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Westbury 1 (W1)

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Westbury1- geoArea: 166 sq. km (0.8%)

Westbury 1 land system occurs on the earlier Pleistocene terrace and on the more distal parts of the Tertiary flood plain deposits. These deposits have been dissected to form low hills and sloping to undulating plains and most of the original land surface has been removed. Westbury 1 differs from Westbury 2 land system in having a drier climate with associated changes in vegetation and from Redgum 1 land system in having greater relief.

The materials of Tertiary and Early Pleistocene deposits were pre-weathered and further weathering has taken place. The soils are deep, leached and almost invariably have yellowish brown duplex profiles. There is some variation in texture and consistence of the topsoil, in the degree of subsurface mottling and in the reaction of the lower subsoil which may range from strongly acid to neutral. The subsoils with neutral reaction are probably highly dispersible and prone to gully erosion.

The remaining native vegetation is mainly an open forest II, often shrubby. Similar vegetation was probably predominant prior to clearing.
A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Westbury1- image
The cleared gentle slopes contrast with the timbered steeper slopes of the Tambo land system.

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

Annual 600 - 900; lowest July or August (30 - 50), highest October (50 - 80)

Annual 12 - 14; lowest July (8 - 10), highest February (19 - 21)
Temperature <10C (av.): June - August
Rainfall < potential evapotranspiration: November – March
GEOLOGY
Age, lithology

Distal parts of
Tertiary floodplain deposits and some 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 undulating plains and low hills

0 - 200
10 - 120
Dendritic
1.0
PRESENT LAND USEMostly cleared: grazing of beef cattle and 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 Westbury1- csA study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Westbury1- graph

LAND COMPONENT
Percentage of land system
Diagnostic features
1
10
Almost flat plateaux remnants
2
80
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, sometimes black, sand to sandy clay loam topsoil grading into greyish
brown or yellowish brown sandy clay loam subsurface soil, sometimes mottled. Abrupt change to
yellowish brown, dark yellowish brown or reddish brown strongly mottled clay subsoil. Subsoil
generally moderately to strongly acidic, sometimes neutral at depth
Limited observations — probably variable; dark
grey deep sand and strongly mottled grey
clay; soil reaction acidic
Classification
Mostly Yellow Podzolic Soils; some Solodic Soils, Soloths; rarely Brown or Red Podzolic Soils
Dy3.21, Dy3.41, Dy3.42, Dy3.31, Dy2.21; rarely Db2.11, Db2.21, Db4.21, Dr5.21
Alluvial Soils, Humic Gleys
Uc1.21, Gn3.91
Surface Texture
Sand to sandy clay loam; mostly sandy 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
Very variable
Drainage
Mostly somewhat poor
Mostly very poor to poor
Exposed stone (%)
Usually 0
0
Sampled profile number
55, 67
49, 51
-
NATIVE VEGETATION
Structure of vegetation and
characteristic species of
dominant stratum
(+ Predominant species)
Open forest II, often shrubby:
Mainly mixed forests, though occasionally pure stands, species including — E. globoidea, E. sieberi (most common predominants), E. tereticornis, E. bosistoana, E. cypellocarpa, E. baxteri (often predominant), E. melliodora and E. sideroxylon
Open forest II, III often shrubby:
E. bridgesiana+ and/or E. globulus+ often occurring in association with E. ovata, E. radiata or E. melliodora

    Disturbance
    Affected process and trend
    Primary resultant deterioration
    Casual activities
    Primary off-site process
    Form
    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; low
    2; moderate
    Not determined
    Cultivating, 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
    3; low – high


    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
    1,3; low
    2; moderate
    Not determined
    As for sheet and rill erosion above
    Increased sediment load and turbidity in streams
    Comments: No observations of deterioration
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