Soil/Landform Unit 63

Landform Unit Description

Unit 63 image a
On cleared areas, weeds such as blackberries and ragwort become a problem
      Area: 14 257 ha
      1.07% of CMA region

      From Upper Gellibrand to Peters Hill, steep spurs and ridges with long straight slopes and narrow valleys form the rugged northern margin of the Otway Range. The climate is significantly drier than in other parts of the range, with most areas receiving an annual rainfall of about 900 mm. The separation of these drier spurs and ridges from the rest of the range is well reflected by changes in the structure and composition of the native vegetation. In particular, Eucalyptus radiata becomes a prominent member the dominant stratum and the understorey changes from mesophytic species to drier sclerophyllous species such as Acacia mucronata, A. verticillata, Cassini longifolia and Epacris impressa. Most of this unit remains forested and is selectively logged for millable timber. Some parts of the eastern areas have been cleared for grazing, but management is difficult due to the rugged terrain. Softwood plantations have also been established. Landslips and sheet erosion have been severe in some areas, and rapid runoff from these hills creates problems of gully erosion on the plains of the Barwon River.
Unit 63 geomorphology

Unit 63 image b
Deeply dissected hills with rounded crests		Unit 63 cross section
Unit 63 graph
Unit 63 image c
Pine plantation along the plateau of deeply dissected hills

Component
1
2
3
4
5
Proportion of soil-landform unit
10%
50%
4%
35%
1%
CLIMATE
Rainfall (mm)

Annual: 900-1100, lowest January (45), highest August (130)
Temperature (oC)
Annual: 12, lowest July (7), highest February (17)
Seasonal growth limitations
Precipitation: less than potential evapotranspiration mid Nomver - mid March
GEOLOGY
Age and lithology

Cretaceous fluvio-volcanic sandstone and conglomerate
Geomorphology
LANDUSE
Uncleared areas: Hardwood forestry for sawlogs, posts and poles; softwood forestry; nature conservation; active and passive recreation; water supply
Minor cleared areas: Beef cattle grazing on mainly unimproved pastures
TOPOGRAPHY
Landscape

Deeply dissected hills of the Otway Range
Elevation range (m)
150-400
Local relief (m)
150
Drainage pattern
Dendritic
Drainage density (km/km2)
2.7
Landform
Hills
Landform element
Steep slope
North and west facing slopes
Crest and upper slope
South and east facing slopes
Lower slope and drainage lines
Slope and range (%)
60 (20-70)
45 (25-65)
20 (5-3)
45 (25-65)
20 (1-35)
Slope shape
Linear
Linear
Convex
Linear
Concave
NATIVE VEGETATION
Structure

Woodland

Open forest

Open forest

Tall open forest

Tall open forest
Dominant species
E. radiata, E. cypellocarpa
E. obliqua, E. radiata, E. cypellocarpa
E. obliqua, E. radiata, E. cypellocarpa
E. cypellocarpa, E. obliqua
E. cypellocarpa, E. obliqua,
E. ovata, Acacia melanoxylong
SOIL
Parent material

Colluvium

In situ weathered sandstone on conglomerate

In situ weathered sandstone on conglomerate

In situ weathered sandstone on conglomerate

Alluvium colluvium
Description
(Corangamite Soil Group)
Stony brown gradational soils (7)
Brown texture contrast soils (6)
Brown texture contrast soils (6)
Brown gradational soils (7)
Brown gradational soils, weak structure (7)
Soil type sites
OTR732
Surface texture
Fine sandy loam
Loam
Loam
Loam
Silty loam
Permeability
Very high
Moderate
Moderate
High
High
Depth (m)
0.5
0.9
0.9
0.9
>2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS
Stony shallow soils with weak structure and low waterholding capacity on steep slopes are prone to sheet erosion and landslips.
Dry aspect, steep slopes and weakly structured surfaces lead to sheet erosion. Clay subsoils on steep slopes subject to periodic saturation are prone to landslips.
Steeper slopes are prone to sheet erosion.
Steep slopes are prone to sheet erosion. Clay subsoils on steep slopes subject to periodic saturation are prone to landslips.
Weakly structured soils receiving runoff are prone to scour gullying siltation and flooding.
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This page contains material sourced from the Victorian Resources Online (VRO) website, originally published by the State Government of Victoria. The content is licensed under the Creative Commons Attribution 3.0 Australia licence . The material has been adapted and re-formatted; no endorsement by the Victorian Government is implied.