McAdam (Mm)

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Mcadam- geo

Area: 9 sq. km (0.1%)

McAdam land system occurs on the hard calcareous Devonian marine sediments which are restricted to a small area near Bindi in the north-west of the survey area. The rock here is the Buchan Caves Limestone, a much harder rock formation than the more mixed calcareous sediments of Bindi land system. The terrain is steep and mountainous with a ridge-and-ravine topography and rock outcrops where slopes cut across bedding planes. The mountains occur at low elevations.

Somewhat shallow clayey soils have formed on the steep slopes from the hard limestones. Soil reaction varies from slightly acidic to alkaline. Good surface drainage, moderate rainfall and low water-holding capacity allied with drainage fractures and solution channels in the bedrock. promote seasonal deficiencies in available water. The native vegetation. probably a grassy woodland I dominated by E. pauciflora with or without E. viminalis, has been almost entirely removed.

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Mcadam- image

Cleared slopes near Bindi

CLIMATE Rainfall, mean (mm) Temperature, mean (°C) Seasonal growth limitations	Annual 500 - 800; lowest July (30 - 50), highest October (50 - 80) Annual 8 - 12; lowest July (3 - 7), highest February (16 - 20) Temperature <10°C (av.): May - September Rainfall < potential evapotranspiration: November – March
GEOLOGY Age, lithology	Devonian limestones, mainly Buchan Caves Limestone (Buchan Group)
PHYSIOGRAPHY Landscape Elevation range (m) Relative relief (m) Drainage pattern Drainage density (km/km²)	Steep mountains with ridge-and-ravine topography 400 - 800 160 - 320 Dendritic 1.0
PRESENT LAND USE	Mostly cleared: grazing of beef cattle and sheep

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Mcadam- cs

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Mcadam- graph

LAND COMPONENT Percentage of land system Diagnostic features	1 65 Long slopes parallel to rock bedding	2 35 Short steep rocky slopes cutting across bedding planes
PHYSIOGRAPHY Slope %, typical and (range) Slope shape	20 - 30. (10 - 50) Straight	30 - 40. (20 - 50) Straight to convex
SOIL
Parent material	Limestone
Description	Dark blocky or crumb structured clay loam to light clay grading into reddish brown or less commonly brown, blocky light or medium clay subsoil. In places very stony or with parent rock floaters; usually shallow. Component 2 has appreciable rock outcrop
Classification	Terra Rossa Soils. Lithosols Uf6.12. Gn4.13
Surface texture	Clay loam to light clay
Surface consistence	Hard when dry, firm when moist
Depth (m)	<0.8
Nutrient status	Moderate
Available soil water capacity	Low
Perviousness to water	Moderate
Drainage	Good
Exposed stone (%)	Variable; 20 - 70
Sampled profile number	-
NATIVE VEGETATION Structure of vegetation and characteristic species of dominant stratum (+ Predominant species)	Grassy woodland I: Upper slopes — E. pauciflora+ Lower slopes — E. pauciflora+, E. viminalis+

Disturbance	Affected process and trend	Primary resultant deterioration			Casual activities	Primary off-site process
Disturbance	Affected process and trend	Form	Susceptibility of components	Incidence with components	Casual activities	Primary off-site process
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	1,2; high	Common	Cultivation, overgrazing, road and dam building and other earth-moving activities, rabbit burrowing, 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; high 2; high (low for Lithosols) 1,2; high Not determined	Common Increased trafficking, overgrazing, export of organic matter	As for sheet and rill erosion above As for sheet and rill erosion above	- Increased flash flows
Increased soil disruption	Increased soil break-up	Gully erosion	I; high	Uncommon	As for sheet and rill erosion above	Increased sediment load.
Comments: Vegetative cover regenerates only slowly particularly on exposed aspects, because of the low water-storage capacity of the soils and the hot, dry summer - autumn season

Page top