Riverina bioregion Description Figure 2 Rangeland Assessment Program monitoring sites in NSW Area: 56 910 km2 The Riverina bioregion is characterised by extensive riverine floodplains with low relief, associated with the SA NSW Murray, Murrumbidgee and Lachlan Rivers. Chenopod shrublands and associated grasslands predominate. Other vegetation types include box woodlands, mallee bioregion boundary woodlands, native grasslands and wetlands. Land tenure RAP monitoring site is mostly freehold. Within the rangelands, sheep and cattle grazing is the most extensive land use. There are also areas of horticulture (wine grapes, vegetables Data RsourcesAP monitoring available sites in NSW and citrus) and grain crops. Major population centres Data sources include: are Hay, Hillston, Loxton and Renmark. n NSW Rangeland Assessment Program (RAP), which provides moderate reliability for reporting Location change, with a moderate number of sites but The Riverina bioregion is located in southern relatively low density for the bioregion, fairly uniform New South Wales (NSW) with a small portion distribution, annual assessments, quantitative data, (3%) in South Australia (SA; see Figures 1 and 2). and a focus on perennial species n SA — no pastoral monitoring data are available Figure 1 Location of the Riverina bioregion n domestic stocking density, which provides moderate reliability n fire extent, intensity and frequency, which provides high reliability n dust n distance from water n distribution and relative abundance of invasive animals and weeds n land use n land values. Location of Riverina bioregion Riverina bioregion 1 Climate Percentage of reassessed Number sites showing: The Riverina bioregion has a semiarid climate with of site- Decline: Increase: low, winter-dominant rainfall, hot summers and cool by-year >4 >4 winters. Spatially averaged median (1890–2005) Seasonal combi- decrease No increase rainfall is 272 mm (April to March rainfall year; see quality nations in index change in index Figure 3). Above average 57 7% 89% 4% Figure 3 Decile rainfall for the period Average 72 6% 86% 8% 1991–1992 to 2004–2005 Below average 54 5% 89% 6% 10 9 8 7 South Australia 6 median 5 There are no suitable data for reporting change. 4 3 Rainfall decile 2 1 0 Sustainable management 1991-92 1993-94 1995-96 1997-98 1999-00 2001-02 2003-04 Rainfall year Critical stock forage Annual rainfall is for the 12‑month period 1 April New South Wales to 31 March. RAP, frequency of the palatable and perennial grass, Decile rainfall was highly variable throughout the (2P) Austodanthonia caespitosa reporting period. The years 1991–1992, 1994–1995, 2001–2002 and 2002–2003 were very dry. Years of When seasonal quality was above average, 13% above-average seasonal quality (based on decile rainfall) of site–time assessments showed a decline in the included 1992–1993, 1993–1994 and 1999–2000. frequency of Austodanthonia caespitosa. No sites assessed following below-average seasonal quality Note that regional averaging of rainfall conceals showed an increase in the frequency of A. caespitosa. spatial variability. Some parts of the Riverina bioregion probably experienced better seasonal quality and Percentage of reassessed others worse during the 1992–2005 period. sites showing: Number Decline: Increase: of site- > 18 > 13 Landscape function by-year decrease increase Seasonal combi- in No in quality nations frequency change frequency New South Wales Above average 68 13% 72% 15% RAP, index based on the frequency and cover Average 102 13% 66% 21% of perennial herbage species Below When seasonal quality was above average, 7% of average 51 22% 78% 0% site–time assessments showed a decline in the index of landscape function. When seasonal quality was Sites selected for reporting change were restricted below average, 6% of site–time assessments showed to those where the 2P grass A. caespitosa was present an increase. at the start of the period. Frequency data from these same sites at subsequent reassessments were then used to report change. 2 Rangelands 2008 — Taking the Pulse South Australia South Australia There are no suitable data for reporting change. Based on the Australian Greenhouse Office definition and mapping of forest extent1, there is a small amount Plant species richness of forest cover in the SA part of the bioregion: 11.82% in 1991 increasing by 0.40% to 12.22% in 2004. New South Wales There is complete coverage of Landsat imagery RAP, count of native perennial and annual for reporting this result. herbage species Distance from stock water Approximately 18% of site–time assessments had The percentage of sub-Interim Biogeographic decreased plant species richness following above- Regionalisation for Australia (IBRA) area within three average seasonal quality and 9% of site–time kilometres of permanent and semipermanent sources assessments had increased plant species richness of stock water is summarised in the following table. The following below-average seasonal quality. locations of stock waterpoints in SA were sourced Percentage of reassessed from state mapping of lease infrastructure, and watered sites showing: area is reported as the percentage of pastoral tenure Number Decline: Increase: within the one sub-IBRA. NSW data were obtained of site- > 11 > 9 from Geoscience Australia’s GEODATA TOPO 250K by-year decrease increase vector product (Series 3, June 2006), and watered area Seasonal combi- in no. No in no. quality nations species change species is the percentage of sub-IBRA area. Note that mapping Above differences between the SA data and the Geoscience average 60 18% 72% 10% Australia product (NSW) mean that the percentage Average 75 8% 73% 19% watered areas reported by each data type are not Below directly comparable. average 45 9% 82% 9% South New South Australia Wales South Australia % sub- % sub- There are no suitable data for reporting change. IBRA % sub- IBRA % sub- within IBRA within IBRA 3 km of area 3 km of area Change in woody cover Sub-IBRA water analysed water analysed Lachlan (RIV1) New South Wales 69.4 100 Statewide Landcover and Trees Study‑type reporting Murrumbidgee (RIV2) 38.6 100 The annualised rate of woody vegetation change Murray Scroll between 2004 and 2006 was 108 ha based on Belt (RIV6) 83.0 18.9 4.6 100 analysis of satellite data using Queensland Statewide IBRA = Interim Biogeographic Regionalisation for Australia; Landcover and Trees Study (SLATS) methods. Woody RIV = Riverina vegetation is defined as woody communities with Note that this analysis does not include the locations 20% crown cover or more (eg woodlands, open of natural waters (eg the rivers), which provide many forests and closed forests) and taller than about two additional sources of water for stock. It is not possible metres. The annualised rate of clearing represents to report change in watered area for the 1992–2005 the annual rate of woody vegetation change, which period for either jurisdiction. is largely due to cropping, pasture and thinning (DNR 2007). At this stage, it is not possible to report change for earlier years of the 1992–2005 period using this method. 1 See http://www.greenhouse.gov.au/ncas/reports/tech09.html Riverina bioregion 3 Weeds Kangaroos Weeds known to occur in the Riverina bioregion include: New South Wales Common name Scientific name The density of kangaroos (on a dry sheep equivalent Alligator weed Alternanthera basis) generally declined across the reporting period, philoxeroides although there were years in which the density Athel pine Tamarix aphylla temporarily increased from the previous year (1996, Blackberry Rubus fruticosus 1999 and 2002). Declines were most pronounced in aggregate the 1992–1993 and 2002–2003 periods. Bridal creeper Asparagus asparagoides The density of kangaroos was greater than the Mesquite Prosopis spp. 1984–1991 average between 1992 and 1999. Privet (broad leaf Ligustrum lucidum Figure 4 shows kangaroo density in the NSW or tree privet) Riverina bioregion. Contributing kangaroo species Privet (small leaf Ligustrum sinense or Chinese privet) are reds, and western and eastern greys. Silver leaf nightshade Solanum elaeagnifolium Figure 4 Kangaroo density in the St John’s wort Hypericum perforatum NSW Riverina bioregion See www.anra.gov.au for distribution maps 180 160 Components of total grazing pressure 140 120 Domestic stocking density 100 Data relating to domestic stocking density are Relative density reported for the whole bioregion. In 1992, 86% of 80 (cf 1984-1991 average) the rangelands component of the Riverina bioregion 60 was grazed. This area reduced to 81% in 2001. Based 199219931994199519961997199819992000200120022003 on data from the Australian Bureau of Statistics and taking account of this reduced area, stocking density It is probable that drier seasonal conditions at declined more-or-less continuously between 1993 various times in the 1992–2003 period contributed and 2003. Stocking density in 1992–1993 was about to the decrease in kangaroo density but there is no 15% above the average for 1983–1991. By 2003, it clear relationship with seasonal quality, as indicated was 74% of this base value and increased slightly in by Figure 3 (showing decile rainfall), above. 2004 (the last year of available data) to be 80% of the 1983–1991 base. The consistent decline was partly Invasive animals attributable to poorer seasonal quality, particularly from 2001 onwards. However, it is also likely that Invasive animal species known to occur in the movement out of less-profitable wool growing into Riverina bioregion include: dryland and irrigated agriculture contributed to the Common name Scientific name decline in stocking density. Note that spatial averaging Feral pig Sus scrofa conceals likely variation in stocking density trends Fox Vulpes vulpes across the bioregion. Rabbit Oryctolagus cuniculus Feral cat Felis cattus Starling Sturnus vulgaris Carp Cyprinus carpio See www.anra.gov.au for distribution maps 4 Rangelands 2008 — Taking the Pulse Products that support reporting Key management issues of landscape function and and features sustainable management Key features and issues of the Riverina bioregion include the following: Fire n NSW: Fire data apply to the whole bioregion.