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Westbury 2 (W2)

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Westbury2- geoArea: 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 USEMostly 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- csA 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
Form
Susceptibility of
components
Incidence within
components
Alteration of vegetation:
— reduction in leaf area, rooting
depth and/or perenniality
Reduced transpiration,
resulting in increased deep percolation
Nutrient lossNot determinedNot determinedRemoval of treesIncreased movement of water to groundwater; increased base-flow of streams
Increased exposure of surface soilIncreased overland flow and soil detachmentSheet and rill erosion1; low
2; moderate
Not determinedClearing, 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 soilIncreased 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 disruptionIncreased soil break-upGully erosion1,2; low
3; moderate
Not determinedAs for sheet and rill erosion aboveIncreased sediment load
Comments: No observations of deterioration
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