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

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Figure 5.12 Tangled lignum at Mulcra Island andclose-up of flowers.Figure 5.10 River red gum trees dying and in poorcondition on Lindsay Island due to lack of water.Table 5.6 The influence of flood regimes on rushlands, moira grass plains, river red gum forests andbox forests and woodlands in Barmah-Millewa Forest.Main Vegetation TypeFlood Regime 1RushlandsMoira grassplainsRiver red gum forest> 30m 21-30m < 21mBlack boxforest 2Ideal timeJuly–JanuarySeptember–JanuaryAugust–Decemberoccasionalshort floodFrequencynatural averageevery yearevery year9 yearsout of 107 yearsout of 104.5 yearsout of 101 yearout of 10minimum required7.5 yearsout of 10every year7 yearsout of 105 yearsout of 103 yearsout of 10none requiredcurrent8 yearsout of 107 yearsout of 106 yearsout of 104.5 yearsout of 102.5 yearsout of 101 yearout of 10Durationnatural average10 months8 months5 months3 months1.2 months1 monthminimum required2 months5 months 1 month 1 month 0.5 monthnonerequiredcurrent average 5 months 3 months 2 months 1.5 months 0.7 month 0.5 monthSources: MDBC (1992; 2000), Ward (1991).Notes:1. The base parameter is that 80 percent of the forest is flooded for at least one month.2. Includes Black Box Woodland and Open Woodland, which is usually briefly inundated in less than 30 percent of years. YellowBox, Grey Box, Murray Cypress Pine Woodland and Open Woodland are seldom, if ever, flooded.<strong>Discussion</strong> <strong>Paper</strong>69
Many other species of the floodplains are speciallyadapted to the ecological conditions and water regimes.Two well-known floodplain plants are lignum and moiragrass. Three species of lignum occur in the study area—tangled (see figure 5.1 and Figure 5.12), spiny andtwiggy, although spiny lignum is rare in Victoria. Theyare typically green shrubs up to 12 m tall with entangledbranches, but their form is highly dependent on floodingregimes. They mostly occur along rivers, streams andfloodplains, often in association with black box. Whenflooded, lignum provides important nesting habitat forwater birds. It is salt and drought-tolerant but will notsurvive permanent flooding (Roberts & Marston 2000).Figure 5.13 Moira grass in Barmah forest whileflooded and close-up view.Moira grass (sometimes called spiny mud-grass, seeFigure 5.1 and Figure 5.13) is an aquatic to semi-aquaticgrass with pyramid-shaped flower heads up to 15 cmlong. It forms a turf in dry conditions but can grow upto 1.5 m and form floating mats on open water duringflooding (see Table 5.6 for flooding frequency andduration). Moira grass only grows after flooding. Growthrates of 10 mm per day in winter and 20 mm per day inlate spring have been documented in Barmah forest(Ward 1991).Changed water regimes are changing the distribution ofMoira grass. In the past, the extended floods killed redgum seedlings but the absence of extended andfrequent floods is now causing Moira grass plains to beinvaded by river red gum thickets (Bren 2005).Unseasonal summer flooding increases the survival ratesof seedlings, which would otherwise die from summerdroughts. Reduced spring flooding means seedlings arenot inundated for as long or as deep as previously (Bren2005). Giant rush is also encroaching onto Moira grassareas. Moira grass plains have been reduced from about4050 ha (13.5 percent) of Barmah Forest in 1930 toabout 1650 ha (5.5 percent) in 1980 (Chesterfield1986). In Barmah forest, a minimum flood duration of5 months, receding before summer, is required for Moiragrass to out-compete river red gum seedlings and milfoil(Ward 1991). Floods need to be approximately 0.5 m tocompletely submerge river red gum seedlings andprevent premature nodal rooting of Moira grass into thesoil. This equates to a flow of approximately 1500 MLper day in the Gulf Creek (Ward 1991). Moira grass isa preferred species for cattle grazing and Roberts andMarston (2000) suggest that the distribution of Moiragrass on the floodplain may be explained in part by pastcattle stocking rates and practices.Significant animal species of the floodplainsAt a statewide level, riverine forests provide habitat fora wide diversity of vertebrate animals. The forests areimportant for the conservation of woodland birds, includingmany of those in the Woodland Bird Community listedas threatened under the Flora and Fauna Guarantee Act1988 (see Table 5.2). The mature riverine trees containhollows which many mammals and birds need forshelter or breeding, including the threatened squirrelglider, superb parrot and regent parrot. These parrots,in particular, are unlikely to survive in Victoria withoutriverine forests. Fallen woody debris provides shelterfor small mammals, ground foraging birds and manyreptiles. During winter, many birds, such as the flamerobin and pied currawong, migrate from the mountainforests to find food in the river red gum forests.Species usually found in higher rainfall areas such asthe feathertail glider, sugar glider, koala and striatedthornbill (see Figure 5.1) extend their distribution northwestalong the mesic corridor provided by the river redgum forests of the Murray River floodplain. De Vis’banded snake, yellow rosella and barking marsh frogare entirely dependent on river red gum forest habitatin Victoria and the ecosystem provides a stronghold formany other species.Numerous swamps and lakes in the Kerang and SwanHill districts provide breeding, feeding and droughtrefuges for some 60 species of waterbird, including15 waterfowl and 23 species of migratory shorebird.Flooding regimes are particularly important for thesurvival of egrets. Egrets generally breed in floodedforests but feed away from the nesting sites in moreopen wetlands. Egrets take longer than other waterbirds to commence breeding after flooding, and do notbreed successfully unless their nesting sites are floodedfor three to five months. This is thought to preventterrestrial predators from accessing the nests.70 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
Page 10 and 11:
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
Page 17 and 18: 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 68 and 69: Egrets generally only breed in livi
Page 70 and 71: which is essential habitat for some
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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