Discussion Paper - Part A - Victorian Environmental Assessment ...

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which is essential habitat for some species. Larger trees,however, are favoured for wood products or silviculture,and are therefore less abundant in the forest than otherage classes of trees. One study on the northern plains ofVictoria found that 55 percent of river red gums were10-30 cm in diameter, 35 percent were 31-70 cm indiameter and only 10 percent were greater than 70 cmin diameter (Bennett et al. 1994). It is likely that in pre-European times there was a much greater proportion inthe largest size class.Hollow-formation is one of the most importantecological functions of these older trees. Most river redgums are thought to begin forming hollows atapproximately 120 years of age (Gibbons & Lindenmayer2002) although the age varies, depending on soilfertility, wind exposure and fire history (Harper et al.2005). It takes even longer before the hollows are largeenough to suit the full range of hollow-dependentfauna. A study of hollows on the northern plains foundthat river red gums have fewer hollows than black box,yellow box and grey box (comparing similar-sized trees).Only seven percent of river red gums had hollowsoverall, but 55 percent of the larger trees (with adiameter greater than 70 cm) had hollows (Bennett et al.1994).Hollows are very important for some threatened speciesand many populations are likely to be limited by treehollow availability. Scattered clumps of hollow-bearingtrees and even single hollow-bearing trees in paddockscan support animals (van der Ree et al. 2006). InAustralia, 303 native vertebrate species use tree hollowsfor breeding and shelter—approximately 15 percent ofall terrestrial vertebrate species, or ten percent of reptilespecies, 13 percent of amphibians, 15 percent of birdsand 31 percent of mammals (Gibbons & Lindenmayer2002).The superb parrot is a threatened bird speciescharacteristic of river red gum forests and woodlands.The birds fly from New South Wales to Victoria to breedbetween September and December before returningnorth. At the time of European settlement, the superbparrot was common along the Goulburn River as farupstream as Yea and was frequently recorded nearMelbourne (Figure 5.4). As recently as the 1980s, superbparrots were regularly seen along the lower Ovens River.In Victoria, superb parrots are now found only in anarrow strip between Echuca and Yarrawonga and onlybreed in Barmah State Park and State Forest. The currentVictorian population size is estimated to be 300individuals (Deayton & Deayton 2005).Superb parrots breed in tree hollows and nestingtypically occurs in loose colonies in old healthy (butsometimes dead) river red gum trees with numerousspouts. The trees may be single or clustered but areusually close to water. The birds fly out of the river redgum forests to forage on flowers, fruits and seeds innearby box woodlands. A key measure to protectnesting areas has been the establishment of SpecialProtection Zones (SPZs, see chapter 14) where timberharvesting is excluded from nesting areas in BarmahState Forest, although one of these areas wasinadvertently logged in 2005.Tussock GrasslandNative grasslands are tree-less environments that cansupport a rich diversity of species. Generally, grasslandsare not well-recognised or appreciated and when notflowering it may be difficult to tell the differencebetween nationally significant grasslands and adjacentpaddocks of exotic grasses. Native grasslands have beenextensively destroyed since European settlement and lessthan one percent currently survives—mostly in smallpatches on roadsides, railways, other Crown land andfreehold. Few of these remnants are in good ecologicalcondition (Map 5.1). The Northern Plains GrasslandCommunity is one of the most endangered vegetationcommunities in Victoria and is listed under the Flora andFauna Guarantee Act 1988. Many processes that disturbsoil threaten grasslands including cultivation, clearing,road works and compaction, while other threateningactivities include inappropriate fires, over-grazing,absence of grazing, fertiliser and herbicide application orspray drift and tree-planting. A high proportion ofgrassland species are threatened, including the followingthree examples.Chariot wheels is a small perennial herb (growing toless than 20 cm, see Figure 5.16) restricted to smallareas around Birchip and Mitiamo in Victoria and in thewestern Riverina of New South Wales (see Figure 5.3). Itis vulnerable nationally, in New South Wales andVictoria. The species is characterised by the woollydisc–shaped fruit (5-10 mm), which can be seen inspring and early summer. Ants like to eat the seeds andso the fruits can sometimes be found around theentrances to ants’ nests. Chariot wheels is not found inareas that have been cropped and populations arerestricted to roadsides and isolated remnants. It is furtherthreatened by herbicide use, intensive grazing, treeplantingand soil disturbance.Figure 5.16 Chariot wheels, a small perennial herbfound in grasslands in Victoria.Discussion Paper73
Red swainson-pea is only found in Victoria to the southand west of Echuca in the Victorian Riverina Bioregion(see Figure 5.3). It also occurs in the riverine plains ofNew South Wales. It is endangered in Victoria andvulnerable nationally. It is a prostrate perennial herb withbright red, pea-like flowers in spring (Figure 5.17). Insummer it dies back to a persistent woody rootstockfrom which it resprouts the following autumn. Like othergrassland species, the red swainson-pea is threatened bysoil disturbance, intensive grazing and herbicide use. Asit prefers an open grassland habitat (not too dense withwallaby- and spear-grasses), light sheep grazing maybe beneficial.Figure 5.17 Red swainson-pea, a threatenedperennial herb.Their habitat is confined to cracking clay soils on thefloodplain and is mostly black box with dense but patchyground cover such as lignum. Giles’ planigales may alsouse logs, burrows and grass clumps to shelter fromextreme heat and predators. This species is threatenedby habitat degradation and predation. Lack of floods,firewood collection, ground cover trampling, overgrazingand recreation may contribute to habitat degradation.MalleeVery small parts of the study area between Swan Hilland the South Australian border support malleevegetation. Mallee eucalypt communities support acharacteristic and diverse fauna that includes manyelements restricted to the Murray mallee region. Forexample, the mallee emu-wren inhabits mallee areaswith porcupine grass hummocks. This species isresponsive to the fire history of vegetation andpopulations peak 8-10 years after fire but begin todecline at 30 years after fire (Garnett & Crowley 2000).PROCESSES IMPACTING ONBIODIVERSITYThe grasslands of Terrick Terrick National Park are theVictorian stronghold of the critically endangered plainswanderer—aquail-like grassland specialist (see Figure5.4). Plains-wanderers prefer habitat where there isabout 50 percent bare ground and most plants are lessthan 30 cm tall. They use this vegetation as cover fromaerial predators but can stand on tip-toe to scan forterrestrial predators. Most of the diet of this bird is madeup of insects and seeds from grasses and saltbush.Habitat destruction and modification, includingcultivation, over-grazing, dense pasture growth, weedsand wildfire are the major threats to this species (Baker-Gabb 1995).SaltbushOn the flat alluvial plains of the Murray Scroll Belt,extensive open woodland dominated by saltbushsupports flora and fauna more typical of western NSWand SA. These plains provide the only Victorian habitatfor Giles’ planigale. Other characteristic species includered kangaroo, white-winged fairy-wren, inland dotterel,orange chat and samphire skink.Giles’ planigale is a semi-arid and arid zone speciesthat just extends into the north-west corner of Victoria.The species was only discovered in Victoria in 1985when individuals were found at Lindsay Island, WallpollaIsland and near Neds Corner (west of Mildura).The management and amelioration of key or potentiallythreatening processes is vital to conserving biodiversity.Many potentially threatening processes are listed underthe Flora and Fauna Guarantee Act 1988 and theCommonwealth Environment Protection and BiodiversityConservation Act 1999 (Appendix 8) which require plansfor the amelioration of these threats. An example of apotentially threatening process listed under the Flora andFauna Guarantee Act 1988 is ‘Prevention of passage ofaquatic biota as a result of the presence of instreamstructures’. Management agencies have sought toreduce the impact of instream structures by installingfish ladders or fish ways (Figure 5.18) to help fish movearound dam walls. The major threatening processes inthe study area are discussed below under nine broadheadings.Figure 5.18 Fish ladder at Torrumbarry on theRiver Murray.Clearing and Habitat FragmentationHabitat clearing is one of the major causes of biodiversitydecline in Victoria (DNRE 1997b). Clearing reduces thearea of habitat in which indigenous flora and fauna canlive. For example, large losses of grassland habitatthrough cropping, ploughing, fertiliser and herbicide useand high levels of grazing have reduced many grassland-74 River Red Gum Forests Investigation 2006
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2 GeologyGeology underpins the dive
Page 5 and 6:
Figure 2.2 Schematic diagram of fol
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et al. 2000). This Selwyn Block is
Page 12 and 13:
Figure 2.4 Murray Basin during the
Page 14 and 15:
quartz sand and gravel beds, carbon
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Box 3.1 River MeandersRivers rarely
Page 19 and 20: lakes by flooding from Chalka Creek
Page 21 and 22: major valleys. The large, older fan
Page 23: ecommending representative areas fo
Page 26 and 27: Box 3.2 Barmah Area GeomorphologyTh
Page 28: 4 Climate andHydrological SystemsAu
Page 31 and 32: Figure 4.1 Annual anomalies (based
Page 33: such as messmate have a thick prote
Page 36: Natural Hydrology of the River Murr
Page 39: Table 4.3 Stream flow in major Vict
Page 42 and 43: GroundwaterHydrology also relates t
Page 44 and 45: FloodplainsThe floodplains of the R
Page 46 and 47: 5 BiodiversityBiodiversity is impor
Page 48 and 49: Ecosystem Assessment 2005). Species
Page 51: Figure 5.2 Hairy darling-pea on a r
Page 57 and 58: Figure 5.5 A common blue-tongued li
Page 59: Threatened VertebratesBased on cons
Page 64 and 65: Figure 5.8 Mature river red gum on
Page 66 and 67: Figure 5.12 Tangled lignum at Mulcr
Page 68 and 69: Egrets generally only breed in livi
Page 72 and 73: dependent species including darling
Page 74: Table 5.7 Summary of risk levels to
Page 77 and 78: Figure 5.22 Koala in a river red gu
Page 79 and 80: Examples include the larvae of leaf
Page 81 and 82: Figure 5.27 Cattle on the bank of t
Page 83 and 84: Table 5.8 Comments on fire from exp
Page 85 and 86: 6 Indigenous LandAssociationsThis c
Page 89 and 90: Table 6.1 Summary of area in Victor
Page 91 and 92: waters. The Joint Body is funded to
Page 93 and 94: Consultative ManagementConsultative
Page 95 and 96: 7 Non-IndigenousHistoryThe resource
Page 97 and 98: Figure 7.2 Murray Downs homestead (
Page 99 and 100: Reception Centre established in 194
Page 101 and 102: and rural water supply became the r
Page 103: FisheriesThe collapse of the Murray
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