Balmattum Nature Conservation Reserve Interim Management Statement

MANAGEMENT CONTEXT

HISTORICAL
The grassy woodlands and creeks of the Riverine Plains were an important source of food and other resources for Aboriginal people. Over thousands of years Aboriginal people managed the land using fire as a means of promoting particular plants and controlling the vegetation structure to favour certain game. This management would have had a significant influence on the ecosystems that were present at the time of European settlement.
Following the explorations of Hume and Hovell and Thomas Mitchell, the fertile plains of this region were rapidly and almost completely settled. Although both sheep and cattle were stocked, sheep grazing generally pre-dominated.
The first settlers in the region recorded areas of “Box” (Eucalyptus microcarpa), “Gum” (Eucalyptus camaldulensis), “She-oak” (Allocasuarina spp.) and “Cherry Trees” Exocarpus cupressiformis. The density of overstorey described varied from “scattered” and “lightly wooded” to “moderately wooded” in these communities (Berwick in prep).
The increasing intensity of agricultural development since settlement has resulted in serious environmental degradation and contributed to widespread salinity, invasion by pest plants and animals, loss of biodiversity and a general decline in ecosystem health in this region.

STRATEGIES & PLANS
Numerous government policies and legislative instruments are of direct relevance to the management and protection of the Reserve. These include the Victorian and Commonwealth Biodiversity Strategies (DNRE 1997; Commonwealth of Australia 1996), the National Reserve System Program, the Draft Conservation Program for Native Grasslands and Grassy Woodlands (DCE 1992), the Draft Goulburn Broken Native Vegetation Plan (Goulburn Broken CMA 2000) and the Box-Ironbark Forests and Woodlands Investigation Draft Report (ECC 2000).
Legislation of relevance to the management of the reserve includes the Flora and Fauna Guarantee Act 1988 and the Commonwealth Environment Protection and Biodiversity Conservation Act 1999. Action Statements required under the Flora and Fauna Guarantee Act have been developed by DNRE for the Grey Crowned-babbler and Bush Stone-curlew.
The Reserve is part of an area identified in the Draft Goulburn Broken Native Vegetation Management Plan as being a high priority for works and a target area for the Catchment Management Authority’s Woodlands and Wildlife project funded through the Natural Heritage Trust.
The Reserve is included in the Natural Resources and Environment/Trust for Nature/CMA Bioregional Planning project that is identifying strategic areas for works using a focal bird species approach for the Riverine Plains and Inland Hills of the Goulburn Broken catchment.
It is in the project area for the CMA/CSIRO Heartlands project that includes funding for on-ground experimentation and habitat protection works.
The Reserve is also a key location for the Birds Australia Grey-crowned Babbler Project as it provides the nexus between two larger populations at Molka and Sheep Pen.

PAST MANAGEMENT
To some extent one can surmise the past landuse of the Reserve by the current condition of the vegetation. It is likely that there was considerable tree regeneration following European settlement and the subsequent cessation of burning by Aboriginal people. Many of the large number of stumps on the Reserve are likely to be from this regeneration which was subsequently cut for firewood or cleared in the 1920s and 1950s. There are a large number of young River Red Gums in parts of the reserve from

episodic flood events in the last 25 years. In the past decade a small number of large trees have been removed from the northern end of the Reserve as evidenced by mounds of disturbed soil and some fallen trees.

The land was used for low-intensity sheep grazing for many years prior to 1997 when all stock were removed. It is likely that the heavy soils precluded heavy grazing. Since 1997 there has been no stock- grazing on the reserve apart from the occasional animal straying from adjoining properties.
One section of the Reserve adjoining the southern boundary (about 10 ha) has been completely cleared and sown patchily to rye and clover. The remainder of the Reserve has, in all probability, not been ploughed, sown down nor had fertiliser added for many decades.
Unused road reserves adjoining Balmattum Reserve have, in general, experienced lower levels of disturbance. All areas would have been grazed by stock, kangaroos and rabbits to some extent but they generally retain a comparatively higher level of tree cover with little evidence of clearing.
The Old Euroa Road retains an excellent overstorey of Grey Box, River Red Gum and White Box with some shrubs and a relatively rich understorey. The road reserve has been subject to intermittent fuel reduction burning and to occasional episodic grazing (mostly through stock movements by local landholders).

VEGETATION RESPONSE TO MANAGEMENT
A number of authors have cautioned that stock grazing may be detrimental to the maintenance of conservation values within grassy woodland communities, either as a continuous management practice or in dry seasons (Moore, 1964; Lunt, 1991; McIntyre et al 1993; Prober & Thiele1996; Barlow 1998). However, maintenance of low intensity grazing may be a strategic management course to maintain existing conservation values (Fensham 1991; Barlow 1998; Lunt et al 1999). It is noteworthy too that the present floristic composition of native grassy remnants is profoundly influenced by recent and historical management (Lunt 1995; Foreman 1996).
As a general statement, continuous grazing results in changes to species composition of native grasslands favouring C3 grasses (commonly called winter-growing or cool-season grasses) over C4 grasses (summer-growing, warm-season grasses), short-growing species over tall, introduced species over natives and annual species over perennials. Low intensity or selective grazing pressure may remove highly palatable species such as native peas (e.g. Swainsona spp.), daisies (e.g. Microseris scapigera), orchids and lilies from the vegetation altogether (Davies 1997) and may prevent regeneration of woody species (Lunt et al 1999).
Cessation of grazing may have short-term effects of promoting a ‘flush’ of heavy growth from species such as *Anthoxanthum odoratum, *Avena spp., *Cirsium vulgare, *Holcus lanatus, *Phalaris aquatica and *Picris echioides. Over a longer time-frame of ten years, Lunt and Morgan (1998) found that there were considerable changes in plant composition in a fertile open native grassland at Derrimut following the change from a basic grazing regime to one of mosaic burning. The major change was the increase in tall forbs with windblown seeds (mostly thistles). In the absence of any biomass removal either by fire or grazing, tall perennial grasses are likely to dominate the vegetation with a consequent reduction in species diversity.
The interaction of burning and on-going grazing has been poorly studied in grasslands and grassy woodlands. Leigh and Holgate (1979) note that fire predisposes grassy communities to increased grazing from both marsupials and stock, which may impose additional physiological stress on recovering plants, especially more palatable species.
Kangaroos may exert considerable grazing pressure in grassy woodlands and can be highly selective grazers with a pronounced preference for monocots (Robertson 1985). They tend to avoid grazing on herbs and woody plants where fodder is plentiful. High numbers of kangaroos can severely degrade vegetation and prevent regeneration of native woody species (Cheal 1993). Kangaroos will also avoid feeding on rank growth and thus maintain a low open grass cover in areas favoured for grazing.
The contrast between vegetation on the adjoining Old Euroa Road and the Reserve is a stark indication of the effects of tree clearance and continuous stock grazing on native vegetation communities. The

heavy seasonally inundated soils that occur across much of the Reserve may have meant that the usual grazing pressure was relatively low. Nevertheless, it is clear that the natural shrub layer has been totally removed, the number of trees across the site as a whole has been significantly reduced and tree regeneration was prevented by past stock grazing. In addition a comparison of the ground flora of the roadside and the Reserve indicates that the composition and structure has been altered and its diversity and richness considerably reduced.

Since grazing was removed in 1997, the composition and structure of the vegetation has changed to some extent. Along with considerable regeneration of trees, there has also been some improvement in the condition of the understorey. The first biological survey of the property (Robinson & Mann 1999) recorded 53% cover of weed species in the spring of 1998. On re-inspection in spring 1999 this cover was of the order of 35% with the majority of this due to introduced annual grasses. Not all changes are beneficial, however, and in many areas where the natural tree cover has been removed, the removal of stock grazing has resulted in a dense cover of grasses (both native and introduced) to the probable detriment of native forb species.
At present vegetation within the Reserve can be generally categorised into three main “classes”:

1. 
   Relatively Intact
   

Relatively intact vegetation is found in patches throughout the Reserve but is generally concentrated in the central area and on the eastern and western fringes. This class includes areas that have active tree regeneration and a relatively rich understorey. It includes areas of Plains Grassy Woodland and Plains

Grassy Woodland/Gilgai Wetland Mosaic and areas dominated by either Eucalyptus camaldulensis or

Eucalyptus microcarpa. There is a consistent but relatively low cover of native grasses and moderate to high flora and fauna values. The shrub layer that would have been part of these woodland communities has been completely removed through the effects of stock and rabbit grazing. Trees have been thinned or removed from within these areas and most mature trees are of reasonably consistent age.
It is assumed that the relatively open ground cover and successful regeneration of overstorey species will continue in the continued absence of stock grazing. These areas also include most of the large old trees on the block.

2. 
   Moderately Intact
   

This class includes Plains Grassy Woodland areas that have had much or all of the overstorey removed and Plains Grassy Woodland/Gilgai Wetland Mosaic areas on heavy soils where the overstorey has been completely removed. Most of these areas have a high cover of grasses (both native and

introduced) and moderate flora and fauna values. Native forbs may be locally common and some

‘microwetlands’ in these areas are in good condition. There is little, if any, tree regeneration. The shrub layer that would have been part of these woodland communities has been completely removed through the effects of stock and rabbit grazing.
Moderately disturbed vegetation is found generally surrounding the central woodland area and in patches throughout the Reserve.

3. 
   Severely Disturbed
   

This class includes those sections where the understorey is overwhelmingly dominated by introduced species including those parts that have been ploughed. These areas have a high cover of grasses especially introduced species, high cover of weeds and low flora and fauna habitat values. Few native

forbs are present. The shrub layer that would have been part of these woodland and creekline

communities has been completely removed. There is no active tree regeneration in these areas.
Severely disturbed areas occur along the western half of the southern boundary, in the shearing-shed block and along the northeast drainage line.


Plains Grassy Woodland with good regeneration of River Red Gum and Grey Box and with an open understorey following four years of stock exclusion.

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