Tambo (Tb)

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Tambo- geo

Area: 400 sq. km (2.0%)

Low hills and undulating terrain occur on Ordovician sediments at low elevations close to the southern margin of the East Victorian Uplands and along some of the major river valleys. These areas are mapped as the Tambo land system. Some ridge crests are rounded but most slopes are short and moderately steep. Occurring in scattered localities, this land system is ecologically diverse. The area is topographically similar to the Avon land system on Carboniferous sediments.

Shallow soils, with rock fragments common, particularly in the lower horizons, have formed on the moderate and gentle slopes. Soil depth appears to be limited by rock strata that is resistant to weathering. The soils typically show increasing clay content with depth, the increase appearing to be more gradual than abrupt. The reaction is moderately to strongly acidic, often tending to neutrality at depth.

Open forest II predominates, with open forest III on some protected slopes.

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Tambo- image

The low relief on the rounded hill is apparent when compared with the ridge (right background) of Talbotville land system.

CLIMATE Rainfall, mean (mm) Temperature, mean (°C) Seasonal growth limitations	Annual 700 - 1200; lowest January or February (40 - 80), highest October (100 - 150) Annual 12 - 14; lowest July (8 - 10), highest February (19 - 21) Temperature <10°C (av.): May - September Rainfall < potential evapotranspiration: November – March
GEOLOGY Age, lithology	Mostly Ordovician sandstones, mudstones and shales
PHYSIOGRAPHY Landscape Elevation range (m) Relative relief (m) Drainage pattern Drainage density (km/km²)	Rounded low hills and undulating terrain 40 - 540 40 - 160 Dendritic 0.5
PRESENT LAND USE	Mostly uncleared: hardwood forestry (low productivity except for second grade timber on sheltered slopes); apiculture; bush grazing of cattle (limited); small area in Fairy Dell Scenic Reserve Cleared areas: grazing of cattle on improved pastures

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

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

LAND COMPONENT Percentage of land system Diagnostic features	1 45 Steeper slopes and sharp or sub-rounded peaks	2 30 Gentle lower slopes	3 5 Broad rounded crests	4 10 Protected slopes	5 5 Minor drainage depressions	6 5 Terraces in major drainage corridors
PHYSIOGRAPHY Slope %, typical and (range) Slope shape	20 - 30, (10 - 40) Straight	10 - 15, (5 - 20) Concave	5, (0 - 10) Convex	20 - 30, (10 - 40) Concave	<2, (0 - 5) Concave	<5, (0 - 10) Straight but uneven
SOIL
Parent material	Sandstone, mudstone and shale				Colluvium and local alluvium	Alluvium
Description	Very dark greyish brown loamy sand to loam topsoil; gradual or abrupt change to yellowish brown or reddish brown, sometimes mottled, clay subsoil, usually with blocky structure. Commonly stony, sometimes shallow, probably depending on hardness of underlying rock and slope				Variable; sand to clayey texture; greyish brown, often mottled; may be stony	Limited observation — undifferentiated brown sand
Classification	Yellow Podzolic Soils; some Red Podzolic Soils and Brown Earths; rarely Lithosols Gn3.21, Gn3.54, Gn2.41, Gn2.44, Gn3.11 Dy3.21, Dy3.41				Humic Gleys, Siliceous Sands Gn3.91, Uc1.23	Alluvial Soils Uc1.23
Surface texture	Loamy sand to loam				Variable	-
Surface consistence	Variable; soft to hard when dry				Variable	-
Depth (m)	0.9 - 1.5; <0.9 where hard bedrock and/or steeper slopes				>2.0	>2.0
Nutrient status	Low to moderate				Low to moderate	Low to moderate
Available soil water capacity	Moderate				Very variable	Very variable
Perviousness to water	Mostly slow				Very variable	Very variable
Drainage	Good	Moderately good to good	Somewhat poor to good	Good	Mostly poor	Mostly good
Exposed stone (%)	Generally 0, but up to 20 where soil shallow				0	0
Sampled profile number	-				-	-
NATIVE VEGETATION Structure of vegetation and characteristic species of dominant stratum (+ Predominant species)	Open forest II:		Shrubby open forest I and II:	Open forest II, III often shrubby:	Mostly open forest II: E. ovata+, E. bridgesiana or E. polyanthemos, some times with E. radiata Rarely closed forest II: Acmena smithii, Pittosporum undulatum, climbers, ferns and epiphytes	Limited data — open forest II: E. viminalis+
	E. globoidea usually predominant, occasionally E. polyanthemos or E. consideniana (in poorer drained sites); E. cypellocarpa or E. sideroxylon sometimes associated			E. cypellocarpa+ and/or E. obliqua+; E. radiata or E. globoidea often associated		Limited data — open forest II: E. viminalis+

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	1,2,3; moderate 4; low	Common: on cleared land. Local occurrences in forests	Clearing, logging, burning, overgrazing, road and dam building and other earth-moving activities, rabbit burrowing, trafficking by stock and vehicles.	Increased flash flows and sediment load.
Increased physical pressure on soil	Increased compaction With Reduced infiltration	Structure decline Sheet and rill erosion	1,2,3,4; low 5,6; low – moderate 1,2,3; moderate 4; low	Uncommon Uncommon	Increased trafficking cultivation, overgrazing, export of organic matter As for sheet and rill erosion above	- Increased flash flows
Increased soil disruption	Increased soil break-up	Gully erosion	1,2,3; low - moderate 5; moderate 4,6; low	Uncommon: local occurrence	As for sheet and rill erosion above	Increased sediment load
Comments: -

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