Box Gum Grassy Woodland

Box Gum Grassy Woodland is the name given to the threatened ecological community White Box - Yellow Box - Blakely's Red Gum Grassy Woodland and Derived Native Grasslands. This woodland occurs on fertile soils across our catchment and is characterised by a dominant eucalyptus overstorey (White Box, Yellow Box and Blakely's Red Gum) and a grassy understorey.

Unfortunately large areas of this community have been cleared across our catchment and remaining fragments are listed as critically endangered. The woodland and its waterways provide an essential home to many of our catchments' most threatened species.

Box Gum Grassy Woodland is listed as a threatened ecological community under both the Australian Government's Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and the NSW Threatened Species Conservation Act 1995 (TSC Act). Activities which affect the condition or extent of Box Gum Grassy Woodland may require consent or approval.

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Where does the community occur?

In the Border Rivers-Gwydir catchment, it occurs mainly on the eastern edge of the Plains, on the slopes and on the Tablelands.

Identification

Box Gum Grassy Woodland has a canopy of widely spaced trees dominated by eucalypts (usually Eucalyptus albens, E. melliodora and/or E. blakelyi) with a ground layer  dominated by tussock grasses and a high diversity of herbs. Sparse shrubs may also be present. In the Nandewar bioregion, the community may be dominated by E. moluccana or E. microcarpa.

This community can occur in one of three states:

  1. With an overstorey of trees but no substantial native understorey,
  2. With a native understorey, but no trees, or
  3. With both trees and a substantially native understorey.

For the purposes of the EPBC Act, the presence of a substantially native understorey (with or without trees) is required for a community to be defined as Box Gum Grassy Woodland. Where the understorey does not consist of predominantly native plants, it is considered to be degraded and no longer a viable part of the ecological community.

A patch with predominantly native understorey will have mostly native perennial grasses, with at least 12 non-grass, native species such as lilies, orchids and other wildflowers. At least one understorey species must be an important indicator of condition (e.g. Kangaroo grass). Patches with trees must be greater than 2 ha, but without trees a patch can be greater than 0.1 ha.

Derived Grasslands

Derived grasslands would have originally had a canopy of the dominant Box Gum Grassy Woodland tree species and a species-rich understorey of native grasses, herbs and forbs.  In some cases most or all of the trees have been removed, but the intact grassy understorey still remains. These areas are still valued as habitat.

As a rule of thumb, if you have an area dominated by perennial native grasses with scattered wildflowers, with or without a canopy of the listed trees, it could be Box Gum Grassy Woodland. Seek further advice from the CMA before making significant impacts.

What is not Box Gum Grassy Woodland?

  • Forest or woodland that has a predominantly shrubby understorey (greater than 30%).
  • Forest or woodland with the canopy dominated by different eucalypt species (e.g. E. viminalis).
  • A woodland with native trees, but predominantly exotic species in the understorey.

Threats

Clearing – of both the overstorey and understorey is a major threat to both the extent and the condition of this community. When the woodland understorey is removed, through cultivation for crops or pasture development, the community suffers greatly to the point that it cannot be regenerated.

Grazing – domestic and feral animals can remove many ground cover species.

Weeds – Coolatai grass (Hyparrhenia hirta), African love grass (Eragrostis curvula) and Johnson grass (Sorghum halapense) can enter undisturbed patches and completely replace the ground layer plants. Disturbance through grazing, burning or soil disturbance also favours the introduction of weeds.

Nutrient enrichment – the application of fertiliser can favour the growth of exotic weeds.

Altered fire regimes – species may change composition and eliminate fire-sensitive or fire-dependent species.

Other threats – salinity, mining, housing development, the effects of fragmentation and climate change can threaten the survival of Box Gum Grassy Woodlands. Hotter and drier climatic conditions as a result of global warming are likely to directly affect the flora and fauna of Box Gum Grassy Woodlands as well as altering fire regimes, changing the distribution of weeds and pests and increasing pressure from grazing animals.

Management

Maintain or improve the extent and condition of Box Gum Grassy Woodland communities on your property.

  • It is recommended that you do not clear Box Gum Grassy Woodland patches, even under permissible exemptions from the Native Vegetation Conservation Act.
  • Provide long-term protection for patches through landholder management agreements with the Border Rivers-Gwydir CMA or conservation agreements with the Office of Environment and Heritage or the Nature Conservation Trust.
  • Increase the area of this community through revegetation and assisted natural regeneration.
  • Adopt selective and rotational grazing practices and avoid grazing when ground layer plants are flowering and setting seed (usually spring to midsummer).
  • Do not cultivate in or near patches of this community and avoid opening new tracks, table drains or trenches through stands in good condition.
  • Do not apply fertiliser high in nitrogen and phosphorous to this community, particularly on sites in good condition.
  • Manage weeds in and around existing patches of woodland. Avoid creating soil disturbances that favour weeds. Do not burn sites if Coolatai grass is present.
  • If native tussocks are very large or dense, use mowing or grazing to reduce biomass and create inter-tussock spaces for seed regeneration of other species.
  • Increase species diversity by introducing seedlings of other species from adjacent or similar patches.

Ecosystem function: how healthy woodlands work for you

Healthy Box Gum Grassy Woodlands provides a wide range of benefits that are called 'ecosystem services'. These include traditional services like grazing for livestock, but also other services such as:

  • financial benefits
  • soil formation and cycling
  • nutrient cycling
  • water capture, filtration and delivery to water bodies
  • pollination
  • pest management (e.g. reducing pest pressure on crops)
  • regional climate buffering
  • shade and shelter (e.g. for livestock)
  • breakdown and absorption of wastes
  • a sense of place
  • scenery

Further Information

Rawlings, K., Freudenberger, D. and Carr, D. 2010. A Guide to Managing Box Gum
Grassy Woodlands. Commonwealth of Australia.

Grassy Box Woodlands Conservation Management Network
www.gbwcmn.net.au/home

NSW Threatened Species
www.environment.nsw.gov.au/threatenedspecies/

Australian Government Threatened Species and Ecological Communities
www.environment.gov.au/biodiversity/threatened/index.html

Commonwealth Conservation Advice on White Box – Yellow Box – Blakely's Red Gum
Grassy Woodland and Derived Native Grasslands.
www.environment.gov.au/biodiversity/threatened/communities/pubs/box-gum.pdf

Contact the Border Rivers-Gwydir Catchment Management Authority at
02 6728 8020 or visit our website at http://www.brg.cma.nsw.gov.au


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