Our Valuable Native Grasslands, Better Pastures Naturally
Proceedings of the Second National Conference of the Native Grasses Association

The Dookie Bushland Reserve

Adam Whitchurch and Steve Hamilton

Institute of Land and Food Resources, Dookie College, University of Melbourne, Victoria, 3647, Australia.

Abstract

The Dookie Bushland Reserve (DBR) is an area of 270 hectares of Grey and White Box grassy woodland located on the Dookie College campus of the Institute of Land and Food Resources (ILFR), University of Melbourne. It has had a varied land use history, with no agricultural impact until the mid-1960's when some areas were utilised for grazing; however, a central area remained with little or no impact until 1992. Adjacent areas of the College had been undergoing clearing since 1890.

Some areas of the DBR were utilised for timber harvesting, and small areas for gravel extraction. The peripheral areas were re-combined with the intact central area in 1992 to form the Dookie Bushland Reserve (DBR). Management Plans have been written in 1993 and 1999 (Hamilton 1993 & 1999), and these have formed the basis of management until the present day, as well as providing an up-dated inventory of the flora and fauna.

The original Management Plan set some generalised management directions, which has led to significant progress being made since the earlier days of declaration in terms of conservation objectives. Some of the key events have been the completion and maintenance of the feral animal fence. The employment of part-time Rangers with on-going and significant pest animal and plant management. A dramatic improvement in the structure and habitat quality due largely to natural regeneration and grazing pressure reduction, and the on-going incorporation of the DBR into the Natural Resource Management (NRM) academic programs of the College.

The DBR today is a large high quality remnant of some of the original vegetation of the northern plains of Victoria, particularly the threatened Ecological Vegetation Class of Low Rises Grassy Woodland and Box-Ironbark Woodland. It is highly valued for the intactness of these community associations, and the diversity and uniqueness of its flora and fauna, including many threatened species, and as a consequence, is listed as an indicative site on the Register of the National Estate.

Introduction

In the Goulburn-Broken catchment, an area of 2.4 Mha, Ecological Vegetation Classes (EVC's) known as Box-Ironbark Forests and Woodlands and Plains Grassy Woodlands once dominated the northern slopes of the Great Dividing Range and the Riverine Plains, with 290,000 ha and 850,000 ha area respectively (Goulburn Broken Catchment Management Authority (GBCMA) 1999). Early settlers cleared and extensively grazed these areas, and ultimately, the extent of these woodlands and forests has become greatly reduced, and remnants have become highly fragmented and isolated over time. Only some 20 % of Box-Ironbark Grassy Woodlands and 2 % of Plains Grassy Woodlands now remain (GBCMA 1999).

Many of the remaining areas of grassy woodlands are small, and have been grossly disturbed by direct or indirect influences. Localised and regional depletion or extinction of significant numbers of species of flora and fauna has occurred because of this loss of habitat and modification. Because policy makers and the general public have viewed these EVC's as neither very scenic nor interesting, those remaining areas of significance have generally not been reserved or managed as conservation zones. Indeed, these EVC's are very poorly represented in the reserve system, with only 0.8 % of the original Box-Ironbark Forests and Woodlands and 0.15 % of Plains Grassy Woodlands reserved (GBCMA 1999). It is hoped that the Special Investigation into the Box-Ironbark Forests and Woodlands by the Environment Conservation Council (ECC) currently being finalised will significantly improve the reservation status of the former EVC. Options such as Protected Area Networks, which incorporate the biodiversity on public and private land, need to be pursued to ensure adequate conservation of these EVC's. Indeed, it has been shown that many of the best remnants of Box-Ironbark, in particular, are on private land (Hamilton et al. 1997; Dettmann et al. 2000).

The DBR is an area of national significance for both its community associations (150 ha of Low Rises Grassy Woodland and 120 ha of White Box Grassy Woodland), the threatened species that it contains, and its size. It is considered to be the single largest and most diverse area of White Box Grassy Woodland remaining in Victoria (Peake pers. comm. 1999). It is unique in that it is a large intact remnant (270 ha) contained within a working agricultural property (the Dookie College property of 2,500 ha). It is because the historical and current emphasis of farm management of the College was, and still largely is, predominantly for educational purposes that we still have the Reserve as an intact entity today. We are indeed very fortunate to have the opportunity to maintain and enhance such a significant site.

This paper provides a background to features of the Bushland Reserve and its history.

Background

The DBR is an area of approximately 270 hectares of Grey and White Box (Eucalyptus microcarpa and E. albens, respectively) grassy woodland located centrally on the Dookie College campus of the ILFR, a faculty of the University of Melbourne. It is composed of several paddocks of the College property which had a varied land use history from the mid 1960's until 1992, when the area was largely excluded from agricultural activity, and the area defined as the DBR. Most of these paddocks had been used for grazing and/or limited cropping, while the paddock called the Timber Reserve had been generally excluded from any agricultural activity.

Land Status

The entire Campus remains classified as reserved Crown Land for the purposes of agricultural education (Land Conservation Council (LCC) 1983), and is the responsibility of the now Department of Natural Resources and Environment (DNRE).

Climate

The climate of the DBR (based on the permanent weather station at Dookie College) is typically Mediterranean, with an average annual rainfall of 556 mm and 99 rain days, mostly in the winter months. Approximately 330 mm of this rainfall falls in the period May to October, and there are on average 22 frosts annually, usually between April and September. Evaporation exceeds rainfall from September to April, and direct sunlight hours varies from 12 in the summer, to less than 7 in the winter. The maximum mean monthly temperature is 21.6 °C in February, and the minimum mean monthly temperature is 3.7 °C in July. Summer temperatures can exceed 41°C (Victorian College of Agriculture and Horticulture (VCAH) Dookie 1992).

Land Information

The elevation of the DBR ranges from 165 to 237 metres above sea level, and contains the full range of aspects. Flat, ridge areas occur at elevations greater than 200 metres above sea level, and some areas of gentle slopes to flat topography occur at elevations of 165 to 180 metres.

Recent soil survey has discovered only two distinct soil types in the DBR, and that the types categorised as Gowangardie Loam (a tenosol) and Caniambo Loam (a brown chromosol) by Downes (Downes 1949) and known as these in common usage since, are classified by Isbell (1993) and Northcote (1983) as the same soil type.

Land management history

There is relatively little known regarding the Aboriginal history of the area (LCC, 1983). The main tribe in the Dookie region appear to have been the Noorilim, who ranged from the Campaspe River to the Dookie Hills. With no permanent creek or river, it is unlikely that the DBR was a site of settlement, and was most likely an area for hunting and the gathering of items such as stones or rocks (Envall et al. 1988).

Major Sir Thomas Mitchell passed through the district (more specifically, Benalla) on his return to Sydney from Portland in 1836. His glowing endorsement of the region opened up the way for agricultural development (Aldridge 1986).

In 1875, following a series of leaseholders, the then Secretary for Agriculture requested that the undeveloped area now called Dookie College be reserved for the purposes of establishing an Experimental farm (Aldridge 1986).

Much of the property was cleared by 1930, however, the DBR has had a relatively recent land use history, with no agricultural impact until the mid-1960's. Then peripheral areas were incorporated into larger paddocks and utilised for domestic stock grazing (mostly sheep) and limited cropping, with significant areas fertilised aerially with superphosphate.

Historically, the DBR area does not appear to have been greatly utilised as an educational resource or an area of conservation value. Agriculturally, it was seen as mostly marginal and unprofitable, which was infrequent utilised as a source of timber and gravel, and was of use in extreme circumstances for grazing. It is the agriculturally "unproductive" view of the DBR area by management that more than likely saved it from clearing (Hamilton 1999).

A central area with little or no agricultural impact, referred to as the Timber Reserve, remained until 1992. Some areas were utilised for timber harvesting (during the 1950's and 1960's), and small areas for gravel extraction (rock for road surfacing, mostly during the 1960's and 1970's). Peripheral areas were re-combined with the minimally disturbed central area in 1992 to form the DBR. There is no record of wild fire within the DBR since European settlement (Hamilton 1999).

The majority of the DBR has not been deliberately grazed since 1990, however, the area has suffered from the grazing impacts of a large indigenous Eastern Grey Kangaroo population (estimated > 700 animals) during the period 1988 to 1992. This population has since been reduced by permit culling to the estimated carrying capacity of 100 animals and maintained at that level.

Due to the significant grazing impact, in 1991/92, the DBR area was no more than an established overstorey canopy with no regeneration, shrubs taller than 3 metres in height only, and some ground layer shrubs that were either prickly (e.g. Spreading Wattle, Acacia genistifolia, and Gorse Bitter-pea, Daviesia ulicifolia) or otherwise unpalatable to herbivores (e.g. Slender Rice-flower, Pimelia linifolia spp. linifolia). In essence, there was little plant material at ground level to 1.8 metres in height (kangaroo grazing height)(Hamilton 1995).

The declaration of the DBR in 1992/93 coincided with two summers of well-above average rainfall in 1992/93 and 1993/94, which, when combined with the removal of stock grazing and reduction in kangaroo levels to carrying capacity, resulted in a dramatic regeneration of vegetation. This event rapidly re-established a grass and herb layer at ground level, a shrub layer, and regenerating Eucalypts. This provided an excellent basis for the re-establishment of a grassy woodland structure that continues to this day (Hamilton 1995).

While regeneration of the DBR has been profound, the 27 years of agricultural impact (i.e. stock grazing) has had an ecological impact. Some recently completed research (Hamilton 2001) has evaluated the changes in plant species cover and abundance. It has concluded that agricultural impact over a 27 year period (1965-1992) had contributed to significant declines in the number and cover of indigenous species, and significant increase in the number and cover of introduced species.

The loss of shrub species, juvenile eucalypts, and the dominance of tussock-forming indigenous grasses with increased agricultural impact (i.e. increased grazing utilisation) was observed. Individual species responded differently to increased agricultural impacts. Some species, particularly non-tussock forming indigenous grasses and introduced annuals, were promoted in establishment and cover by increased grazing impact, while others, most notably Orchidaceae and Liliaceae, were intolerant of any impact. Certain groups of indigenous species, particularly the Asteraceae (daisies) and tussock- forming indigenous grasses, were reduced significantly in cover by increasing grazing impact.

The original management plan, produced in late 1993 (Hamilton 1993), provided an initial framework for the management of the area, as well as greatly assisting the public and industry profile of the site. This has certainly assisted in funding for the completion of works. The original Management Plan was revised in 1999 (Hamilton 1999).

The feral animal "deterrent" fence that was constructed over the period of 1993-1997, has finally afforded the opportunity to permanently exclude stock, and to some level, deter feral animals. Internal fences have been removed where no longer necessary during the period 1994-1996.

There has been increasing and more systematic management of the DBR on a number of major issues since 1993, such as pest animal management and weed management, especially Horehound, Thistles, St. John's Wort, Paterson's Curse and European Olive. While the effort has been largely undertaken under the auspices of various Higher Education and TAFE subjects, the effort has been yearly and consistent, and more-or-less co-ordinated.

Weed management efforts in particular, are clearly being moderately successful in tackling the major weed issues, with the almost complete eradication of the major thistle weeds, and significant control of Horehound, Paterson's Curse and European Olive (all reduced to less than 50 % of their 1992 distribution).

In 1995, an application for the listing of the DBR on the Register of the National Estate was submitted, and this application has seen the DBR currently listed as an indicative site on the Register (Hamilton unpublished 1999).

Since 1995, the College has employed part-time Rangers, in all cases students within one of the NRM courses, on an annual contract basis. The major duties of these Rangers have been to provide tours and interpretation to visiting College groups, however, they have other routine duties, such as checking the feral animal fence, clearing tracks and acting as a link between staff and on-ground activities.

Vegetation structure and composition

Based on a mixture of anecdotal evidence, observation of the less disturbed areas of the DBR, and the few other minimally disturbed district and regional grassy woodlands (Hamilton unpublished 1999), a typical grassy woodland in the district is generally dominated by a box eucalypt canopy with projective foliage cover (pfc) between 25-40 %, and ranging between 7-15 metres in height, the maximum height (and pfc) being strongly related to exposure, elevation and the depth of A horizon. Such ecosystems would likely be categorised as low or medium open-woodlands or woodlands (Groves 1999).

The White Box woodland occupies areas of shallow, stony uniform textured brown soils. White Box is the dominant overstorey species. Other overstorey species, such as Yellow Box (E. melliodora), Lightwood (Acacia implexa), Cherry Ballart (Exocarpus sp.), Drooping She-oak (Allocasaurina verticillata) appear to have been widespread in this soil type, although their distribution throughout the DBR is now clumped, for reasons of probable grazing and selective clearing pressures (Hamilton 1999).

The understorey is generally composed of two sparsely distributed shrub layers of Acacia spp. (e.g. Golden Wattle A. pycnantha, or Spreading Wattle A. genistifolia) and/or Cassinia arctuata (Chinese Scrub). The overlaying ground layers dominated by tussock-forming grass species, with a variety of herbs and forbs found within the interstices (i.e. gaps between tussocks)(Hamilton 2001).

Other common understorey species currently include Gorse Bitter-pea (Daviesia ulicifolia), Guinea-flowers (Hibbertia spp.), Parrot-peas (Dillwynia spp.) and Slender Rice-flower (Pimelia linifolia ssp. linifolia).

The Grey Box woodland occupies areas of Brown duplex soils. Grey Box is the dominant overstorey species. Species such as Drooping She-oak were likely to have been common, while other species such as White Box and Yellow Box may have occurred irregularly. The composition of the understorey is generally similar to that of the White Box woodland.

There have been 164 species of indigenous plants identified as occurring in the DBR, and 81 species of introduced plants (Hamilton unpublished 1999). Most of the introduced species occur in a relatively low abundance, and most are more abundant around the periphery of the DBR (surrounding land utilised for cropping/grazing), or in areas previously utilised for agriculture.

The DBR contains a significant array of weeds, however the ones that cause the greatest management concern are Horehound (Marrubium vulgare), Spear Thistle (Cirsium vulgare), Paterson's Curse (Echium plantigineum) and European Olive (Olea europeae), the abundance of the latter being an artefact of the extensive Olive groves maintained at the College until the 1970's. The distribution/extent of all of these species is being slowly reduced by continual management effort (Hamilton 1999).

There are 9 endangered, rare, depleted or vulnerable species (Gullan et al.1990) within the precincts of the DBR (Hamilton unpublished 1999), including the Dookie Daisy (Brachyscome gracilis), Slender Tick-trefoil (Desmodium varians), Mallee Pellitory (Parietaria cardiostegia), Australia Piert (Aphanes australiana), Red Bird's-foot Trefoil (Lotus cruentus), and Small Psoralea (Cullen parvum).

While the minimally disturbed sites appear to retain the overall structure of pre-European times, there is no doubt that the current species composition in the understorey, particularly at ground level, is significantly different to the pre-European settlement composition. While no specific regional published information is available, sufficient anecdotal evidence suggests that while all current indigenous understorey species were likely present, e.g. non-tussock-forming grasses, many were much less dominant in the landscape than they are now. The specific example of this is Themeda australis (Kangaroo Grass), which is known to have once been the dominant tussock-forming indigenous species in the area of the DBR (Marshall pers. comm. 1997).

Within the DBR, Themeda australis is still found in a very low abundance. This species requires frequent fire to retain its abundance and dominance (Lunt 1990), and the deliberate exclusion of fire from the DBR since European settlement has led to the observed decline in the species abundance.

In general terms, fire within the Box and Ironbark woodlands in south-eastern Australia in pre-European times was clearly more frequent and widespread due to Aboriginal burning management, and most plant species exhibit adaptations to fire (Environment Conservation Council 1997). The exclusion of such frequent disturbance must have changed the species composition of an area such as the DBR, and probably many similar remnants.

An additional problem is that on the few occasions where low intensity autumn fuel-reduction burning within the DBR has been applied to small areas (< 1.0 ha), the resultant regeneration has led to a complete dominance of introduced annual introduced grasses and daisies (therophytes). No doubt this is due to the surrounding of such areas by productive agricultural land, and the associated continual dispersal of introduced species seed from these adjacent areas.

This implies that a significant seed bank of these seeds exists in the soil through annual dispersal from adjacent areas. If indigenous species seed exists in the soil, then it is either non-viable (Types I and II, Panetta, 1978), or it is being out-competed by the annual introduced species after germination.

The use of low-intensity fire in such situations needs to be considered and planned, and must be evaluated on a site-to-site basis.

It also needs to be considered that at a number of times in the European history of the DBR, Eastern Grey Kangaroos have exerted a major endogenous grazing impact on the vegetation. This is due to over-population of the species as a direct consequence of continued clearance of native vegetation for pastoral/cropping lands, and the provision of enhanced habitat opportunities. There has been no way of specifically isolating the species composition and abundance impacts of kangaroo grazing on the DBR, but there can be no doubt that some changes have occurred as a result.

Fauna

There have been 116 species of indigenous birds, 5 species of amphibians, 15 species of native reptiles, and 26 native species of mammals identified as occurring in the DBR or its environs (Hamilton unpublished 1999).

There have been 4 species of introduced mammals, and 5 species of introduced birds identified as occurring in the DBR or its environs (Hamilton unpublished 1999).

Of the native species, 13 have been classified as having conservation status, a few of which have not been sighted in the DBR for a number of years.

The Squirrel Glider (Petaurus norfolcensis), Barking Owl (Ninox connivens), Brush-tailed Phascogale (Phascogale tapoatafa) and the Proximus Blind Snake (Ramphotyhlops proximus) have all been sighted in the DBR or its environs, and are considered to be rare and restricted in Victoria.

The Bush Thick-knee (Burhinus grallarius), Swift Parrot (Lathamus discolor), Grey-crowned Babbler (Pomatostomus temporalis), Square-tailed Kite (Lophoictinia isura), Bandy Bandy (Vermicella annulata), Regent Parrot (Polytelis anthopeplus), Turquoise Parrot (Neophema pulchella) and Striped Legless Lizard (Delma impar) have all been sighted in the DBR, and are all classified as vulnerable in Victoria (DCE unpublished 1991).

The Regent Parrot observation was likely a "one-off" sighting during the height of a drought, and it is considered an incorrect identification of the Striped Legless Lizard was made in 1992 during a DCE fauna survey in the area. The sighting of the Bandy Bandy was an opportunistic sighting of one individual during a spotlighting tour in 1997 observing Squirrel and Sugar Gliders.

The Regent Honeyeater (Xanthomyza phrygia) has not been seen in the DBR since 1964, and is currently considered endangered in Australia. The sightings of the Grey-crowned Babbler (1991) and the Regent Honeyeater are not in recent times, and the lack of presence is most likely due to the loss of connectivity of the DBR to other bushland areas within the region.

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