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Soil/Landform Unit 74

Landform Unit Description

Unit 74 image a
Vegetation regeneration on dissected hills after fire north-east of Chapple Vale
      Area: 10 593 ha
      0.79% of CMA region

      Low woodlands of Eucalyptus nitida with understoreys of Leptospermum continentale, L. myrsinoides and Xanthorrhoea australis characterise these hills on the western periphery of the Otway Range. The soils are mainly deep, infertile and excessively drained sands, which contrast sharply with the adjacent gradational profiles of the Lower Cretaceous outcrops. Thus, although rainfall is high, moisture stress and soil infertility severely restrict plant growth. Some attempts have been made to clear tracts of this land and establish pastures for cattle grazing. Trial plots of pine species have also been established. Given sufficient fertiliser and soil ameliorants (such as lime), pastures or even intensive crops could be successfully grown. However, the rates of such chemicals needed to achieve satisfactory production are high and most of the land remains in its natural state. The main activity has been the opening up of numerous soil and gravel extraction pits, most of which have failed to regenerate naturally and now remain as scars on the landscape.
Uni 74 geomorphology

Unit 74 image b
Hills on the margin of the Gellibran River near Devondale
Unit 74 cross section
Unit 74 graphUnit 74 image c
Remnant closed scrube of the valley floor

Component
1
2
3
4
5
Proportion of soil-landform unit
15%
15%
55%
10%
5%
CLIMATE
Rainfall (mm)

Annual: 1000-1350, lowest January (45), highest August (130)
Temperature (oC)
Annual: 12, lowest July (7), highest February (18)
Precipitation less than potential evapotranspiration
Temperature less than 10oC (av.) June-September
Precipitation less than potential evapotranspiration mid November-late March
GEOLOGY
Age and lithology

Paleogene unconsolidated marine glauconitic to carbonaceous sand and mudstone
Geomorphology
LANDUSE
Uncleared areas: Gravel and sand extraction; nature conservation; water supply; active and passive recreation.
TOPOGRAPHY
Landscape

Dissected hills in the western part of the Otway Range
Elevation range (m)
30-270
Local relief (m)
60
Drainage pattern
Dendritic with some radial areas
Drainage density (km/km2)
2.3
Landform
Hills
Valley floors
Landform element
Crest and slope
Broad, slightly depressed area of impeded drainage
Crest and slope
Steep lower slope
-
Slope and range (%)
25 (10-35)
15 (5-20)
20 (5-45)
40 (25-50)
8 (2-12)
Slope shape
Convex
Linear
Convex
Linear
Concave
NATIVE VEGETATION
Structure

Tall shrubland

Closed heath

Low woodland

Woodland

Closed scrub
Dominant species
E. nitida, Acacia suaveolons,
E. baxteri, Leptospermum juniperinum
Cassuarina littoralis, Anthorrhoea australis,
L. continentale, L. myrsinoides,
Melaleuca squarrosa, Aotus ericoides,
Dillwynia glaberrima,
Epacris impressa, Epacris lanuginosa
E. nitida, E. radiata, E. baxteri,
E. viminalis, close to valley floor
E. baxteri, E. radiata, E. nitida
M. squarrosa, L. continentale,
Casuarine littoralis, Gleichenia circinnata,

Bauera rubioides, Sprengelia incarnata
SOIL
Parent material

Quartz sand and gravel

Quartz sand

Quartz sand

Quartz sand

Alluvial sand, plant remains
Description
(Corangamite Soil Group)
White sand soils (29)
Grey sand soils with hardpans (29)
Grey sand soils (29)
Yellow sand soils (29)
Black sand soils (29)
Soil type sites
OTR742
OTR609, OTR739
Surface texture
Coarse sand
Sandy loam
Loamy sand
Loamy sand
Silty loam
Permeability
Very high
Very low
Very high
Very high
Low
Depth (m)
>2
0-1
>2
>2
>2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS
Very low inherent feritlity and high permeability leads to leaching of nutrients. Steeper slopes with compacted soils are prone to sheet, rill and gully (scour) erosion.
Hardpans restrict drainage leading to seasonal waterlogging. Very low inherent fertility with leaching of permeable acidic surface horizons leads to nutrient decline.
Very low inherent fertility and high peremability lead to nutrient decline. Steeper slops with compacted soils are prone to sheet, rill and scour gully erosion.
Steeper slopes with weakly structured soils of low water holding capacity are prone to sheet erosion. Low inherent fertility and high permeability lead to nutrient decline.
High watertables lead to waterlogging and soil compaction. Rapid runoff from adjacent hills leads to flooding and siltation.
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