38 15 160 30% overwood retention 27 15 147 50% overwood retention 20 03 095

*Wood grade was based on the DCFL hardwood sawlog grading system: C+ sawlog was the total merchantable volume of A, B and C grade sawlogs net of defect; D was the gross merchantable volume of D grade sawlogs; and residual roundwood was the mass of stemwood with a minimum small-end diameter underbark of 25 cm and which did not meet sawlog-grade standards, but met the then-current residual log standards.



unburnt, to avoid confounding the effects of mechanicaldisturbance and fire. To avoid soil damage the followingprecautions were taken:

• avoiding operation in wet weather

• pushing across slope

• avoiding sub-soil disturbance

• limiting pushing of slash to a distance of 20 m

• avoiding damage to retained trees, by pushing and heapingthe slash away from retained trees.

Slash-burning involved using fire in autumn to consume loggingdebris (termed slash) and prepare an ashbed. Slash-burning wasvaried with harvesting treatment. A high-intensity burn wasprescribed for the clearfell, seedtree and the group selectiontreatments, to maximise seedbed receptivity (i.e. ashbed). In thecase of the seedtree treatments, high-intensity slash-burning wasalso required to maximise induction of natural seedfall. In existingLF, seedtrees usually have highly defective stems and cannot beharvested economically in a follow-up operation. Hence, stem

degrade due to fire damage was of no consequence for the seedtreetreatment. However, a low-intensity burn was prescribed for theshelterwood treatments to minimise fire damage, as it is usualfor the seedtrees, or, shelterwood, to be retained for a considerabletime, perhaps as much as 20 y, after seedfall, and then be harvestedin a commercial operation.

The results of seedbed preparation treatments were compared tothe minimum standards of quantity and distribution specified inoperational prescriptions of the time, that is, 75% of 4-milacreplots should contain at least 80% receptive seedbed (uncompactedbare soil or uncompacted ashbed) (DCFL 1989b).

Implementation

Mechanical disturbance

Coupes were mechanically disturbed during the period 11 April –11 May in the 1989 replication and during the period 11 May –24 July in the 1990 replication. Mechanical disturbance was

Table 4. Comparison of the original and retained basal areas for the seed tree (ST) and shelterwood (SW) harvesting and regeneration treatments in the Silvicultural Systems Project experiment at Cabbage Tree Creek in East Gippsland, Victoria

Basal area Treatment and coupe no. and location coordinates*

Harvest year Coupe area

(ha) Original (m2 ha–1)

Retained (m2 ha–1)

Fraction retained (%)

ST 10% retained overwood — burnt 510/19 (F5) 1989 4.65 41.2 03.5 08.5 510/27 (C3) 1989 4.35 35.0 02.8 08.0 509/19 (J6) 1990 5.12 34.7 02.8 08.1 510/51 (D3) 1990 5.18 37.8 03.3 08.8

ST 10% retained overwood — disturbed 510/05 (A6) 1989 6.18 27.3 02.8 10.4 510/13 (E6) 1989 5.48 36.5 01.9 05.2 510/48 (B4) 1990 5.60 46.5 01.7 03.7 511/01 (E11) 1990 7.49 33.7 02.1 06.2

SW 30% retained overwood — burnt 509/01 (I5) 1989 3.18 34.7 06.7 19.3 510/24 (C5) 1989 3.16 37.6 07.0 18.6 509/08 (J2) 1990 4.25 39.4 08.8 22.3 510/35** (G7) 1990 510/36** (H7) 1990

9.69

37.7 09.1 24.1

SW 30% retained overwood — disturbed 509/02 (J5) 1989 2.46 32.7 06.6 20.2 510/25 (C5) 1989 1.97 44.6 10.0 22.4 509/06** (J4) 1990 509/07** (J3) 1990

7.86

36.5 08.4 23.0

510/37 (H6) 1990 4.08 37.4 08.9 23.8

SW 50% retained overwood — burnt 510/33 (D7) 1990 2.84 49.8 09.3 18.7 510/42 (C5) 1990 2.22 41.0 16.0 39.0

SW 50% retained overwood — disturbed 510/14 (E7) 1989 2.66 34.0 13.4 39.4 510/26 (C6) 1989 2.57 41.5 12.4 29.9 510/32 (C7) 1990 2.51 35.1 16.2 46.2 510/50 (C3) 1990 2.86 37.8 13.6 36.0

*The location coordinates refer to Figure 3. **Coupe boundaries were hard to define, so the areas were combined and averages of basal area are given where necessary.



achieved using bulldozers fitted with root-rakes: a Komatsu D85Ein 1989, and a Caterpillar D6D and D7G in 1990. Although thedisturbance was carried out to prescriptions, the stems of someretained trees were damaged through abrasion caused by thebulldozers or the heavy slash being pushed by them. The smallestgap treatment produced such a small opening in the forest (i.e.0.03 ha) that it was necessary to push the slash and understoreyinto the surrounding forest.

Slash burning

Prior to burning, fire control lines were established around theperimeter of the coupe, using bulldozers. All coupes were lit byhand using liquid fuel drip-torches. Coupes were burnt duringthe periods 12–18 April in 1989 and 9 March – 27 April in 1990.

For the clearfell and seedtree treatments, the objective ofachieving high-intensity burns was not met in 1989, because ofunsuitable climatic conditions. ‘Patching-out’ was done toincrease the amount and distribution of ashbed, in the daysfollowing the initial burn. In 1990, however, most burns were ofhigh to very high intensity (Fig. 5); resident heat was still veryapparent the day following the burns and patching-out was notrequired; crown scorch was common in the seedtree treatmentsand some trees died as a result.

For the shelterwood treatments, burns were carried out on coolerdays to produce light to moderate burns, mainly to avoid firedamage to retained trees. This objective was easily achieved in1989. Patching-out was common in both years. Even in 1990crown scorch was uncommon, and in neither year did it causeany tree deaths.

For the gap treatments, in both years, the slash-heaps in the smalland medium gaps (i.e. 0.03 and 0.25-ha openings) were difficultto ignite and, once alight, had to be hand-stoked to produce anashbed of any sort.

Seedbed study

Stucken and Hajek (1993) carried out a seedbed study to comparethe characteristics of seedbeds developed under alternativeharvesting and seedbed preparation treatments. The system ofseedbed classification of King and Cook (1992) (Table 5) wasused, with one significant change: slash cover was recognised asa disturbance process in its own right, whereas disturbance tothe understorey vegetation was regarded as being implicitly linkedto soil disturbance. In general, in terms of existing knowledge ofseedbed requirements of eucalypts (Squire et al. 1991; Campbell1997a), both site preparation methods exceeded the minimumreceptivity standard (DCFL 1989b), as defined previously.

Overall, results show that mechanical disturbance produced morereceptive seedbed than did slash-burning. Within the mechanically-disturbed treatment, only the small clearfell (4 ha) harvestingtreatment was sub-standard, with 73% receptivity. Within the

(a)

(b)

(c)

Figure 5. Time sequence in a 10-ha clearfell at the Cabbage Tree site:(a) January 1990 before harvesting; (b) July 1990 after harvesting andslash-burning; (c) February 1993 after regeneration establishment



slash-burning treatment, only two harvesting treatments were sub-standard, namely, the medium gap (0.25 ha) with 68% receptivity,and the 30% shelterwood with 74% receptivity. Although 19 ofthe 45 individual burnt coupes were sub-standard, most of theseexceeded 65% receptivity. The main reason for the sub-standardresults was that many burns, especially in 1989, were conductedunder unfavourable climatic conditions, partly because alloperations had to meet a very tight timetable.

Soils and nutrition study

A collaborative research program between the CSIRO Divisionof Forestry and the Victorian Department of Conservation andNatural Resources (DCNR), a predecessor of the present DSE,commenced early in 1988 centred on SSP at the Cabbage Treesite in East Gippsland. The work focused on nutrient cycling andtree nutrition (CSIRO 1991). CSIRO (1991) demonstrated that thesoils supporting Low Elevation Mixed Species Forests (LEMS)and related forests (i.e. LF and coastal mixed-species forests) inEast Gippsland are of low fertility. Whilst both N and Pavailability limit forest growth, P is extremely deficient. Thus forestharvesting and site preparation practices, which have the potentialto change soil nutrient-supplying capacity, may directly affectforest productivity. Subsequently, the research program expandedto include studies on the effects of soil P availability on growth,root properties, P status of young eucalypts, and the response toP inputs in fertiliser, to determine the potential to manage nutritionto benefit forest production (CSIRO 1993).

Seed supply

Prescriptions

As so little was known of the requirements for successful eucalyptregeneration under different conditions of overwood competition,especially those imposed by selection and shelterwood systems,it was decided (Squire 1987) to set a minimum seeding standardfor all treatments, based on the research of Fagg (1987) for LF-related forests subject to clearfelling, and the analysis of Squire

et al. (1984). The minimum standard was set at 50 000 viableseeds ha–1 with a species composition that matched the averageproportions by basal area of the five main species in originalforest, namely: 35% E. sieberi, 24% E. globoidea, 24% E. baxteri,13% E. consideniana and 4% E. botryoides. It was accepted thatthe natural seed supply from ‘edge trees’ surrounding a coupe,especially for small coupes (i.e. gap treatments — Fig. 6), couldvary greatly from the average species composition of the CabbageTree site.

For clearfell coupes in LF, some 5% of seed was expected toresult in healthy, well-formed seedlings about 2 y after seeding.For a seeding rate of 50 000 viable seeds ha–1, this equates toabout 2500 seedlings ha–1 which, according to the analysis ofEdgar and Opie (1976), should be adequate where sawlog andpulpwood production are important objectives of management.

Implementation

Artificial seed supply

An artificial seed supply was relied upon for the clearfelltreatments (i.e. 4 ha and 10 ha). A separate seed collection wasmade in each year (i.e. 1989 and 1990) from a selection of coupes.Seed from the five main eucalypt species (see above) wascollected from felled trees, and bulked by species (i.e. 5 bulkedlots). The bulked lots were mixed in the prescribed way (seeabove), and applied using a helicopter fitted with an Albertaseeder, at 50 000 viable seed ha–1 (based on germination tests) tothe 1989 coupes on 9 May and to the 1990 coupes on 30 May. Toachieve an even distribution of seed, each coupe was seeded twiceat half the chosen final rate, using flight-lines at right angles.

It can be deduced from the information on the likely seedfallfrom edge trees that the edges of the clearfell coupes would havereceived a considerable amount of natural seed fall, with up to35% of the smaller coupe receiving an adequate quantity of seedfrom that source alone.

Table 5. Seedbed classification system used in the Silvicultural Systems Project experiment at Cabbage Tree Creek in East Gippsland, Victoria (Stucken and Hajek 1993)

Attribute and level Definition

Soil disturbance Undisturbed Soil, litter and understorey vegetation intact Litter disturbance Litter and understorey vegetation disturbed, but topsoil intact Topsoil disturbance Topsoil, litter and understorey vegetation disturbed Subsoil disturbance Subsoil, litter and understorey vegetation disturbed; different colour and/or texture of subsoil usually visible

Slash cover Nil No slash Light slash Slash less than 7 cm in diameter prevailing Heavy slash Slash more than 7 cm in diameter prevailing

Fire Unburnt Slash, understorey vegetation, litter and subsoil unburnt Low intensity Light slash, understorey vegetation or litter charred or partially reduced to ash or charcoal Moderate intensity Heavy slash charred only; light slash, understorey vegetation and litter reduced to ash or charcoal High intensity All fuels reduced to ash or charcoal; soil may be oxidised to an orange colour



Natural seed supply

Natural seed supply was relied upon for all treatments other thanclearfell. It seems that in all cases seed supply greatly exceededthe prescribed minimum quantity. However, estimates of the seedcrop in the retained trees and the unharvested forest indicate thatin some cases the species composition objective was not achieved(see Seed supply study, below).

Seed supply study

Bassett and Geary (unpublished data) conducted a detailed studyof the implementation and monitoring of seed supply aspects ofthe seedtree (10% retained overwood), shelterwood (30% and50% retained overwood) and unharvested forest (100% retainedoverwood retention) with mechanical disturbance or slash-burning. A field technique developed for assessing seedcrops inmountain ash (E. regnans) regrowth in Central Victoria (Harrisonet al. 1990) was adapted for use in LF (Bassett and White 1993).The technique estimated the total seed crop on an individual treeand, by aggregation, the seed supply on a full set of trees.

Following the implementation of seedbed treatments, seed traps,positioned according to a stratified random sampling procedure,were used in a study of the timing, quantity and spatial distributionof seedfall in the seedtree and shelterwood treatments, and alsoin the unharvested forest (Bassett 1995). In slash-burnt treatments,seedfall was measured intensively for a period of 6 mo after sitepreparation, by which time inducted seedfall had finished, andabout 35–50% of the estimated seed in the canopy had fallen. Inmechanically-disturbed treatments, seedfall was also measuredintensively over the 6 mo following site preparation, by whichtime about 10–25% of the seed in the canopy had fallen. Seedfallcontinued to be measured, although less intensively, for a further18 mo in mechanically-disturbed treatments, because seedfallwas not declining and there was continued germination over this

period (Faunt et al. 2006). The implicationsof intense seedfall soon after slash-burningwere that seedcrop stores were soonexhausted in slash-burnt treatments, andcumulative seedfall was ‘catching up’ onmechanically-disturbed treatments over thenext 18 mo.

Seeds could not reliably be separated byspecies, so species composition outcomeswere determined from post-germinationdata, including those from long-term studiesof species dynamics (i.e. survival andgrowth). Seed supply was not studied forthe group selection systems (i.e. 1.00, 0.25and 0.03-ha gaps). However, the likelihoodof success, at least in terms of the quantityof seed supply, can be judged from the greatabundance of seed in the unharvested forest(Bassett 1995), and from the distance ofeffective seedfall from an edge of trees,which is likely to be 0.5 to 1.0 times treeheight (Cremer 1977).

Cost study

Sharp (1993) evaluated the cost-effectiveness of differentharvesting and seedbed preparation treatments (i.e. regenerationtreatments) used in the SSP experiment in LF at the CabbageTree site in East Gippsland. Evaluation of cost-effectiveness waslimited to the timber production objective, because environmentaloutputs could not be quantified. Evaluation was furthercomplicated by an element of risk associated with uncertainty inthe management system. For example, there was a risk that slash-burn fires would escape and require suppression, and evaluationinvolved estimating both the probability of fire escape and theresultant costs.

In the analysis of cost-effectiveness, inputs were confined to on-coupe costs adjusted for risk, and outputs to future timber yields.All costs ($ ha–1) were discounted, at 4% real discount rate(Government of Victoria 1986), back to the beginning of the cycle.Cost-efficiency ($ m–3) was calculated by dividing the discountedoperational cost by the discounted timber yield.

Regeneration monitoring

Prescription

The success of the combined harvesting, seedbed preparationand seed supply operations was determined by the eucalyptstocking survey result, that is, the proportion of 16 m2 samplingplots containing an ‘acceptable’ eucalypt seedling at 1–3 y afterregeneration treatment. The regeneration assessment procedurethat was operationally applied in Victoria at the time (Squire etal. 1991) compared the percentage of stocked 16 m2 plots with acoupe-level standard of 73% at age 1 y and 65% at age 2–4 y.Faunt et al. (2006) discuss the problems in applying a commonacceptability criterion across the range of harvesting treatments,and the importance of using other criteria of success in additionto the regeneration survey result.

Figure 6. Aerial view of 1-ha gaps and a 4-ha clearfell in May 1989 after harvesting of thefirst year’s replication at the Cabbage Tree site. The 1-ha gap is the maximum size that islikely to be seeded adequately (i.e. in quantity and distribution) by edge trees.



Implementation

Regeneration surveys used the standard operational samplingapproach in the larger treatment areas, sampling plots beinglocated at 20-m intervals along transects spaced 80 m apart. Thesampling procedure was modified to suit the small areas in theunharvested and selection openings up to 1.00 ha in size (Fauntet al. 2006). Surveys were carried out at age 1 y in the 1989 and1990 coupes. In the 1989 replication a large number of coupesdid not meet the standard and thus surveys were conducted againat age 3 y in the 1989 replication. At the second survey, theseedling density was also measured using triangular tessellation(Ward 1991) in addition to the stocked-plot method. In the 1990replication, most coupes met the standard at the survey at age 1 y(Faunt et al. 2006).

Eucalypt germination and survival study

Studies of eucalypt germination, survival and growth were animportant starting point for assessing the potential for clearfelland alternative silvicultural systems to meet two key managementobjectives: (i) to ensure site capacity is fully utilised andsustainable wood production is maximised, and (ii) to ensure thespecies composition of the new forest matches that of the original.

The eucalypt regeneration study provided data on seedlingdensity, height growth and species composition at an early stageof stand development (Lutze 1998a; Faunt et al. 2006), and thiscan be used to predict, albeit very approximately, future standdevelopment and wood production (Hamilton 1989). Thisinformation can also enhance understanding of the way the keyregeneration processes (germination, survival and early growth)are influenced by seed supply (timing, quantity and distribution),seedbed (type, quantity and distribution) and the environmentalconditions of light, temperature and moisture. In particular, thestudy will assist in identifying, for each overwood treatment, theseedbed preparation and the amount of seed of relevant speciesrequired to secure adequate regeneration to meet the objectivesof management.

Understorey regeneration study

The understorey regeneration study has provided data on coverand height of plant life forms (Faunt et al. 2006) at 1.5 and 2.5 yafter regeneration operations. This information has been used todetermine the rate of recolonisation of burnt and disturbed soilby non-eucalypt vegetation. It indicates how the understorey hasinfluenced regeneration timing and success, through the reductionof seedbed receptivity and competition with establishing eucalyptseedlings.

Flora study

Conservation of floristic and other biodiversity values is animportant objective in managing native forests for sustainablewood production. The flora study (Ough and Minchin 2000)aimed to determine the effects of harvesting and seedbedpreparation treatments on the floristics of the regenerating forestand determine whether the floristics of the regenerating forestare different from those of nearby unharvested forest. A selectionof 64 of the plots surveyed prior to harvesting (see Vegetation;

Stuwe and Mueck 1990) was reassessed using the same methods2–4 y after treatment. Plots were selected to provide replicationacross the sub-community × treatment combinations. However,many treatments were not represented or had insufficientreplication, because the original flora sampling and treatmentdesigns were not coordinated. Consequently, an assessment usingan expanded sampling design was implemented 10 y after sitepreparation (Turner et al. 2004). Although all plots do not havepre-harvesting data, the new sampling design should providebetter information about the longer-term recovery of flora afterthe various silvicultural treatments.

Acknowledgements

The Silvicultural Systems Project (SSP) arose from the VictorianTimber Industry Strategy, led by Dr Bob Smith and released in1986. It resulted in an exceptional co-operative effort to provideVictorians with the sound scientific basis required to achieve anobjective balance between sustained timber production andecosystem conservation in the management of the State’s nativeforests. At its pinnacle, SSP involved inputs from well over 100scientists and other people from the then Department ofConservation and Environment, industry, community groups,trade unions and external research institutions such as CSIRO.All of these people have directly or indirectly contributed toachievements described in this report.

SSP Cabbage Tree is, without question, a tribute to theoutstanding leadership and professionalism of the late researchforester, Peter Geary. His vision, energy, tremendous all-roundcompetence, commitment and total reliability were an inspirationto the many others who worked with him, including scientistsfrom external research institutions such as CSIRO.

Dr David Flinn provided excellent leadership and managementthroughout the establishment of the experiment. Owen Bassett,Peter Fagg, Karen Faunt and Simon Murphy gave guidance onthe content and provided valuable feedback on the draft report.Dr Maureen Murray and Tanya Burton produced the tables and,with specialist assistance from Greg McCarthy, generated thefigures.

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