Soil/Landform Unit 76

Pockets of remnant woodlands generally are found on crests and upper slopes of this landscape.

Area:

6566 ha

0.49% of CMA region

Paleogene and Neogene quartzitic sands outcrop in many areas north and west of the Otway Range. Widespread surface redistribution of this sand has resulted in development of a gentle landscape with sands overlying more clayey material in specified areas. The largest area is east of Kawarren in the catchment of Porcupine Creek, and another extensive area is found in the upper reaches of Tomahawk Creek. Somewhat steeper slopes with a predominance of deep relatively uniform sands occur to the east of Forrest, while the area near Princetown has broader crests and narrower drainage lines. Hardpans are a feature of the soils and the impeded drainage leads to waterlogging on many sites. The native vegetation consists of woodlands of

Eucalyptus nitida

and

E. radiata

, with closed scrubs of shrub species in the drainage lines. Clearing of these areas for agriculture has been attempted in many areas, but impeded drainage on sites with hardpans and excessive drainage on sites without them create management difficulties. Deep ripping of the hardpans may improve site drainage, but low soil

and low fertility also have to be contended with for successful pasture establishment. Most areas remain as wildlife habitats, with the exceptions of one area near Princetown and part of the area near Tomahawk Creek, which border the Heytesbury Soldier Settlement Scheme.

Lower colluvial slopes of gentle long rises

Component	1	2	3	4	5	6
Proportion of soil-landform unit	30%	25%	15%	15%	5%	10%
CLIMATE Rainfall (mm)	Annual: 800-1000, lowest January (40), highest August (120)
Temperature (^oC)	Annual: 13, lowest July (8), highest February (18)
Seasonal growth limitations	Temperature: less than 10^oC (av.) June-August Precipitation: less than potential evapotranspiration late October-March
GEOLOGY Age and lithology	Paleogene unconolidated mudstone, sandstone			Neogene unconsolidated marine marl and fluvial sand, clay and silt
Geomorphology	3.2.2 Dissected upland ranges of the Southern Uplands
LANDUSE	Uncleared areas: Nature conservation; water supply; sand and gravel extraction; hardwod and forestry for posts, poles and fuel Minor cleared areas: Beef cattle grazing; water supply
TOPOGRAPHY Landscape	Undulating plains
Elevation range (m)	60-230
Local relief (m)	45
Drainage pattern	Trellis
Drainage density (km/km²)	2.5
Landform	Rises				Terraces	Drainage lines
Landform element	Crest and slope	Upper slope	Mid slope	Lower slope	-	-
Slope and range (%)	21 (9-38)	9 (2-21)	5 (2-11)	16 (5-33)	2 (0-5)	0 (0-1)
Slope shape	Convex	Convex	Linear	Convex	Linear	Linear
NATIVE VEGETATION Structure	Woodland	Woodland	Open woodland	Woodland	Open forest	Closed scrub
Dominant species	E. radiata, E. nitida	E. raidata, E. nitida	E. radiata, E. nitida	E. radiata, E. nitida, E. ovata	E. ovata, E. viminalis, E. radiata, E. baxteri	Melaleuca squarrosa, Cassuarine littoralis, Aotus ericoides
SOIL Parent material	Woodland	Low woodland	Open woodland	Woodland	Open forest	Closed scrub
Description (Corangamite Soil Group)	Grey sand soils (29)	Grey sand soils with hardpans (29)	Grey sand soils, structured clay underlay (22)	Grey sand soils, structured clay underlay (22)	Grey sand soils, structured clay underlay (22)	Black sand soils (34)
Soil type sites	OTR742	OTR608	OTR737	-	OTR737	OTR609, OTR739
Surface texture	Loamy sand	Loamy sand	Sandy loam	Sandy loam	Sandy loam	Silty loam
Permeability	Very high	Very low	Very low	Low	Very low	High
Depth (m)	>2	0.8	>2	>2	>2	>2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Very low inherent fertility and high permeability lead to nutrient decline. Steeper slopes with compacted soils are prone to sheet, rill and scour gully erosion.	Hardpans restrict drainage, leading to seasonal waterlogging. Very low inherent fertility and leaching of highly acidic permeable surfaces lead to nutrient decline.	Low permeability and seasonal perched watertables lead to waterlogging and soil compaction.	Weakly structured soils of low permeability on steeper slopes are prone to sheet erosion.	Low permeability and seasonal perched watertables lead to waterlogging and soil compaction.	High watertables lead to waterlogging and soil compaction. Runoff from adjacent hills leads to flooding and siltation.

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