Westbury 2 (W2)

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Westbury2- geo

Area: 361 sq. km (1.8%)

Westbury 2 is similar to Westbury 1, consisting of gently undulating plains and low hills on the earlier Pleistocene terrace and the more distal parts of the Tertiary flood plains deposits. Dissection is well established with most of the original land surface having been removed. However, quite large remnants of the original surface occur near Westbury. Westbury 2 differs from Westbury 1 in that it occurs in the humid Western lowlands and hence has a more humid climate with associated vegetation differences.

Soils are very similar to those in Westbury 1 and are deep, leached, very acidic and of low fertility. Yellowish brown duplex soils predominate but there is some variation in topsoil texture and consistency, degree of subsurface mottling and the reaction of the lower subsoil, which ranges from strongly acidic to neutral. The subsurface soil tends to become fluid when wet. The subsoils with neutral reaction are probably highly dispersive and susceptible to gully erosion.

The vegetation was probably mainly an open forest II, often shrubby prior to clearing. Only small areas of native vegetation now remain.

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Westbury2- image

Gentle slopes, typical of Westbury 2 land system, south of Traralgon

GEOLOGY Age, lithology	Distal parts of Tertiary floodplain deposits and Lower Pleistocene terrace deposits; gravels, sands, silts and clays
PHYSIOGRAPHY Landscape Elevation range (m) Relative relief (m) Drainage pattern Drainage density (km/km²)	Sloping to gently undulating plains and low hills 20 - 200 10 - 120 Dendritic 1.0
PRESENT LAND USE	Mostly cleared: grazing of beef and dairy cattle and, to a lesser extent sheep on improved pastures; softwood plantations (limited) Minor proportion uncleared: bush grazing of cattle (limited); apiculture

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Westbury2- cs

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Westbury2- graph

LAND COMPONENT Percentage of land system Diagnostic features	1 15 Almost flat plateaux remnants	2 75 Gentle to moderate slopes, rarely steep	3 10 Drainage depressions, in places permanently wet
PHYSIOGRAPHY Slope %, typical and (range) Slope shape	2, (0 - 5) Straight	4 - 8, (0 - 15) Variable	2, (0 - 5) Concave
SOIL
Parent material	Mainly clay, silt and sand, with some intermixed quartz gravel		Locally derived alluvium
Description	Very dark greyish brown sandy loam to sandy clay loam topsoil grading into greyish brown or yellowish brown sandy clay loam subsurface soil, sometimes mottled and fluid when wet. Yellowish brown or dark yellowish brown strongly mottled clay subsoil below. Subsoil usually moderately to strongly acidic, sometimes neutral at depth		Limited observations — probably variable; strongly mottled pale brown to grey medium to heavy textured soils observed
Classification	Mostly Yellow Podzolic Soils and Soloths; some Solodic Soils; rarely Brown Podzolic Soils Dy3.41, Dy3.21, Dy3.42, Dy3.22; rarely Db2.41, Db2.42, Gn4.81		Humic Gleys -
Surface texture	Mostly sandy loam to sandy clay loam		Sand to sandy clay loam
Surface consistence	Friable when moist		Friable when moist
Depth (m)	>2.0		>2.0
Nutrient status	Low		Low
Available soil water capacity	Moderate		Variable
Perviousness to water	Very slow to slow		Probably variable
Drainage	Mostly somewhat poor		Very poor to poor
Exposed stone (%)	Usually 0		0
Sampled profile number	60	50	-
NATIVE VEGETATION Structure of vegetation and characteristic species of dominant stratum (+ Predominant species)	Open forest II: Mainly mixed forests with variable composition, species including — E. dives, E. obliqua, E. radiata, E. bridgesiana (one or more of which predominant) E. cephalocarpa and, in some more poorly drained areas, E. ovata		Open forest II, III, often shrubby: Limited data — probably E. viminalis+ and/or E. ovata+; E. obliqua, E. radiata and E. bridgesiana commonly associated

Disturbance	Affected process and trend	Primary resultant deterioration			Causal activities	Primary off-site process
Disturbance	Affected process and trend	Form	Susceptibility of components	Incidence within components	Causal 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; low 2; moderate	Not determined	Clearing, overgrazing, road and dam building and other earth-moving activities, 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; low 1; low 2; moderate	Not determined Not determined	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; low 3; moderate	Not determined	As for sheet and rill erosion above	Increased sediment load
Comments: No observations of deterioration

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