Regional ecosystem details for 4.9.2
| Regional ecosystem | 4.9.2 |
|---|---|
| Vegetation Management Act class | Least concern |
| Wetlands | Not a Wetland |
| Biodiversity status | No concern at present |
| Subregion | 2, 3, (5.5) |
| Estimated extent1 | Pre-clearing 73000 ha; Remnant 2021 73000 ha |
| Short description | Astrebla lappacea and A. pectinata +/- A. elymoides tussock grassland on Cretaceous sediments |
| Structure code | Tussock Grassland |
| Description | Astrebla lappacea, A. pectinata tussock grassland to open tussock grassland. The ephemeral grasses Enneapogon avenaceus and Iseilema vaginiflorum occur frequently and other species infrequently. A large number of forb species may occur, many of them ephemeral, which are seasonally abundant. Frequent species include Atriplex spongiosa, Ipomoea lonchophylla, Cullen cinereum, Salsola australis and Sida trichopoda. Other forbs occur infrequently. In overgrazed area, ephemeral grasses such Dactyloctenium radulans and Iseilema vaginiflorum and ephemeral forbs such as Amaranthus mitchellii, Harmsiodoxa puberula, Rhodanthe floribunda and Salsola australis, predominate and form seasonal herb lands. Occurs on flat to gently undulating plains formed on fresh Cretaceous sediments. Soils are shallow to moderately deep, brown cracking clays with a soft, self-mulching surface. A weak crust occurs. Traces of ironstone gravel occur of the surface. Soils are moderately to very strongly alkaline with soft lime present and gypsum usually occurs at depth. Not a Wetland. (BVG1M: 30b). Vegetation communities in this regional ecosystem include: 4.9.2a: Aristida latifolia, Enneapogon polyphyllus open grassland wooded with scattered Atalaya hemiglauca and Ventilago viminalis. Gilgai depressions dominated by perennial grasses such as Bothriochloa ewartiana, Eulalia aurea and Astrebla spp. Occurs on flat to gently undulating plains. Associated soils are generally shallow to deep, red clays with moderate to abundant amounts of ironstone and lateritic or siliceous gravel on the surface. Not a Wetland. (BVG1M: 30b). 4.9.2b: Mixed tussock grassland, with combinations of the species Astrebla spp., Aristida latifolia, Enneapogon sp. mixed tussock grassland. Emergent Atalaya hemiglauca, Ventilago viminalis and Corymbia terminalis commonly occur. Occurs on rises of exposed Cretaceous shale and limestone with rocks to the surface. Cracking clay soils. Not a Wetland. (BVG1M: 30b). 4.9.2x1: Enneapogon cylindricus and E. avenaceus open tussock grassland to tussock grassland. Other species include Dactyloctenium radulans, Heliotropium spp. and Salsola australis. Commonly appears as bare limestone in times of drought. Occurs on flat to gently undulating exposures of Tertiary limestone in the south-west of the bioregion. Not a Wetland. (BVG1M: 31b). |
| Supplementary description | Neldner (1991), 42d (84); Turner et al. (1993), F4 (1); Wilson and Purdie (1990a), F2 (45, 48) |
| Protected areas | Diamantina NP |
| Fire management guidelines | INTERVAL: Fire return interval not relevant. INTERVAL_MIN: 100. INTERVAL_MAX: 100. STRATEGY: Do not burn deliberately. The grasses and forbs of Astrebla spp. dominated communities do not require fire for regeneration. Protection relies on management of fire in the surrounding country to prevent running fires entering Astrebla spp. communities, particularly at times of low soil moisture. ISSUES: Fire can sometimes be used as a tool to control woody thickening and woody weeds in grasslands. Moderate intensity fire is required for a successful kill of the woody species but good moisture levels are required to ensure recovery of the ground layer. Large scale germination of woody species is most likely to occur in high rainfall years. The best management opportunity is usually after storms at the end of the subsequent dry season, although exclusion of grazing pressure may still be required to ensure sufficient fuel loads. |
| Comments | 4.9.2: Was previously partly mapped as 4.9.12x1. Floristic composition varies with seasonal conditions and land use. Astrebla pectinata predominates after several dry years, while A. lappacea and Dichanthium spp. increase in wetter years. In overgrazed areas, around watering points, ephemeral grasses such as Dactyloctenium radulans and Iseilema vaginiflorum, and ephemeral forbs predominate. Naturalised species associated with this regional ecosystem include *Portulaca oleracea. 4.9.2x1: Previously mapped as part of 4.9.13d. |
1 Estimated extent is from version 13.1 pre-clearing and 2021 remnant regional ecosystem mapping. Figures are rounded for simplicity. For more precise estimates, including breakdowns by tenure and other themes see remnant vegetation in Queensland.
