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Toorongo (To)

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Toorongo- geoArea: 137 sq. km (0.7%).

This land system occurs below the subalpine tract in the western part of the East Victorian Uplands, on high-level plateaux formed on granodiorites and other plutonic rocks.

The topography is hilly to gently undulating and the overall slope of the plateaux are low, possibly reflecting a dissected prior land surface. The dissection pattern is based on jointing in the parent rock and colluvial accumulations and boggy, alluvial floors characteristically occur along the etched-out joint lines. The climate is very humid and this is reflected in the vegetation.
A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Toorongo- image
Rounded hills and steep slopes along incised drainage lines. The control of the drainage pattern by joining is readily apparent.
The humid climate, gentle slopes and parent rock that is easily weathered combine to produce deep, brown or red, well-structured, acidic soils. The dense vegetation cover has tended to produce deep topsoils rich in organic matter.

The subsoil colours are usually bright shades of red, brown or yellowish brown due to the good internal drainage. Young soils, such as those along drainage lines, often contain prominent muscovite mica.

The vegetation is mainly layered open forest III or IV. Closed forest III of Nothofagus cunninghamii occurs within some drainage corridors and open heath grows in swampy areas.

Rainfall, mean (mm)
Temperature, mean (C)
Seasonal growth limitations

Annual 1200 - 1800; lowest January or February (70 - 100), highest August or September (130 - 180)

Annual 8 - 12; lowest July (3 - 7), highest February (16 - 20)
Temperature <10C (av.): April - October
Rainfall < potential evapotranspiration: February; frequent winter snow
Age, lithology

Devonian granodiorites and granites (Toorongo and Baw Baw Grandiorites and Tynong Granites)
Elevation range (m)
Relative relief (m)
Drainage pattern
Drainage density (km/km2)

Undulating to high-level hilly plateaux with approximately concordant crests and joint-based dissection

480 - 1120
120 - 420
PRESENT LAND USEMostly uncleared: hardwood forestry (ash timber); apiculture

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Toorongo- csA study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Toorongo- graph

Percentage of land system
Diagnostic features
Slopes, ridges and low hills based on fine
jointing patterns, and colluvial footslopes
Steep slopes of incised valleys
Treeless flats, often with peat bogs, mainly
along streams
Slope %, typical and (range)
Slope shape
Variable; <25, (5- 60)
Convex, some straight
Variable; >25, (20- 70)
<1, (0- 2)
Parent material
Granodiorite and granite
Locally derived alluvium; plant remains
Black to dark brown sandy clay loam to sandy loam grading into yellowish
brown to reddish brown clay loam to light clay
Mainly black organic sandy loams grading
into grey sandy clay loams, in places with
shallow peaty layers. Some micaceous
undifferentiated greyish brown or yellowish
brown mineral soils of variable texture
Brown and Red Earths/Krasnozems
Gn4.11, Gn4.34, Gn2.21, Um6.12, Uc1.21, Urn 1.44
Mainly Humic Gleys, probably also some
Alluvial Soils
Um5.52, O
Surface texture
Sandy clay loam to sandy loam
Variable; sandy clay loam to sand
Surface consistence
Soft when dry, very friable when moist
Very friable when moist
Depth (m)
Nutrient status
Available soil water capacity
Perviousness to water
Very poor
Exposed stone (%)
Sampled profile number
Structure of vegetation and
characteristic species of
dominant stratum
(+ Predominant species)
Layered open forest III, IV:
E. delegatensis+, with or without E. nitens, at higher elevations grading to E. nitens+ or E. regnans+, with or without E. cypellocarpa, at lower elevations. Nothofagus cunninghamii in understorey mainly in Mount Baw Baw and Mount Toorongo areas
Open forest III:
E. regnans with or without N. cunninghamii
Closed forest II, often ferny:
N. cunninghamii
Open heath:
Baeckea gunniana+, Epacris paludosa+,
Richea continentis+
Bogs with Carex spp.+, Empodisma minus,
Sphagnum sp.+

    Affected process and trend
    Primary resultant deterioration
    Casual activities
    Primary off-site process
    Susceptibility of components
    Incidence with components
    Alteration of vegetation:
    — reduction in leaf area, rooting
    depth and/or perenniality
    Reduced transpiration,
    resulting in increased deep percolation
    Nutrient loss
    Not determined
    Not determined
    Removal of trees
    Increased movement of water to groundwater, increased base-flow of streams
    Increased exposure of surface soil
    Increased overland flow and soil detachment
    Sheet and rill erosion
    1; moderate - high
    2; high
    Clearing, logging,
    burning, road and other
    earth-moving activities,
    trafficking by stock.
    Increased flash flows
    and sediment load.
    Increased physical pressure on soil
    Increased compaction


    Reduced infiltration
    Structure decline

    Sheet and rill erosion
    1; moderate
    2,3; high

    1; moderate - high
    2; high
    Uncommon, but locally severe on log-landing sites

    Increased trafficking by vehicles, export of organic matter

    As for sheet and rill
    erosion above

    Increased spring and decreased summer stream flow
    Increased soil disruption
    Increased soil break-up
    Gully erosion
    1,2; moderate - high
    3; moderate
    As for sheet and rill erosion above
    Increased sediment load
    Comments: Compaction in component 3 can easily destroy the sensitive moss bogs, resulting in channelling, drainage of the bogs and subsequent erosion
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