Toorongo (To)

	Area: 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.	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.

CLIMATE 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 <10°C (av.): April - October Rainfall < potential evapotranspiration: February; frequent winter snow
GEOLOGY Age, lithology	Devonian granodiorites and granites (Toorongo and Baw Baw Grandiorites and Tynong Granites)
PHYSIOGRAPHY Landscape 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 Rectangular 1.6
PRESENT LAND USE	Mostly uncleared: hardwood forestry (ash timber); apiculture

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

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

LAND COMPONENT Percentage of land system Diagnostic features	1 65 Slopes, ridges and low hills based on fine jointing patterns, and colluvial footslopes	2 20 Steep slopes of incised valleys	3 15 Treeless flats, often with peat bogs, mainly along streams
PHYSIOGRAPHY Slope %, typical and (range) Slope shape	Variable; <25, (5- 60) Convex, some straight	Variable; >25, (20- 70) Concave	<1, (0- 2) Straight
SOIL
Parent material	Granodiorite and granite		Locally derived alluvium; plant remains
Description	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
Classification	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)	>2.0		>2.0
Nutrient status	Moderate		Moderate
Available soil water capacity	Moderate		Moderate
Perviousness to water	Rapid		Rapid
Drainage	Good		Very poor
Exposed stone (%)	<5		0
Sampled profile number	-		-
NATIVE VEGETATION 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.+

Disturbance	Affected process and trend	Primary resultant deterioration			Casual activities	Primary off-site process
Disturbance	Affected process and trend	Form	Susceptibility of components	Incidence with components	Casual activities	Primary off-site process
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	Uncommon	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 With 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 Uncommon	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	Uncommon	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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