Soil/Landform Unit 59

Farmland is very uncommon with some pine plantations scattered through this landscape

Area:

9418 ha

0.71% of CMA region

Disconnected remnants of an undulating plain are found on the high parts of the Otway Range from near the Parker River to Gentle Annie Hill. The wettest and most extensive part of this undulating plain comprises soil-landform unit

. All other areas receive an annual rainfall of 1700 mm or less and the tall open forests, although they reach impressive heights, do not approach the 100 m stands reported for within soil-landform unit 60 prior to clearing. Most slopes and crests have moderately deep and fertile soils. The occurrence of extremely deep and friable soils in some areas seems to be related to a change in the nature of the

Cretaceous

beds. The depth to weathering parent material is often in excess of 2 m in these profiles. The remote nature of most of these plateau remnants has hindered their development for agriculture. Many of the areas originally cleared by early settlers have reverted to dense scrub while others have been regenerated to

Eucalyptus regnans

or other hardwood/softwood species. Landslips and loss of soil nutrients in such a wet climate are the main hazards to land use.

E. regnans and E. obliqua of a regrowth stand containing old stags
	Tall open forest on the plateau of the Otway Ranges

Component	1	2	3
Proportion of soil-landform unit	25%	70%	5%
CLIMATE Rainfall (mm)	Annual: 1200-1700, lowest February (65), highest June (170)
Temperature (^oC)	Annual: 10, lowest July (6), highest February (5)
Seasonal growth limitations	Temperature: less than 10^oC (av.) May-October Precipitation: less than potential evapotranspiration early December-February
GEOLOGY Age and lithology	Cretaceous fluvio-volcanic sandstone and conglomerate
Geomorphology	3.1.1 Deeply dissected upland plateau of the Southern Uplands
LANDUSE	Uncleared area: Hardwood forestry for sawlogs and pulpwood; softwood plantations; nature conservation; passive recreation; water supply Minor cleared areas: Some beef cattle grazing on unimproved pastures; most reverting to native forest or converted to pine plantations
TOPOGRAPHY Landscape	Rolling hills along the top of the Otway Range
Elevation range (m)	400-670
Local relief (m)	60
Drainage pattern	Dendritic pattern with some radial areas
Drainage density (km/km²)	2.3
Landform	Hills
Landform element	Upper slope	General slope	Lower slope
Slope and range (%)	15 (1-25)	15 (1-25)	9 (1-12)
Slope shape	Convex	Convex	Concave
NATIVE VEGETATION Structure	Tall open forest	Tall open forest	Tall open forest
Dominant species	E. obliqua, Acacia melanoxylon, E. regnans, E. cypellocarpa	E. obliqua, E. cypellocarpa, E. regnans, Acacia melanoxylong, occasional E. ovata	E. regnans, E. cypellocarpa. E. obliqua, Acacia melanoxylong
SOIL Parent material	In situ deeply weathered sandstine and conglomerate	In situ weathered sandstone and conglomerate	Colluvium
Description (Corangamite Soil Group)	Brown friable gradational soils (7)	Brown friable gradational soils (7)	Brown friable gradational soils (7)
Soil type sites	OTR418, OTR736	OTR414, OTR416, OTR748	OTR428
Surface texture	Loam	Clay loam	Loam
Permeability	High	High	High
Depth (m)	1.8	1.3	>2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	High rainfall and high permeability lead to leaching of nutrients and losses in organic matter and soil structure. Steeper slopes may be subsequently prone to sheet erosion.	High rainfall and moderate permeability lead to leaching of nutrients and losses in organic matter and soil structure. Steeper slopes are subsequently prone to sheet erosion. Clay subsoils on steeper slopes subject to frequent saturation are prone to landslips.	High seasonal watertable leads to waterlogging and soil compaction.

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