Southern Highlands Shale Forest and Woodland of the Sydney Basin Bioregion draft description of the ecological community



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Southern Highlands Shale Forest and Woodland of the Sydney Basin Bioregion

  1. DRAFT Description of the ecological community


The Southern Highlands Shale Forest and Woodland of the Sydney Basin Bioregion ecological community is dominated by eucalyptus trees and typically has a herbaceous understorey, but is rather variable in vegetation structure, ranging from a tall wet sclerophyll forest to a more open, grassy woodland. It occurs in the New South Wales Southern Highlands and is primarily associated with soils derived from Wianamatta Shale.

    1. Name of the ecological community


The Southern Highlands Shale Forest and Woodland of the Sydney Basin Bioregion ecological community (hereafter referred to as the ‘Southern Highlands Shale Forest and Woodland’ or ‘the ecological community’) encompasses the similarly named ecological community ‘Southern Highlands Shale Woodlands in the Sydney Basin Bioregion’ listed under the New South Wales Threatened Species Conservation Act 19951.
    1. Location and physical environment


The Southern Highlands Shale Forest and Woodland is endemic to New South Wales, occurring within the eastern part of the Sydney Basin IBRA bioregion.2

The ecological community occurs on the Southern Highlands plateau, typically associated with clay soils derived from Wianamatta Group shales. The Southern Highlands Shale Forest and Woodland occurs in the Wingecarribee Shire (boundaries as definienda at January 2015), although outliers may occur in adjacent local government areas. The eastern limit of the ecological community is the Illawarra escarpment where Wianamatta Shale is replaced by other geologies (younger basalts and older sedimentary geologies of the Hawkesbury, Narrabeen and Illawarra Groups), Kangaloon, Robertson and Fitzroy Falls; its southern limit is the town of Penrose; it extends north as far as Braemar and Alymerton; and west to Canyonleigh, High Range, Berrima and Medway.

The Southern Highlands Shale Forest and Woodland generally occurs in areas receiving an annual rainfall of between 1400mm in the east and 900mm in the western parts of its range. Typically it occurs at elevations of between 550m to approximately 750m above sea level (asl).

    1. Vegetation


The Southern Highlands Shale Forest and Woodland has a tree canopy dominated by eucalypts and a typically herbaceous understorey, but shows some variation in structure and composition in different locations due to: differences in rainfall, topographic shelter, and exposure; the influence of cold air drainage and ponding; and the influences of groundwater and proximate geologies across the distribution of the ecological community. In addition, extensive clearing, grazing, logging, weed invasion, altered fire regimes and changed hydrological patterns have also resulted in variation in form. Reflecting this variation, three ‘forms’ of the ecological community are recognised: ‘tall wet’, ‘typical’ and ‘short dry’.

The ‘tall wet’ form typically occurs in areas with higher rainfall, soil moisture and fertility, and in areas of sheltered topography. The ‘typical’ form occurs in areas of more moderate rainfall and can be further distinguished into three variants: Penrose, Braemar and Bundanoon ridges and exposed slopes. In areas of lower rainfall, more frost and, in some cases, more exposed locations, the ecological community transitions into a ‘short dry’ form.


Canopy

Characteristic canopy species of the Southern Highlands Shale Forest and Woodland that may be found in all forms of the ecological community include: Eucalyptus globoidea (white stringybark), E. radiata (narrow-leaved peppermint) and E. piperita ssp. urceolaris (Sydney peppermint).

In addition to the aforementioned species, the ecological community is also usually dominated by one or more of the following canopy species in each of the three forms:


  • In the ‘typical’ form of the ecological community by: Eucalyptus amplifolia (cabbage gum), and/or E. teriticornis (forest red gum). In addition, the Penrose variant is often dominated by: E. blaxlandii (Blaxland’s stringybark); the Bundanoon variant is often dominated by: Angophora floribunda (rough barked apple) and/or Eucalyptus macarthurii (Paddy’s River box); and the Braemar variant is often dominated by: E. punctata (grey gum) and E. fibrosa (red ironbark), reflecting a stronger sandstone influence. E. pauciflora (snow gum) may also be present but does not dominate a patch.

  • In the ‘tall wet’ form of the ecological community by: Eucalyptus cypellocarpa (mountain grey gum), E. quadrangulata (white-topped box), E. obliqua (stringybark), E. ovata (swamp gum), E. elata (river peppermint), E. smithii (gully peppermint, blackbutt peppermint) and/or E. viminalis (manna gum, ribbon gum).

  • In the ‘short dry’ form of the ecological community by: Eucalyptus dives (broad leaved peppermint), E. rubida (candlebark, ribbon gum), E. mannifera (brittle gum) and E. cinerea (Argyle apple, silver leaved stringybark). Eucalyptus pauciflora may also occur, and while not a dominant species, its higher frequency in this form reflects the increased exposure to frost and lower rainfall.

In all forms of the ecological community, the presence of Eucalyptus eugenioides (thin-leaved stringybark), E. punctata (grey gum), E. fibrosa (red ironbark), E. agglomerata (blue-leaved stringybark) or Syncarpa glomulifera (turpentine) may indicate that the patch occurs near the edge of the shale substrate (and hence the edge of the distribution of the ecological community).

Understorey - Mid layer

Where present, the shrub layer is typically sparse, although it may be locally dense. In areas associated with high groundwater and/or drainage lines, a mid-layer of Melaleuca species, usually M. linarifolia may be locally prominent within a patch. Acacia species may also be prominent in the mid layer, often reflecting a site’s disturbance history. Acacia mearnsii (black wattle), A. melanoxylon (blackwood, black wattle), A. implexa (hickory wattle) and A. stricta (hop wattle) may be locally dominant.



Oxylobium ilicifolium (prickly oxylobium), Olearia microphylla and Melaleuca thymifolia are found in the north eastern parts of the ecological community’s range; in the south west these species are rare or absent and Daviesia ulicifolia (gorse bitter-pea) may be locally common.

Understorey - Ground layer

The ground layer is typically dense and dominated by grasses and other herbs. Typical native grasses in the ecological community include: Poa sieberiana (fine leaved tussock grass), P. labillardieri (river tussock), Themeda triandra (kangaroo grass), Rystidosperma (syn. Joycea) pallida (red-anther wallaby grass) and Microlaena stipoides var. stipoides (weeping grass). Common herbs include: Gonocarpus tetragynus, Veronica plebeia (speedwell), Hypericum gramineum (small St John’s wort), Poranthera microphylla, Pratia purpurascens (whiteroot) and Viola hederacea (native violet).

More sheltered sites and areas with high groundwater and soils of high fertility may be dominated by ferns, sedges and vines in the understorey.

Contra-indicative flora

The following are considered contra-indicative of the ecological community:



  • presence of the following canopy species: Eucalyptus sieberi (silvertop ash), E. sclerophylla (scribbly gum) (and related variants E. racemosa, E. haemastoma) and Angophora costata (smooth-barked apple, Sydney redgum), and/or

  • a mid-layer dominated by Proteaceae and Myrtaceae species.

    1. Fauna


Although there are no fauna species confined only within the Southern Highlands Shale Forest and Woodland, the ecological community supports a diverse range of fauna (Keith, 2004), providing essential resources such as shelter (e.g. hollows, nesting materials, roosting) and food (e.g. nectar from flowers or invertebrate prey). Some fauna may be transient through the ecological community; for instance pollinating birds such as honeyeaters are likely to visit during flowering season, and other animals may use patches of the ecological community as stepping stones to more preferred habitats.

Many insectivorous bats frequent the ecological community, these include Vespadelus spp. (vesper bats), Chalinolobus spp. (wattled bats) and Nyctophilus spp. (long-eared bats). Other mammal species such as Trichosurus vulpecula (common brushtail possum), Petaurus breviceps (sugar glider), Petaurus australis (yellow-bellied glider), Cercartetus nanus (eastern pygmy possum) and Pteropus poliocephalus (grey-headed flying fox) are also found in the ecological community (NSW Bionet, 2014). The vulnerable (EPBC; NSW Threatened Species Act (TSC Act)) Potorous tridactylus tridactylus (long-nosed potoroo) and Phascolarctos cinereus (koala) have been recorded in the ecological community. Species utilising the grassy/shrubby understorey include Macropus and Wallabia spp. (kangaroos and wallabies), Vombatus ursinus (bare-nosed or common wombat), Tachyglossus aculeatus (echidna), and Rattus fuscipes (bush rat) (NSW Bionet, 2014).

Typical woodland birds found in the ecological community include Acanthiza spp. (thornbills), and Eopsaltria australis (eastern yellow robin). Woodland bird species across eastern Australia are declining due to loss, fragmentation and degradation of habitat (Ford, 2011) and as a result many are now identified as threatened under NSW and/or national environmental legislation. Those found in this ecological community include the vulnerable (TSC Act) Petroica boodang (scarlet robin) and Ninox strenua (powerful owl), and the Anthochaera phrygia (regent honeyeater).

Reptiles including skinks, dragons and snakes; and a range of frog species including toadlets and tree frogs (NSW Bionet, 2014) are typically found in the ecological community. These include threatened species such as Heleioporus australiacus (giant burrowing frog) (EPBC, TSC), and Varanus rosenbergi (Rosenberg’s goanna, heath goanna)(TSC).

The ecological community includes invertebrates, which although poorly known, provide ecosystem services such as pollination and are prey for a range of animals including insectivorous birds and bats.


Further details on flora and fauna species and other relevant biology and ecological interactions and processes can be found at Appendices A and B.



    1. Key diagnostic characteristics and condition thresholds


National listing focuses legal protection on remaining patches of the ecological community that are most functional, relatively natural (see the ‘Description’) and in reasonably good condition. Key diagnostic characteristics and condition thresholds assist in identifying a patch of the threatened ecological community, determine when the EPBC Act is likely to apply to the ecological community and to distinguish between patches of different quality. The ecological community may exhibit various degrees of disturbance and degradation. This degree of degradation has been taken into account in developing the condition thresholds.

The key diagnostic characteristics summarise the main features of the ecological community. These are intended to help people identify when the ecological community is likely to be present.

Condition recognises that patches of an ecological community can differ in their quality, and that some patches have undergone sufficient degradation that they no longer provide a trigger for the EPBC Act. Condition thresholds provide guidance on when a patch of an ecological community retains sufficient conservation values to be considered a ‘Matter of National Environmental Significance’, as defined under the EPBC Act. Patches that do not meet the minimum condition thresholds, therefore, are excluded from full national protection, and this effectively means that the referral, assessment and compliance provisions of the EPBC Act are focussed on the most valuable elements of the ecological community.

Although very degraded or modified patches are not protected as the ecological community listed under the EPBC Act, it is recognised that patches that do not meet the condition thresholds may still retain important natural values and may be protected through state and local laws or schemes. Therefore, these patches should not be excluded from recovery and other management actions. Suitable recovery and management actions may improve these patches to the point that they may be regarded as part of the ecological community fully protected under the EPBC Act. Management actions should, where feasible, also aim to restore patches to meet the high quality condition thresholds.



For EPBC Act referral, assessment and compliance purposes, the national ecological community is limited to patches that meet the following key diagnostic characteristics and condition thresholds.

      1. Key diagnostic characteristics

The key diagnostic characteristics of this ecological community are that it:

  • Occurs in the Southern Highlands in the Sydney Basin Bioregion (IBRA v7).

AND

  • Typically occurs on flat or gently undulating terrain at elevations of between 550m – 750m asl on clay soils derived from Wianamatta shale.

AND

  • Is an open forest or woodland dominated by a canopy of eucalyptus trees with a tree density of at least 10 stems per 0.5ha (at least 20 stems/ha) that are at least 50cm in height.

AND

  • Has a ground layer of native grasses and/or other herbs (although it may vary in development and composition).

AND

  • Contains flora species presented in Table A1 of Appendix A and may contain fauna species presented in Table A2.



      1. Condition thresholds

The condition thresholds apply to patches of forest or woodland that meet the key diagnostic features above, and identify them as patches of the ecological community.

The Southern Highlands Shale Forest and Woodland occurs in an area that has been intensively cleared, where much of the native vegetation that remains occurs amongst a heavily modified landscape. The patches that remain are typically small, highly fragmented and have been disturbed to some extent. It is intended that the condition thresholds will exclude the more highly degraded patches on farms and other properties. For instance, those patches that now exist as isolated paddock trees or small, narrow stands of trees over exotic pastures. The condition thresholds also exclude degraded roadside remnants that are small or narrow, or where the native understorey has effectively become lost, and/or the tree canopy is patchy and discontinuous (i.e. <10% cover).

For Southern Highlands Shale Forest and Woodland, categories C and D are considered to be moderate quality condition (moderate condition class) and the minimum thresholds for a patch of the ecological community to be subject to the referral, assessment and compliance provisions of the EPBC Act. Categories A and B are considered the minimum thresholds for a patch of Southern Highlands Shale Forest and Woodland to be regarded as an example of high quality condition (high condition class).
Table 1: Condition categories and thresholds for the Southern Highlands Shale Forest and Woodland

Category and Rationale

Thresholds

For all the categories below, in addition to a minimum projected foliage cover of canopy trees of 10% or more, the trees must have a density of Either

At least 10 native trees per 0.5 ha (=20 trees/ha), that are at least 10 cm in dbh; Or



At least 10 native tree stems per 0.5ha (=20 stems/ha) that are at least 50cm in height, as evidence of potential natural regeneration of native tree species

A. High condition class
A larger patch with good quality native understorey

Patch size > 5 ha
And
> 50% of the perennial understorey vegetation cover is made up of native species



B. High condition class
A patch with high quality native understorey

Patch size > 0.5 ha
And
> 70% of the perennial understorey vegetation cover is made up of native species



C. Moderate condition class
A patch with good quality native understorey


Patch size > 0.5 ha
And
> 50% of the perennial understorey vegetation cover is made up of native species


D. Moderate condition class
A moderate sized patch with connectivity to a native vegetation area; or a mature tree; or a tree with hollows

Patch size > 0.5ha
And
> 30% of the perennial understorey vegetation cover is made up of native species
And





The patch is contiguous with another patch of native vegetation remnant (any native vegetation where cover in each layer present is dominated by native species) >1 ha in area


Or


The patch has at least one tree with hollows or at least one large locally indigenous tree (>60cm dbh).


Dbh is diameter at breast height.
Perennial understorey vegetation cover includes vascular plant species of the ground and shrub layers (where present) with a lifecycle of more than two growing seasons. The ground layer includes herbs (i.e. grasses, graminoids, forbs, and low shrubs [woody plants <0.5m high]). Measurements of perennial understorey vegetation cover exclude annuals, cryptograms, leaf litter or exposed soil.

Contiguous means the patch of the ecological community is continuous with, or in close proximity (within 100 m), to another patch of vegetation that is dominated by native species in each vegetation layer present.




      1. Further information to assist in determining the presence of the ecological community and significant impacts

Land use history will influence the state in which a patch of the ecological community is currently found. The structured form of the ecological community will influence its species richness and diversity. The following information should also be taken into consideration when applying the key diagnostic characteristics and condition thresholds (to assess a site that may include the ecological community and determine the potential impacts on a patch).

Defining a patch

A patch is defined as a discrete and mostly continuous area of the ecological community3. Patches can be spatially variable and often there are one or more areas within a patch that do not meet the key diagnostic characteristics and/or condition thresholds (i.e. localised variation or lower quality areas). Permanent manmade structures, such as roads and buildings, are typically excluded from a patch. However, a patch may include small-scale disturbances, such as tracks or breaks, watercourses or small-scale variations in vegetation that do not significantly alter its overall function (processes such as the movement of wildlife and pollinators, the dispersal of plant propagules, activities of seed and plant predators and many others). Where derived native grassland/shrubland connects discrete patches of the ecological community that are in close proximity (up to 100m apart), this should be considered a single patch of the ecological community rather than individual patches.



Buffer Zone

A buffer zone is a contiguous area adjacent to a patch that is important for protecting the integrity of the ecological community. As the risk of damage to an ecological community is usually greater for actions close to a patch, the purpose of the buffer zone is to minimise this risk by guiding land managers to be aware when the ecological community is nearby and take extra care around the edge of patches. For instance, the buffer zone will help protect the root zone of edge trees and other components of the ecological community from spray drift (fertiliser, pesticide or herbicide sprayed in adjacent land) and other damage.

The buffer zone is not part of the ecological community, so whilst having a buffer zone is strongly recommended, it is not formally protected as a matter of national environmental significance. For EPBC Act approval, changes in use of the land that falls within the buffer zone must not have a significant impact on the ecological community, but there are exemptions for continuing use. If the use of an area that directly adjoins a patch of the ecological community is going to be intensified, approval under EPBC Act may also be required.

The recommended minimum buffer zone is 50 metres from the outer edge of the patch as this distance accounts for the maximum height of the vegetation and likely influences upon the root zone. A larger buffer zone should be applied, where practical, to protect patches that are of very high conservation value or if patches are down slope of drainage lines or a source of eutrophication.



Sampling protocol

On-ground surveys are essential to accurately assess the extent and condition of the ecological community. The recommended sampling protocol involves developing a simple map of the vegetation, landscape qualities and management history (where possible) of the site. The site should then be thoroughly and representatively sampled for vegetation cover and species richness. This should include the areas with the highest level of structural and species richness of native species.

The number of plots required will depend on the size of the patch: the plots should provide a good representation of the species present across the whole patch. The survey plot dimensions may also vary with the patch size, shape and variability but plots of 0.04 ha (quadrats of 20m x 20m) are suggested as likely to be suitable (after Tozer, 2003: Tozer et al., 2010). Search effort should be recorded identifying the number of person hours spent per plot and across the entire patch.

Seasonal variation

Timing of surveys is an important consideration because the ecological community can be variable in its appearance through the year and between years depending on drought-rain cycles. Assessment should occur in spring and summer to early autumn, when the greatest number of species is likely to be detectable and identifiable. Ideally, surveys should be held in more than one season to maximise the chance of detecting all species present. In years of low rainfall, assessment should recognise that many species may not be detected. In these situations it is preferable that surveys are carried out over more than one year. Presence and detectability of some species may also be affected by the time since disturbance such as fire or grazing, so surveys should be planned to occur after an adequate time for some recovery (for example, at least 18 months post fire).


Surrounding environment and national context


The Southern Highlands Shale Forest and Woodland is highly fragmented, sitting within a patchwork of cleared land and native vegetation that connects Morton National Park to Nattai National Park and to the Sydney Catchment Authority Species Areas and the Cumberland Plain. As such, it serves as a corridor facilitating the movement of fauna between these areas.

Actions that may have ‘significant impacts4’ on any patches of Southern Highlands Shale Forest and Woodland meeting the condition thresholds require approval under the EPBC Act. The ecological importance of a patch is also influenced by its surrounding landscape, for example, if connected or nearby to other native vegetation it may contribute substantially to landscape connectivity and function. Similarly, actions beyond the boundary of any patch of Southern Highlands Shale Forest and Woodland may have a significant impact on the patch. For this reason, when considering actions likely to have impacts on this ecological community, it is important to also consider the environment that surrounds any patches that meet the condition thresholds.

Other patches that meet the condition thresholds may occur in isolation and, in addition to requiring protection, may also require management of the surrounding area (e.g. to link them with other native vegetation).

In some cases patches do not currently meet condition thresholds, and so are not considered as part of the nationally protected ecological community (as a Matter of National Environmental Significance). However, in the context of their surroundings, recovery may be possible, so these areas may be considered as a priority for management and funding.



The following indicators of the ecological context provided by the areas surrounding patches of Southern Highlands Shale Forest and Woodland should be considered both when assessing the impacts of actions or proposed actions under the EPBC Act, or when considering priorities for recovery, management and funding.

  • Large size and/or large area to boundary ratio – patches with larger area to boundary ratios are less exposed and more resilient to edge effects (disturbances such as weed invasion and other anthropogenic impacts). However, patches that occur in areas where the ecological community has been most heavily cleared and degraded, or that are at the natural edge of its range may also have importance due to their rarity, genetic significance, connectivity or because of the absence of some threats.

  • Evidence of recruitment of key native plant species or the presence of a range of age cohorts (including through successful assisted regeneration). For example, tree canopy species are present as saplings through to large hollow bearing trees.

  • Good faunal habitat as indicated by diversity of landscape, patches containing mature trees (particularly those with hollows), logs, natural rock outcrops.

  • High native species richness, possibly including many understorey plant species or native fauna species.

  • Presence of nationally or state listed threatened species or patches that contain a unique combination of species and/or rare or important species in the context of the particular ecological community or local region (e.g. a variant of the patch with unique fauna and/or understorey flora composition; or a patch that contains flora or fauna that has largely declined in the ecological community or region).

  • Areas with minimal weeds and feral animals, or where these threats can be managed.

  • Presence of cryptograms, soil crust and leaf litter on the soil surface indicating low disturbance and potential for good functional attributes such as nutrient cycling.

  • Connectivity to other native vegetation remnants or restoration works (e.g. native plantings in particular), a patch in an important position between (or linking) other patches in the landscape. This can contribute to movement of fauna and transfer of pollen and seeds.


Additional information on ecological processes can be found in Appendix B.

Area critical to the survival of the ecological community


Areas that meet the minimum condition thresholds (i.e. moderate condition class) are considered critical to the survival of the ecological community. Additional areas such as adjoining native vegetation and areas that meet the description of the ecological community but not the condition thresholds are also considered important to the survival of the ecological community, for example, buffers for higher condition areas, and should also be considered as part of the surrounding environment, landscape context and other significant considerations.

Geographic extent and patch size distribution


The Southern Highlands Shale Forest and Woodland is endemic to New South Wales, and limited to the Sydney Basin Bioregion. It is known to occur in the Wingecarribee Local Government Area (as defined as at January 2015), but may occur in adjacent areas of the Sydney Basin Bioregion.

The ecological community has been subject to extensive clearing and degradation and now exists in a highly fragmented state. Remnants consist mostly of small isolated pockets some of which may be low quality that do not meet the condition thresholds for the national ecological community.



    1. Other existing protection (relationship to State-listed ecological community)


The ‘Southern Highlands Shale Woodlands’ ecological community was listed under the NSW Threatened Species Conservation Act 1995 as an endangered ecological community in 2001. The nationally listed Southern Highlands Shale Forest and Woodland, includes the state listed ecological community where a patch meets the key diagnostic characteristics and condition thresholds.

Listed threatened species


Table 1: Threatened flora and fauna species associated with Southern Highlands Shale Forest and Woodland.

Scientific name

Common name

TSC

EPBC

Flora

Eucalyptus macarthurii

Paddy’s River box

V

-

Fauna

Amphibians

Heleioporus australiacus

giant burrowing frog

V

V

Reptiles

Varanus rosenbergi

Rosenberg’s goanna, heath goanna

V

-

Birds

Anthochaera phrygia

regent honeyeater

CE

E

Callocephalon fimbriatum

gang gang cockatoo

V

-

Calyptorhynchus lathami

glossy black cockatoo

V

-

Climacteris picumnus victoriae

brown treecreeper (south eastern)

V

-

Daphoenositta chrysoptera

varied sittella

V

-

Melanodryas cucullata cucullata

hooded robin (south eastern)

V

-

Neophema pulchella

turquoise parrot

V

-

Ninox strenua

powerful owl

V

-

Petroica boodang

scarlet robin

V

-

Mammals

Cercartetus nanus

eastern pygmy possum

V

-

Chalinolobus dwyeri

large-eared pied bat

V

V

Dasyurus maculatus maculatus

spotted-tailed quoll (SE mainland popn)

V

E

Falsistrellus tasmaniensis

great pipistrelle

V

-

Miniopterus schreibersii oceanensis

eastern bentwing bat

V

-

Myotis macropus

southern myotis

V

-

Petaurus australis

yellow-bellied glider

V

-

Phascolarctos cinereus

koala (combined populations of Qld, NSW and the ACT)

V

V

Potorous tridactylus tridactylus

long-nosed potoroo (SE mainland)

V

V

Pteropus poliocephalus

grey-headed flying-fox

V

V

Scoteanax rueppellii

greater broad-nosed bat

V

-

V= vulnerable, E= endangered, CE= critically endangered

TSC = NSW Threatened Species Conservation Act 1995

EPBC = C/wth Environment Protection and Biodiversity Conservation Act 1999




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