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Goulburn Broken Catchment Management Strategy

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Regional Catchment Strategy 2013-2019

Biodiversity

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Biodiversity is the 'variety of all life forms – the different plants, animals and micro-organisms, the genes they contain and the ecosystems of which they form part' (DSE 2012).  Biodiversity underpins the health of connected natural and managed systems and provides ecosystem services that humans cannot imitate at large scales (Straker and Platt 2002; CSIRO 2003). 

Biodiversity as an asset can be broken into further sub-catergories including native vegetation, wetlands, rivers and streams, native fauna and soil biodiversity (GB CMA 2010) .  For the purposes of the RCS, the assets considered in the biodiversity section of this supplement will be terrestrial habitat; and threatened species and communities.  Wetlands, rivers and streams are considered in the Water section and soil biodiversity in the Land section.

Terrestrial habitat includes native vegetation as well as rocky outcrops, fallen timber and soil. Native vegetation occurs as remnants, linear patches (e.g. roadsides), revegetated sites and large reserves (Figure 3.1). Native vegetation provides a range of ecological, social and economic values including the provision of habitat for the majority of species.  In fragmented landscape, native vegetation provides linkages to ensure species movement, which is important in gene flow and the ability of species to adapt to change (Coulon et al 2010; Lowe and Allendorf 2010).

There are several terrestrial habitat types and important conservation areas found across the Goulburn Broken Catchment. These include:

  • Box Gum Grassy Woodlands of the Riverine Plains
  • Red Gum woodlands, including Barmah Forest.
  • Buloke remnants of the plains
  • Herb Rich Forests of the Warby Ranges
  • Box Ironbark Forests of Reef Hills State Park and Whroo Goldfields parks.
  • Spring-soak wetlands and rocky outcrops of the Strathbogie Ranges
  • Grassy woodlands of the Dookie and Chesney Hills
  • Remnants associated with waterways
  • Alpine Rocky Outcrops, fens and bogs
  • Sub Alpine Dry Shrubland

Within these terrestrial habitats there are a number of threatened species and ecological communities. These species and communities are important both for the role that they play in the boarder ecosystem as well as their socio economic value. Some threatened species and communities found within the Goulburn Broken Catchment that are identified in the RCS as being of focus in one or more of the SESs include:

  • Superb Parrot
  • Bush-stone Curlew
  • Squirrel Glider
  • Grey -crowned Babbler
  • Swift Parrot
  • Regent Honeyeater
  • Legless Lizard
  • Golden Sun-moth
  • Crimson Spider Orchid
  • Ant-blue Butterfly
  • Western Rat-Tailed Grass
  • Slender Bitter Cress
  • Creeping Grevillea
  • Matted Flax Lily
  • Barking Owl
  • Powerful Owl
  • Diamond Firetail
  • Specked Warbler
  • Mountain Pygmy Possum
  • Dendy's Toadlet
  • Spotted Tree Frog
  • Growling Grass Frog
  • Brown Toadlet
  • Alpine Tree Frog

Further details on threatened species and communities can be found in the GB CMAs Biodiversity Strategy and biodiversity interactive maps at dse.vic.gov.au.

Current condition

Past and current land management practices have resulted in the loss of much of the Catchment’s native vegetation, particularly in production-focussed areas. Catchment condition reports (VCMC 2007; GB CMA 2012 p.16) rate the Catchment’s biodiversity as variable, from poor to good condition.  This largely reflects the relatively good condition of the Southern Forests SES to the poor condition of biodiversity in much of the rest of the Catchment. Table 3.1 provides an overview of what this rating means. The Catchment condition of poor is based on comparison with pre-European condition. 

 

Near Natural

Ecological Healthy

Sustainable Working

Modified / Degraded

Values

High degree of naturalness, significant species, few threatened species or communities. High diversity.

High degree of naturalness, significant species and high diversity. Some threatened species and communities.

Moderate naturalness, significant species, high levels of threatened species and communities, high diversity but in few places

Low level of naturalness, diversity of species in-situ rare, high levels of threatened species and communities, highly fragmented (relictual), remnants too small for viable communities

Condition

Excellent

Good

Moderate /Poor

Poor/Very poor

Modification

Very Low

Low

Moderate

Moderate to high

Basis

Intact native vegetation cover (>60%),

Intact native vegetation cover (30-60%)

Fragmented native vegetation cover (10 -30%)

Relictual cover of native vegetation (<10%)

Examples

Alpine National Park

Barmah National Park

Longwood/Violet Town Plains

Irrigated farm land or landscapes

Naturalness

Very High

High

Medium

Low-Very Low

Socio Economic Benefit

High

High

High

High

Table 3.1: Biodiversity values and condition of the typical ecological condition states

As the extent of native vegetation varies across the Catchment, so does the area of Ecological Vegetation Classes (EVCs) that are threatened with extinction (Figure 3.1). Sixty four per cent of EVCs in the Catchment are classified endangered or vulnerable (DSE 2007).  The conservation of native vegetation has been, and is still is, in certain areas, in conflict with some human activities (e.g. land clearing for pivot irrigation, logging). Increasing the extent of native vegetation has recently been shown to be the most important action to achieve biodiversity conservation (Bennett et al. 2006; Lindenmayer et al. 2012), while also increasing habitat quality.

  

Figure 3.1: Current modelled tree cover extent expressed as Ecological Vegetation classes

Threatened species are found across the Catchment (Table 3.2). There are 2,750 native plant species, of which 337 (13 per cent) are threatened, and 493 vertebrates, of which 110 (43 per cent) are threatened (see Appendix two Goulburn Broken CMA Biodiversity Strategy). Some species that once occupied the Catchment are now extinct, such as the Eastern Bettong. Many threatened species now persist only in small patches of remnant habitat dominated by human influences (Bennett et al 2006).

Threat Category1

Birds

Mammals

Reptiles

Amphibians

Fish

Total

Regionally Extinct

0

2

0

0

1

3

Critically Endangered

5

2

0

3

3

13

Endangered

13

3

4

2

3

25

Vulnerable

23

4

1

1

2

31

Data Deficient 

0

2

2

1

2

7

Near Threatened

25

4

2

0

0

31

Total Threatened

66

17

9

7

11

110

No. of native species in catchment

298

70

72

31

22

493

No. of introduced species in catchment

13

14

0

0

8

35

Table 3.2: Number of taxa by class and Victorian Conservation Status Category of fauna in the Goulburn Broken Catchment (DSE 2007 and Victoria Fauna Database)

Significant threats

In 2009 the Goulburn Broken CMA undertook a risk analysis to identify the important risks to biodiversity across the Goulburn Broken Catchment, with a particular focus on risk posed by climate change (Brunt and Miles 2009). The assessment identified a significant number of extreme threats to biodiversity as outlined in table 3.3.   Many of these extreme threats result from or relate to, one or more of the four drivers of change identied in the RCS, however the assets and threats with the highest number of extreme risks (shaded in grey in table 3.3) suggest that the greatest threats relate to land use change (reduced habitat function, isolation and simplification and weed invasion) and climate variability.   While at the time of the assessment, saline water and high water tables were deemed to be less threatening because of reduced rainfall, the swing back to higher rainfall, could again see salinity again pose a major threat to biodiversity, especially in the context of other multiple threats.

Table 3.3:  Summary of extreme (E) risk across broad biodiversity assets in the Goulburn Broken Catchment (GB CMA 2010).

Notes to table: threats in italics are 'induced threats'.  Standard text generally refers to land and water use practices, including in new areas. Those threats in red are 'natural' processes now potentially more serious because the environment has been modified).  The yellow section highlights climate change threats.  Assets and threats with a high number of extreme risks are shaded in grey. 

While the drivers of change identified in the RCS pose risks to biodiversity assets in the Catcment, they also provide opportunties.  For example natural regeneration is occurring as land-use moves from traditional farming to lifestyle (e.g. in the dry box-ironbark forests) and this type of vegetation has been shown to have biodiversity benefits (eg Lunt et al. 2010).  Further detail on the relationship between assets and the drivers of change can be found in each SES description in the RCS.

Management

It is not feasible, possible or desirable to return the Catchment to pre-European condition as the social and economic systems important to the resilience of the Catchment would not function under these conditions.  There is however some evidence that increasing native vegetation extent to approximately 30 percent, in landscapes where there is less than this, may be enough to create functioning landscapes, increase species diversity and richness (Radford et al. 2002), increase production (Straker and Platt 2002) and improve waterway health (Lefroy et al. 2012).

Across the Catchment, significant investment is made to protect and restore biodiversity assets in line with the objectives of the Biodiversity Strategy for the Goulburn Broken Catchment, Victoria 2010-2015 (the' Biodiversity Strategy') (GB CMA 2010).  Projects and activities are undertaken by a broad range of organisations, including DSE, DPI, Trust for Nature, Local Government, Yorta Yorta Nation Aboriginal Corporation (YYNAC), Taungurung Clans Aboriginal Corporation (TCAC) and community-based Natural Resource Management groups in the protection of biodiversity assets.   

Many communities have identified biodiversity assets in their local area and are working as individual landholders and/or collectively to protect and enhance these assets on both public and private land through activities including regeneration and revegetation and weed management. Community groups including Landcare, Conservation Management Networks, Committees of Management of Crown Land and community initiatives including the Superb Parrot  and Regent Honeyeater Projects, all have a proud history across the Catchment in harnessing funding and community participation to protect and enhance biodiversity assets.

Guiding current thinking

The Biodiversity Strategy for the Goulburn Broken Catchment, Victoria 2010-2015 outlines key management measures for how long-term biodiversity objectives will be met. This strategy sets the 20-30 year strategic objectives for biodiversity of the Catchment, including the rationale for the objectives and how they will be achieved.  

Key policies and strategies that guide the identification and protection of threatened species and communities are the State Flora and Fauna Guarantee Act 1988, Commonwealth EPBC Act 1999 and the State Native Vegetation Framework 2002, as well as state and federal policies which guide the ways in which funding for biodiversity is distributed.

Asset identification and prioritisation

Priority biodiversity assets at the Catchment scale were identified during the development of the Biodiversity Strategy through an assessment process that included consideration of existing biodiveristy attributes and the potential to contrubite to ecological objectives.  Local and expert knowlege was used to asses and weight biodiversity values and objectives, enabling a prioritisation process across 14 geographical zones to be undertaken and represented spatially (GB CMA 2010).     At a statewide level, Natureprint has been developed based on species distribution and other models to inform the identification of priorities.   Figure 3.2 shows the alignment between the spatial priorities identified in the Biodiversity Strategy and Natureprint.

While the two approaches are different, the identification of spatial priorities demonstrates a strong corrolation between the two appraoches. High value zones for protection from the Biodiversity Strategy coincides with high values in Natureprint, and high value zones for restoration and connectivity coincide with moderate values in Natureprint. For example, high value (red) areas for Natureprint are areas recognsied in the Biodiversity Strategy as requiring protection of ecosystem services.  Similarly, moderate to high value areas for Natureprint (dark Green dark purple) are recognised in the Biodiversity Strategy as areas of priority for restoration and improving connectivity.   There are of course, priorities and important assets at finer scales, and landscape and site level priorities within these broader areas require identification and appropriate management intervention (eg wetlands and remnants that connect to the rivers within the 'low' priority areas of the Riverine Plains).

Figure 3.2: Goulburn Broken Biodiversity Strategy and Natureprint asset prioritisation alignment

Threatened species prioritisation

The objective of threatened species management is to increase the numbers of animals and plants of a particular species so that populations are self-sustaining, resilient and able to adapt to change. There is a need for effective decisions to achieve the balance between ‘saving’ threatened species while also preventing more common species becoming threatened. Mostly, management interventions revolve around increasing habitat elements required by specific species or groups of species, and this in turn requires research to understand their distribution and habitat requirements. However, in most instances there is not the luxury of time in which to 'save' species based on a full knowledge set, so the appraoch is often to undertake habitat improvement to provide more resources for a range of species. This improvement can include reducing habitat fragmentation through revegetation (for example Grey-crowned Babblers will not fly between habitat where the gap is greater than 200m), erecting nest-boxes (to compensate for the lack of large-old trees that provide hollows) and enhancing native vegetation remnants through reducing weed invasion.

A prioritisation process can aim for:

  • functioning ecosystems, which are important to maintain all species (threatened, near-threatened and secure),
  • conserving as many threatened species as possible by shifting their status towards secure.

The guiding principles for managing threatened species are:

  • To increase the security of threatened species and communities by targeting key threats.
  • To work with partner organisations to increase knowledge about the management needs of these species.
  • To ensure that the decision-making process for managing threatened species and investment is inclusive, transparent and effective.