Brigalow Belt North bioregion

Description Figure 2 Monitoring data coverage Area: 59 824 km2

Land types in the Brigalow Belt North bioregion include undulating to rugged ranges and alluvial plains. Vegetation is primarily acacia open forests and eucalypt woodlands. The main rural land use is beef cattle grazing on pastoral leases; however, coal mining is a major regional economic driver. Around Bowen, irrigation water underpins a thriving horticultural industry. Major population centres are Bowen, bioregion boundary Collinsville and Alpha. RMDC

Location Data sources available The Brigalow Belt North bioregion is located in Data are collected using: central east Queensland (see Figures 1 and 2). n Rapid Mobile Data Collection (RMDC) supported Figure 1 Location of the Brigalow Belt by AussieGRASS simulation (to measure pasture North bioregion growth and utilisation) n remote sensing (using the Multiple Regression Bare Ground Index, version bi1). Reliability in reporting:

n RMDC data have moderate reliability for reporting change in landscape function (visual estimates made along road traverses, data broadly describe landscape function)

n AussieGRASS simulation covers all the rangelands; modelled results are validated with some ground truthing. Other datasets include:

n domestic stocking density, which has moderate reliability for reporting change Location of Brigalow Belt North bioregion n fire extent, intensity and frequency, which has high reliability

Brigalow Belt North bioregion 1 n dust Hills, Townsville Plains and Wyarra Hills. n distance from water Sub-IBRAs that showed some loss were Anakie Inlier, n distribution and relative abundance of invasive Belyando Downs, Bogie River Hills, Cape River Hills, animals and weeds Northern Bowen Basin, South Drummond Basin and Upper Belyando Floodout. n land use n land values. Sustainable management

Climate Critical stock forage

The Brigalow Belt North bioregion has a semiarid to AussieGRASS and levels of simulated pasture tropical climate with predominantly summer rainfall. utilisation and change Spatially averaged median (1890–2005) rainfall is 590 mm (April to March rainfall year; see Figure 3). For the period 1976–1990 compared with 1991–2005, all sub-IBRA regions showed an increase in utilisation. Figure 3 Decile rainfall for the period The largest increases were in Anakie Inlier, where 1991–1992 to 2004–2005 there was a greater than 50% relative (10% absolute) 10 increase between the two periods. The Wyarra Hills, 9 South Drummond Basin, Northern Bowen Basin, 8 7 Townsville Plains and Beucazon Hills sub-IBRA 6 median regions showed a >30% relative (5–8% absolute) 5 4 increase in utilisation since the 1976–1990 period. 3 These are spatially averaged values and excessive Rainfall decile 2 1 utilisation, and the magnitude of increase over time 0 1991-92 1993-94 1995-96 1997-98 1999-00 2001-02 2003-04 is likely to be greater in some areas (paddocks and Rainfall year leases), because half the landscape will be subjected to utilisation levels greater than the sub-IBRA means. Annual rainfall is for the 12‑month period 1 April to 31 March. Plant species richness Decile rainfall was quite variable from one year to the There are no suitable data for reporting change in next, but in summary, it increased and then decreased. plant species richness. Early and later years were very much below average (1991–1992, 1992–1993, 1994–1995, 2002–2003 and Change in woody cover 2004–2005). The year 1998–1999 was exceptionally wet. Statewide Landcover and Trees Study (SLATS) Note that regional averaging of rainfall conceals spatial variability. Some parts of the Brigalow Belt North There was a substantial reduction in woody cover bioregion probably experienced better seasonal quality (largely due to clearing) in the Upper Belyando and others worse during the 1992–2005 period. Floodout sub-IBRA between 1991 and 2003. There were lesser declines in woody cover in the Belyando Downs and South Drummond Basin sub-IBRAs. Landscape function Changes elsewhere (the most northern areas) were relatively minor. There is high reliability for reporting Visually assessed vegetation and soil attribute data change in woody cover based on SLATS. collected along road traverses with the RMDC method

All sub-Interim Biogeographic Regionalisation for Australia (IBRA) areas showed either significant or some loss of function.

Sub-IBRAs that showed significant loss were Beucazon

2 Rangelands 2008 — Taking the Pulse Weeds SLATS woody Change cover 1991 to The following weeds are known to occur in the Sub-IBRA 1991 2003 2003 Brigalow Belt North bioregion: Upper Belyando 49.25% 29.57% –19.68% Floodout Common name Scientific name Belyando Downs 47.95% 38.69% –9.26% Athel pine Tamarix aphylla South Drummond 63.37% 54.56% –8.81% Bellyache bush Jatropha gossypifolia Basin Chinee apple Ziziyphus mauritiana Anakie Inlier 80.25% 74.84% –5.41% Creeping lantana Lantana montevidensis Northern Bowen 60.24% 55.75% –4.48% Giant rats tail grass Sporobolus natalensis Basin and S. pyramidalis Cape River Hills 83.02% 79.87% –3.15% Hymenachne Hymenachne amplexicaulis Townsville Plains 58.33% 56.64% –1.69% Hyptis Hyptis suaveolens Wyarra Hills 84.12% 83.11% –1.02% Lantana Lantana camara Beucazon Hills 72.98% 72.51% –0.47% Mesquite Prosopis spp. Bogie River Hills 73.54% 73.30% –0.24% Mimosa Mimosa pigra IBRA = Interim Biogeographic Regionalisation for Australia; Mother of millions Bryophyllum tubiflorum SLATS = Statewide Landcover and Trees Study and hybrids Parkinsonia Parkinsonia aculeata Distance from stock water Parthenium weed Parthenium hysterophorus Based on the locations of stock waterpoints sourced Prickly acacia Acacia nilotica subsp. from Geoscience Australia’s GEODATA TOPO 250K indica vector product (Series 3, June 2006), the percentage area Rubber vine Cryptostegia grandiflora within three kilometres of permanent and semipermanent See www.anra.gov.au for distribution maps sources of stock water for each sub-IBRA is:

Townsville Plains (BBN1) 17.1% Components of total Bogie River Hills (BBN2) 32.6% grazing pressure Cape River Hills (BBN3) 34.6% Beucazon Hills (BBN4) 65.9% Domestic stocking density Wyarra Hills (BBN5) 40.0% Approximately 90% of the Brigalow Belt North Northern Bowen Basin (BBN6) 30.2% bioregion is grazed. Data from the Australian Bureau Belyando Downs (BBN7) 59.9% of Statistics showed that stocking density decreased Upper Belyando Floodout (BBN8) 89.8% initially then gradually increased (more or less continually) Anakie Inlier (BBN9) 51.4% and again decreased towards the end of the reporting South Drummond Basin (BBN13) 45.7% period. This was a lagged response to persistent BBN = Brigalow Belt North seasonal conditions. The 1992 stocking density was 14% Note: complete sub-IBRA area analysed above the average for the 1983–1991 period. This Note that this analysis does not include the locations density decreased to 91% of the base in 1994 and 1995, of natural waters, which provide additional sources increased to 28% above base in 2001 and then declined of water for stock — particularly following good to 7% above the base in 2003. The 2004 stocking wet-season rains. It is not possible to report change density was 14% above the base (last year of available in watered area for the 1992–2005 period. data). Note that spatial averaging conceals likely variation in stocking density trends across the bioregion.

Kangaroos There is insufficient data coverage to reliably report for the Brigalow Belt North bioregion.

Brigalow Belt North bioregion 3 Invasive animals n 14 threatened bird species (including one extinct species, the paradise parrot) Invasive animal species known to occur in the Brigalow Belt North bioregion include: n 9 threatened reptile species n 1 threatened amphibian species Common name Scientific name Feral pig Sus scrofa n no threatened fish species. Deer Cervidae family More than 20% of the bioregion was cleared Fox Vulpes vulpes (Biodiversity Working Group indicator: Habitat loss), Rabbit Oryctolagus cuniculus and a case study has reported on how clearing affects Wild dog Canis spp. biodiversity (see Case studies: habitat loss and Feral cat Felis cattus fragmentation, Habitat Loss by Clearing section Cane toad Bufo marinus of Biodiversity, Chapter 3). The bioregion also has areas of dense rubber vine (transformer species, See www.anra.gov.au for distribution maps Biodiversity Working Group indicator: Transformers).

Products that support reporting Socioeconomic characteristics of landscape function and sustainable management Land use and value

Fire Approximately 90% of the Brigalow Belt North bioregion is grazed. Approximately 5.4% of the Brigalow Belt North bioregion area was burnt in 1997, while 3.1% was burnt The unimproved rangeland values as at June 2006 were in 2001. Fire was insignificant in other years between the highest of any bioregion in Queensland: $34 873 2 1998 and 2005. Increased fire extent in 1997 and 2001 ± $3302/km on average (value expressed in 2005 may have been initiated by preceding higher rainfall dollars). There was a large range in average unimproved 2 (see Figure 3, above) and suitable conditions for burning. value across sub-IBRAs ($3772 to $64 328/km ). It is not possible to report change in land values. The frequency of fire between 1997 and 2005 was low, with a mean frequency (log transformed) of 0.04. 10 Key management issues Dust and features The mean Dust Storm Index value (1992–2005) was Major issues and features of the Brigalow Belt North low, at 1.53. Dust levels were low in the northeast bioregion are: corner of the bioregion and negligible elsewhere. n high pasture utilisation and potential loss of biodiversity

n increasing degraded areas Biodiversity n Parthenium spread (particularly in high-use and Characteristics of the Brigalow Belt North bioregion degraded areas) include (Biodiversity Working Group indicator: Threatened species; see Section 7 of Chapter 3 of n other weeds of national significance (eg rubbervine) Rangelands 2008 — Taking the Pulse): and woody plant increase, particularly along drainage lines n 29 threatened plant species n woodland thickening in remnant areas n 9 threatened mammal species (includes the western quoll, listed as Vulnerable under the n regrowth of previously cleared woody vegetation Environment Protection and Biodiversity Conservation in non-remnant areas. Act 1999 (EPBC Act), but is extinct from this bioregion).

4 Rangelands 2008 — Taking the Pulse