The Galilee subregion includes a very high level of ecological spatial variability and turnover (gamma and delta diversity) as a consequence of its large area (248,000 km2) which includes important interactions between the following large-scale environmental factors:
- the large variety of surface geological types and soil types along gradients from the top of the Great Dividing Range towards the Gulf of Carpentaria (to the north), towards the Great Barrier Reef (to the east), towards the Darling River (to the south) and towards Kati Thanga – Lake Eyre (to the south-west) (see sections 1.1.3 and 22.214.171.124.2)
- the rainfall and temperature gradients induced by orographic effects over the Great Dividing Range
- the rainfall and temperature gradients from near-coast (subtropical, higher rainfall, temperature range modulated by oceanic effects) to far inland (arid, low rainfall, more extreme temperature ranges on both seasonal and daily bases) (see Section 126.96.36.199)
- the gradient in seasonality of rainfall across the latitudinal range from 19° South (strongly summer dominated) to 29° South (less predictable and only weakly summer dominated)
- the strong influences of surface water redistribution after rain, even in landscapes with modest degrees of topographic relief, and of access to near-surface groundwater, as is typical of Australian arid and semi-arid landscapes (e.g. Stafford Smith and Morton, 1990)
- the variety of biogeographic influences arising within the eight main river basins that drain to the north, east, south and south-west, and thus each interact with the diverse biota in other surrounding regions and subregions (see Section 1.1.5).
As an indication of the variability within the Galilee subregion, 31 Interim Biogeographic Regional Assessment (IBRA) subregions (Figure 51) and 46 major vegetation subgroups defined in the National Vegetation Information System (NVIS) v4.1 classification (Figure 52, Table 8) are represented. About half of the subregion is dominated by subtropical savannah vegetation communities, where mean annual rainfall is in the range 600 to 800 mm. Mitchell grass (Astrebla) tussock grasslands and Eucalyptus open woodlands with a grassy understorey are the most common NVIS major subgroups in this zone. The remaining half is dominated by semi-arid vegetation communities, where mean annual rainfall is in the range 300 to 600 mm, of which Mulga open woodlands are the most common NVIS major subgroup.
Wetlands and springs listed in A directory of important wetlands in Australia (DIWA; Department of the Environment, 2014c) occupy 0.3% of the area of the subregion and include representation of 21 NVIS v4.1 major vegetation subgroups (Table 8). Nationally mapped riverine floodplains that are also potentially water dependent, at least in part on a seasonal or multi-year basis through flooding and/or elevated watertable, occupy a further 15.5% and include all 46 vegetation subgroups found within the Galilee subregion (Table 8 and Figure 53). For both the DIWA wetlands and the riverine floodplains, the mapped areas include areas of vegetation subgroups that have low likelihood of being dependent on water in excess of local incident rainfall and sourced from subterranean and/or surface water flows (hereafter termed water-dependent as per Methodology for bioregional assessments of the impacts of coal seam gas and coal mining development on water resources ; Barrett et al., 2013)). The inclusion of non-water-dependent ecosystems in DIWA wetlands and riverine floodplains is due to the coarse resolution of existing map polygons which include some areas that are sufficiently distant from water bodies and/or sit well above ecologically accessible groundwater. The remaining 84.2% of the area is of terrestrial vegetation subgroups with limited likelihood of being water-dependent.
Land use includes 21 of the 37 Australian Land Use and Management (ALUM) classification scheme secondary classes, but their occurrence is highly non-uniform (see Figure 10 in Section 1.1.2). Pastoral cattle grazing of native and semi-natural pasture, on both freehold and leasehold lands (Figure 54), is by far the greatest land use (95.4% of the area, approximately two-thirds on leasehold), which is consistent with the predominance of subtropical savannah and semi-arid climates, landscapes and vegetation community types. Conservation is the principal land use for 3.0% of the area, which is below the national average of 8.6% in the Australian National Reserve System (excluding lands of private and Indigenous landholders who have conservation amongst multiple land use objectives) and below the Queensland average of 7.5% (Department of the Environment, 2012).
Source data: IBRA version 7 (2012) ©Commonwealth of Australia 2012 Sub IBRA boundaries produced by ERIN for the National Reserve Systems Section, Australian Government Department of Sustainability, Environment, Water, Population and Communities, Canberra, May 2012
Table 8 National Vegetation Information System (NVIS v4.1) major vegetation subgroups in the Galilee subregion
DIWA is A directory of important wetlands in Australia (Department of the Environment, 2014c)
Source data: (1) NVIS v4.1 major vegetation subgroups, ERIN Vegetation Team, Department of the Environment, Canberra, 2013. (2) A directory of important wetlands in Australia, third edition (Environment Australia, 2001), with additions for wetlands listed after 2001 (last update 23 March 2010). (3) Watercourses and floodplains from the combination of all other datasets listed as sources for Figure 3
Source data: (1) A directory of important wetlands in Australia, third edition (Environment Australia, 2001), with additions for wetlands listed after 2001 (last update 23 March 2010). (2) Collaborative Australian Protected Areas Database (CAPAD, 2010). Australian Department of Sustainability, Environment, Water, Population and Communities. (3) Environmental Resources Information Network (ERIN). Australian Department of Environment. (4) Catchment Scale Land Use Mapping for Australia, Update November 2012 (CLUM Update 11/12). Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES). (5) National Vegetation Information System (NVIS v4.1) major vegetation subgroups. Department of Environment. (6) GEODATA TOPO 250K Series 3 Topographic Data. Geoscience Australia
Table 9 Australian Land Use and Management (ALUM) Classification (version 7) land use classes in the Galilee subregion
Source data: Catchment Scale Land Use Mapping for Australia Update November 2012 (ALUM Update 11/12) dataset. Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES)
Source data: Queensland Digital Cadaster Database (DCDB). Supplied by Queensland Department of Natural Resources and Mines, download date 12/01/2014. Protected Area data are from Queensland Protected Areas Database 5 December 2012. Supplied by the Queensland Department of National Parks, Recreation, Sport and Racing
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- 1.1.1 Bioregion
- 1.1.2 Geography
- 1.1.3 Geology
- 1.1.4 Hydrogeology and groundwater quality
- 1.1.5 Surface water hydrology and water quality
- 1.1.6 Surface water – groundwater interactions
- 1.1.7 Ecology
- Contributors to the Technical Programme
- About this technical product