Issue: Conserving biodiversity in Tumut Shire

| Assessment | Implications | Recommendations/Objectives to be achieved |
| Background | Indicators used to assess this issue |

Foreword

Three biogeographic regions are represented in Tumut Shire—almost half the Shire falling within the South-Eastern Highlands bioregion, around one-eighth in the Australian Alps bioregion and the remainder (in the north-west of the Shire) is at the extremity of the NSW South-Western Slopes bioregion. For this reason, Tumut Shire stands alone as the West sub-bioregion, and it is not grouped with any of the other sub-bioregions developed to help discuss this issue.

Tables 1, 2 and 3 provide summary data of Indicator results (and the basis for an assessment of biodiversity conservation within the sub-bioregion). Where an indicator is not mentioned in the tables, that omission suggests that either the Indicator is not significant, or the Indicator has insufficient information about it to provide a current assessment.

Assessment

The main threats to biodiversity in Tumut relate to human activities in the broad valley floors and undulating hills. Pressures such as land use and pest plants are continuing to have a negative impact on residual biodiversity levels of native grassy and grassy woodland ecosystems after over one hundred years of human impact.

As the most threatened grassy ecosystems have less than 10% of their pre-1750 levels remaining, this current level is well below the 40% threshold of the pre-1750 area (See: Implications). The small fragments of remnant ecosystems, with a high proportion of edge length to core area, are also more susceptible to change from external and internal pressures and stressors.

By contrast, many of the ecosystems in the less fertile and more dissected terrain of the Tumut area are relatively intact. The high mountain plateau and ranges of Tumut Shire in the extensive reserve network have low to moderate threats in the short to medium term. The main issues in the management of these areas will be ongoing control and management of pest animals, pest plants and fires.

In the longer term, issues relating to climate change may become more significant for ecosystems at alpine and sub-alpine zones.

Specifically in relation to Tumut Shire, progress has been made towards better biodiversity conservation since the 1997 State of the Environment Report.

Most of that part of Tumut Shire that lies within the South-Eastern Highlands biogeographic region is either within the Kosciuszko National Park or is under management by NSW State Forests. The total area under International Union for Conservation of Nature and Natural Resources (IUCN) categories I-IV in the Shire is around 123 800 hectares or about 33% of the Shire. (Tumut Shire has a total area of some 375 200 hectares.) (IUCN categories I-IV include Strict Nature Reserves, Wilderness Areas, National Parks, Natural Monuments and Habitat and Species Management Areas, and are explained further in Managing biodiversity.) In addition, around 33 000 hectares are informally protected on Crown lands in the Shire (IUCN category V).

Up to 58% of the Tumut Shire, or 227 492 hectares, had been cleared or modified by 1997, having a substantial impact on the terrestrial native biodiversity within the Shire, particularly in the lower slopes of the Shire's hillsides. Since the start of this reporting period in 1997, only a further 15 hectares on private land were approved for clearing—which is negligible compared to historical clearing rates .

With something like 22% of the Shire used for both native and pine forests, most of the activity between 1990 and 1995 (and probably since then) was in regard to forestry landuses. Satellite imagery shows that almost 3800 hectares were cleared for forestry purposes from 1990–95, representing more than 90% of the vegetation clearing in the Shire in that period. Nearly 1400 hectares were (re)planted. The interpretation does not distinguish whether the clearing was pine or native forests.

Information about aquatic biodiversity is limited to research of aquatic macro-invertebrates under the AUSRIVAS program. In the Tumut Shire, the program reported that five of eight AUSRIVAS sites—all in the Murrumbidgee catchment—showed minimal human impact. These results suggest that the ecological health of the river systems at those sites is good. The Yarrongobilly River at Ravine, and the Goobarragandra River at Kell Road, however, were considered to be only in 'fair' condition, and the Tumut River at the Snowy Mountains Highway is assessed as being in 'poor' condition.

The Booroolong Frog Litoria booroolongensis which occurs in Tumut Shire was declared endangered during the reporting period, and the status of the Swift Parrot Lathamus discolor was changed under the NSW Threatened Species Conservation Act 1995 from vulnerable to endangered. The number of threatened fauna species in the Shire was listed as 31 at the end of the reporting period, and includes five nationally endangered species, and six nationally vulnerable species.

At the end of the reporting period at least five flora species which are declared endangered or vulnerable under the NSW Threatened Species Conservation Act 1995 were listed in the NSW National Parks and Wildlife Service Wildlife Atlas as occurring in the Shire. Three of these are also nationally vulnerable. However, the list of threatened flora and fauna species within the Shire needs to be confirmed with National Parks and Wildlife Service, as our previous report noted at least four more threatened flora species as occurring in the Shire, one of which is the Tumut grevillea Grevillea wilkinsonii. Two of those species are also nationally endangered, and two nationally vulnerable. In addition we need to be able to list those threatened species that exist in Council-managed areas. Such information needs to be put into Council's planning documentation to enable more responsible management by Council for threatened species.

The conservation of the Shire's biodiversity has been further attended to by the completion of national recovery plans for the endangered Regent Honeyeater Zanthomyza phrygia and the Striped Legless Lizard Delma impar, whilst at the State level, a draft plan has been completed for the Southern Corroboree Frog Pseudophryne corroboree and the Smoky Mouse Pseudomys fumeus. Plans are in preparation for a further six species—Green and Golden Bell Frog Litoria aurea, the Brushtailed Phascogale Phascogale tapoatafa, the Koala Phascolarctos cinereus, the Squirrel Glider Petaurus norfolcensis, the Southern Brown Bandicoot Isoodon obesulus and the Yellow-bellied Glider Petaurus australis..

The NSW Comprehensive Regional Forest Assessment process occurred from 1997–2000 and generated new data on vegetation ecosystems which have been reported in detail under Ecosystem diversity. The analysis of new vegetation data initially suggests that of some 39 vegetation ecosystems in the Tumut Shire, 10 were assessed as 'highly dysfunctional' and a further three were assessed as 'dysfunctional'. (These assessments were based largely on the extent of modification and clearing since European settlement, and the analysis is explained in results for Ecosystem diversity.) That leaves 26 vegetation ecosystems that were assessed as either 'functional' (14) or 'moderately functional' (12), largely because of their relative intactness and limited human impact.

Further analysis (detailed in results for Managing biodiversity) looked at the extent to which the various vegetation ecosystems in the Shire, particularly those that have been heavily modified, are adequately represented within dedicated reserves. Nineteen vegetation ecosystems were assessed as adequately represented, of which 17 are considered to be in some way 'functional' and two are considered to be 'dysfunctional'. That leaves 20 vegetation ecosystems that occur in Tumut Shire that are inadequately represented in the dedicated reserve system, and 11 of these are already 'at risk' because of the extent to which they have been modified since European settlement. Subject to verification of the analysis, those vegetation ecosystems require immediate protection and/or restoration. They are listed below:

• 43—Western Slopes River Red Gum Riparian Moist Sedge Woodland
• 160—Central Highlands Blakelys Red Gum-Yellow Box Dry Grass Woodland
• 161—Tablelands and Slopes Yellow Box Dry Herb-Grassy Woodland
• 154—Tablelands Apple Box Dry Grassy Woodland
• 117—Western Slopes White Box Dry Grass Woodland
• 120—Western Slopes Red Stringybark-White Box Dry Shrub-Herb-Grassy Forest
• 116—Western Slopes Blakely's Red Gum Herb-Grassy Woodland
• 148—Tableland Swamp Tussock Grass-Carex Grassland /Sedgeland/ Open Woodland
• 118—Western Slopes Red Ironbark-Red Box Dry Grass Forest
• 119—Western Tablelands Red Box-Red Stringybark Dry Shrub/Grass Forest
• 94—South West Slopes Red Stringybark-Apple Box Acacia Dry Herb-Grassy Forest

Note: the number refers to the identifier used for analysis of all the ecosystems across the region

In considering conservation of the above 'dysfunctional' vegetation ecosystems, it should also be noted that some woodland birds are under threat as a consequence of habitat loss. Three species that occur within Tumut Shire and are considered to be in decline are the Diamond Firetail Stagonopleura guttata, Speckled Warbler Chthonicola sagittata and Varied Sittella Daphoenositta chrysoptera.

During the reporting period 1997–98 to 1999–2000, actions to support/reinstate biodiversity in the Shire under the Natural Heritage Trust included recovery planning for the Corroboree Frog and the Southern Corroboree Frog (under the Endangered Species Program) and several other projects. On-ground work included preservation of Grassy White Box Woodlands in conjunction with other Shires, under the Bushcare Program, and erosion control and wildlife habitat by Gilmore Landcare Group, under the National Landcare Program.

Weed infestation continues in the Shire as a threat to both biodiversity and agriculture. A Roadside Vegetation Survey and Management Guidelines were developed in March 1997. A management strategy has been developed for the control of seven weeds under the Guidelines. They are St. John's Wort Hypericum perforatum, Blackberry Rufus fruticosus, Paterson's Curse Echium spp, Illyrium Thistle Onopordum illyricum, Scotch Broom Cytisus scoparius, Sweet Briar Rosa rubiginosa and Bathurst Burr Xanthium spinosum. Control activities include complete eradication for such as Illyrium Thistle, but reducing or stopping the spread of others, particularly along roadsides and other Council-controlled land. Sweet Briar, Blackberry and St John's Wort are all reported as environmental weeds, which thrive in National Parks and State Forests and therefore have a greater impact on native biodiversity than those weeds which invade agricultural lands.

There is little information about the impact of pest animals on biodiversity in the Tumut Shire. Pest animals found in the Shire are controlled by Gundagai Rural Lands Protection Board under a Vertebrate Pest Plan (1999), in conjunction with landholders and community groups such as Landcare. (The Rural Lands Protection Board is responsible for pest animal control through all agricultural lands and Travelling Stock Routes) in the Shire. National Parks and Wildlife Service and State Forests control pest animals species on lands under their control under separate management plans.

Coordination of group baiting of wild dogs is apparently effective in Goobarragandra Valley, with losses of sheep dropping from 200-300 a year five years ago, to losses of only 40 sheep in 1999. Wild dogs are mostly confined to Kosciuszko National Park and State Forest boundaries. Impacts on native fauna of wild dogs are not known.

Populations of feral pigs, also mostly restricted to National Parks and State Forests and their fringes, are static as a result of controls and landholder education coordinated by Rural Lands Protection Board rangers.

Deer populations are said to be increasing in National Parks but no control program is in place.

Rabbit numbers and density have reduced by around 30% over the last five years, as a result of Rural Lands Protection Board activities. (Populations are most dense in Gilmore Valley, Goobragandra Valley and Wondalga.)

A Bush Fire Risk Management Plan is in preparation. A Regional Vegetation Management Plan (under the Native Vegetation Conservation Act) is being drafted at the time of writing, which examines the ecological requirements for various threatened species. Various fauna and flora species listed under the Threatened Species Conservation Act 1995 have either been recorded, or have a habitat preference which matches components of the Tumut district environment. Knowledge of the fire ecology of these species is incomplete, and requires further study. There was no information available for this report about fires during the reporting period.

Around 70% of the Shire is native grassland, cleared for agriculture, or it is dry forest. As a result, grassfires pose a threat to native grassland communities and their species, as well as leaving the ground bare and susceptible to erosion.

Implications

General implications

Findings of the analysis of vegetation extent, condition and adequacy of representation within the dedicated reserve system must not be taken as fixed and final. They need to be verified on the ground. This is especially true for those vegetation 'ecosystems' that have been provisionally identified as 'highly dysfunctional' (that is, have suffered most disturbance or modification, and are most threatened and least protected), and more particularly, for those listed earlier in this Issue. Verification is needed to confirm the Regional analysis of ecosystems at the local level.

As yet there is no agreed definitive threshold of habitat loss that leads to biodiversity decline, as other criteria must also be taken into account in assessing decline, or potential decline, in biodiversity. A mix of minimum retention percentage, minimum patch size and minimum width of connective links has been suggested.

According to Smith et al (2000), 'The study of critical thresholds of habitat loss is a new and rapidly developing field ... Generally, at low levels of habitat loss, the decline in biodiversity is approximately proportional to the area of habitat lost (Andren, 1994). As the amount of habitat loss increases there appear to be thresholds beyond which biodiversity decline accelerates and then becomes very rapid. These thresholds are difficult to delineate and are likely to vary between differing landscapes ... In landscapes where less than 30% of the original habitat remains, species loss is particularly rapid (Andren 1994, 1997, With 1997) ...' It should be noted that these estimates are based on northern hemisphere studies.

The paper by Smith et al, prepared for the Native Vegetation Advisory Council of NSW, goes on to say that in Australia, where the climate is generally more erratic and the environment more complex, it is possible that the effects of fragmentation could be felt at much lower levels of clearing.

In the current analysis, the limit of 40% of original cover in the dedicated reserve system has been used as the cut-off point for adequate-inadequate representation, although the NSW Comprehensive, Adequate and Representative reserve system has adopted a more stringent criterion of 15% of the areal extent of the pre-settlement distribution, for adequate conservation of any particular vegetation community. The vegetation ecosystems in Tumut Shire where both less than 15% and less than 40% of the original cover has been conserved have been tentatively identified.

To ensure habitat loss does not extend beyond that threshold—or another agreed threshold—it will be important in some cases to include habitat that occurs outside the conservation system, particularly where that habitat provides a critical connective link. In this regard, it will be important for member Councils of the Australian Capital Region to ensure Region-wide protection of vegetation communities which are under threat.

It will also be important for Council to work with NSW National Parks and Wildlife Service and other relevant bodies to confirm information on threatened species that occur in the Shire, in particular, within that area managed by Council.

Valley floors and undulating hills of Tumut Shire

Pending verification of the analysis, and consistent with the CAR system adopted by the NSW Government, ecosystems with less than 15% of their pre-1750 area in a conservation network need to have greater protection. These ecosystems are listed in the managing biodiversity sections of each local government area.

Detailed assessment of under-represented ecosystems needs to address how best to create a conservation management network on both public and private lands within each local government area. A conservation management network should incorporate the following:

• a range of conservation mechanisms, including legislative protection, land use planning, conservation agreements on private land, with incentives and mechanisms for conservation
• integrated ecosystem management plans for each reserve and for all potential corridors, that incorporate:
• management regimes (including monitoring) to restore structural diversity of degraded habitats
• information on bushfire, weeds, and ecological states of ecosystems, to enable more effective and strategic management of ecosystems and the species they contain.

Aquatic macro-invertebrate diversity may be due to run-off after heavy rainfall events, landuse and landuse change. Further investigation is required and actions taken to restore river health where necessary.

Decline of native bird species in fragmented native vegetation needs to be arrested through ecosystem restoration of habitat structure. Follow up monitoring programs of recovery of native bird species should accompany any restoration.

High mountain plateau and ranges of Tumut Shire

More detailed reporting and monitoring of target pest animal species and their impact on native prey species is needed before the next reporting period.

Detailed assessments of current fire regimes for all ecosystems should be reported in digital GIS formats, against known historical fire regimes to determine the extent of current deviation from historical conditions.

Recommendations/Objectives to be achieved

That Council:

1. cooperate with other Councils in the Region and relevant State agencies to (1) verify the extent and condition of native vegetation communities, in particular, those that are indicated as having less than 40% of their original (pre-1750) extent remaining; to (2) verify the threatening processes associated with those vegetation communities; and to (3) apply this knowledge to establish priorities for the conservation management network within Tumut Shire, and for the Australian Capital Region as a whole
2. maximise efforts to conserve biodiversity in the Australian Capital Region and the Tumut Shire, with a particular focus on off-reserve conservation (Council-managed land)
3. exert maximum influence to ensure detailed assessments of current fire regimes are reported for all vegetation types in digital GIS formats, against known historical conditions
4. exert maximum influence to ensure all threatened species that occur within the Shire, in particular, within Council-managed land, are identified and their habitat and location incorporated into all relevant management and planning documentation.
5. exert maximum influence to obtain more detailed reporting and monitoring of target pest animal species and their impact on native prey species

Background

Fundamental to the concept of biological diversity (biodiversity) is the number and variety of individual ecosystems and species and of the ecological circumstances in which they live. Changes in the conditions of different ecosystems and the number and/or abundance of species within them, are the most obvious factors that warn of possible changes in biodiversity.

Knowledge for the long-term survival of biodiversity is dependent upon continual assessment at the two key levels of biodiversity—that of native species and ecological communities. The provision of reliable data on species populations and their ecological function within identified ecosystems is a fundamental prerequisite to the management and conservation of biodiversity within landscapes. High quality research and monitoring, supported by appropriate legislation, funding, and cooperative mechanisms, is fundamental for thorough and adequate preparation and implementation of protection and recovery plans.

Indicators used to assess this issue

References:

Andren, H (1994) Effects of habitat fragmentation on birds and mammals in landscapes with different proportions of suitable habitat: a review, Oikos 71:355–366.

Andren, H (1997) Habitat fragmentation and changes in biodiversity, Ecological Bulletin 46:171–181.

Smith, PL, Wilson, B, Nadolny, C, Lang, D (2000) The Ecological Role of The Native Vegetation of New South Wales, Background paper number 2, Native Vegetation Advisory Council NSW, Department of Land and Water Conservation.

Thackway, R and Cresswell, ED (1995) An Interim Biogeographic Regionalisation for Australia: A Framework for Setting Priorities in the National Reserves System Cooperative Program, Version 4.0 Australian Nature Conservation Agency, Canberra.

With, KA (1997) The application of neutral landscape models in conservation biology Conservation Biology 11:1069–1080.