Regional ecosystem details for 4.9.10
| Regional ecosystem | 4.9.10 |
|---|---|
| Vegetation Management Act class | Least concern |
| Wetlands | Not a Wetland |
| Biodiversity status | No concern at present |
| Subregion | 1, 7, 1.3, (5.1), (2), (1.1), (5.2), (5.3) |
| Estimated extent1 | Pre-clearing 487000 ha; Remnant 2021 487000 ha |
| Short description | Acacia georginae and/or Acacia cambagei tall open shrubland on limestone |
| Structure code | Tall Open Shrubland |
| Description | Acacia georginae and/or A. cambagei tall open shrubland to low open woodland, with scattered Ptilotus obovatus sub shrubs frequently present. The ground stratum is dominated by short-lived perennial grasses, including Aristida latifolia, Enneapogon polyphyllus, Aristida calycina and Enneapogon avenaceus. The long-lived perennial grasses Enteropogon acicularis and Eragrostis xerophila, and the shorter-lived sedge Fimbristylis dichotoma occur frequently. A wide range of forbs may be present. The present Ipomoea muelleri, Pterocaulon serrulatum, Solanum quadriloculatum and Streptoglossa odora occur frequently. Sclerolaena spp., Calotis spp., Hibiscus spp., Portulaca spp., Sida spp., Stenopetalum spp. and other genera occur infrequently but many become seasonally prominent. Occurs on flat to undulating plains derived from Cambrian or Tertiary limestone. Soils shallow to moderately deep, crusted red clays with large amounts of siliceous, and minor ironstone gravel on the surface. Soils are moderately alkaline at depth. Not a Wetland. (BVG1M: 26a). Vegetation communities in this regional ecosystem include: 4.9.10a: Acacia georginae tall open shrubland, occasionally with Corymbia terminalis and Atalaya hemiglauca. A shrub layer may occur, including Acacia georginae, Senna spp., Eremophila spp. and Carissa lanceolata. The ground layer is patchy, most commonly Astrebla pectinata. Bare areas may occur. Occurs on undulating Cambrian limestone surfaces west of the Georgina River. Shallow clay soils. Not a Wetland. (BVG1M: 26a). 4.9.10b: Acacia cambagei and/or A. georginae low open woodland, occasionally with Corymbia terminalis and Atalaya hemiglauca. A shrub layer may occur, including Acacia cambagei, A. georginae, Senna spp., and Eremophila spp. The ground layer is patchy tussock grasses. Occurs on undulating Cambrian limestone surfaces, east (or north) of the Georgina River. Shallow, brown clays with limestone rocks. Not a Wetland. (BVG1M: 26a). 4.9.10c: Acacia georginae tall open shrubland, occasionally with Corymbia terminalis, Atalaya hemiglauca and Grevillea striata. A shrub layer may occur, including Acacia georginae, Senna spp., and Eremophila spp. May include patches of Senna spp., Eremophila spp. Low open shrubland. Occurs on exposures of Tertiary limestone, associated with eroding surfaces around the Georgina River. Shallow brown clays with limestone and chert rocks. Not a Wetland. (BVG1M: 26a). 4.9.10d: Acacia cambagei low open woodland, occasionally with Atalaya hemiglauca and Corymbia terminalis. A shrub layer of Acacia cambagei may occur. The ground layer is patchy tussock grasses. Occurs on exposures of Tertiary limestone. Shallow brown clays with limestone and chert rocks. Not a Wetland. (BVG1M: 26a). |
| Supplementary description | Neldner (1991), 28b (24); Wilson and Purdie (1990a), T2 (44) |
| Fire management guidelines | SEASON: Wet to early dry season when soil is moist. INTENSITY: Low. INTERVAL: Broad interval range of 6-10 years for open acacia with grassy understorey. INTERVAL_MIN: 6. INTERVAL_MAX: 10. STRATEGY: Patchy, within the 20-30% range of area burnt. ISSUES: Acacias (e.g., gidgee) germinate infrequently following high rainfall events, mature slowly and are long-lived. Acacias are vulnerable to frequent and high-severity fires. Fire in surrounding fire-adapted communities can be used to mitigate against wildfire. Fuel loads within Acacia communities can sometimes also require infrequent patchy burns, particularly following years of good rain, to protect them from wildfire and promote diversity at the ground layer. Long absence of fire can result in canopy closure by Acacias and lead to self-protection of these communities. Introduced invasive grasses (e.g., buffel Cenchrus ciliaris) may increase the risk and severity of fires. |
| Comments | 4.9.10: In many places, 80-90% of tall shrubs stand dead with little or no regeneration. Density of short grasses increases after several wet summers. |
1 Estimated extent is from version 13 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.
