Jeeralang (Jg)

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

Area: 316 sq. km (1.6%)

Jeeralang land system occurs on the Cretaceous mudstones, siltstones and sandstones of the South Victorian Uplands.

The terrain is mountainous with pronounced ridge-and ravine topography, long steep slopes and shallow soils. Most occurrences are on the elevated Balook Block or along the Yarragon Monocline. Landslides have been an important slope process, probably because of the soft porous nature of the sediments and the history of tectonic activity. This land is geologically and climatically similar to Gunyah land system but has greater relief and elevation, and longer slopes.

A cool, humid environment, sedimentary rock that weathers relatively easily and steep slopes have resulted in moderately deep, uniform-textured, silty clay loams to clay loams with a medium to fine blocky structure. Roots are common in the subsoil. These soils are thought to be of higher nutrient status than most other soils on sedimentary parent materials in the survey area.

The vegetation is mainly E. regnans layered open forest III with open forest II and III on more exposed aspects or where rainfall is lower.

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

A roadcut through the steep slopes showing the typically shallow soils.

CLIMATE Rainfall, mean (mm) Temperature Seasonal growth limitations, mean (°C)	Annual 900 - 1600; lowest January (60 - 90), highest August or October (120 - 150) Annual 8 - 12; lowest July (3 - 7), highest February (16 - 20) Temperature <10°C (av.): May - September Rainfall < potential evapotranspiration: December - February; occasional winter snow
GEOLOGY Age, lithology	Cretaceous sandstones, mudstones, siltstones and conglomerates of the Strzelecki Group
PHYSIOGRAPHY Landscape Elevation range (m) Relative relief (m) Drainage pattern Drainage density (km/km²)	Steep mountains with ridge-and-ravine topography 140 – 700 100 – 360 0.7
PRESENT LAND USE	Mostly uncleared: hardwood forestry (mainly ash timber); small area in Bulga National Park Minor proportion cleared: grazing of beef and dairy cattle on improved pastures; softwood plantations

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

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

LAND COMPONENT Percentage of land system Diagnostic features	1 85 Steep slopes with old landslide scars common, and narrow rounded crests	2 5 Broader rounded ridge crests mainly at lower elevations	3 5 Steeper slopes of gullies and ravines	4 5 Small flats in the major drainage corridors
PHYSIOGRAPHY Slope %, typical and (range) Slope shape	35-45 (30-60) Straight	5-10 (0-15) Convex	Variable (5-50) Straight	<5 (0-10) Straight
SOIL
Parent material	Mudstone, siltstone and sandstone			Alluvium derived from components 1, 2 and 3
Description	Dark greyish brown to silty clay loam to clay loam merging into brown to yellowish brown silty clay; generally moderately deep and somewhat stony	Similar to component 1, but subsoil heavier and mottled	Similar to component 1	No observations – probably uniformly textured sandy loam to silty loam; some stones and gravel
Classification	Brown Earths Um6.12, Um6.14, Um6.23, Uf6.12, Gn4.31, Gn4.51	Brown Earths Gn3.21, Gn4.31	Brown Earths Um6.12, Um6.14, Um6.23, U6.12, Gn4.31, Gn4.51	Alluvial Soils (See Gunyah land system)
Surface texture	Silty clay to clay loam	Clay loam	Silty clay loam to clay loam	Loam
Surface consistence	Hard	Hard	Hard	Hard
Depth (m)	0.5-1.6	1.0-2.0	0.5-1.6	>2.0
Nutrient status	Moderate	Moderate	Moderate	Moderate
Available soil water capacity	Moderate	Moderate	Moderate	Moderate
Perviousness to water	Moderate to rapid	Moderate to rapid	Moderate to rapid	Moderate to rapid
Drainage	Good	Somewhat poor to good	Good	Good
Exposed stone (%)	0	0	0	0
Sampled profile number	16	38	-	-
NATIVE VEGETATION Structure of vegetation and characteristic species of dominant stratum (+ Predominant species)	Protected aspects, or where rainfall >1100 mm: Layered open forest III: E. regnans More exposed aspects, where rainfall <1100 mm: Open forest II, III: E. obliqua+, E. globulus Imperfectly drained areas with E. ovata		Layered open forest IV with ferns: E. regnans+ with or without E. obliqua, Alsophila australis, Dicksonia antarctica	Shrubby open forest III; 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 - reduction in density of tree roots	Reduced transpiration resulting in: a) increased deep percolation b) increased infiltration and regolith wetness Decreased root-binding	Nutrient loss Landslip and soil creep Soil creep	Not determined 1; high 2,3; low – moderate 1; high 3; moderate	Not determined Common; on cleared land Common; on cleared land	Removal of trees Usually after the removal of trees from steeper land Accelerated by clearing of trees	Increased movement of water to groundwater; increased base-flow of streams Increased sediment load Increased sediment load
Increased exposure of surface soil	Increased overland flow and soil detachment	Sheet and rill erosion	1,3; moderate 2; low	Common	Clearing; logging, burning, road building and other earth-moving activities, trafficking by stock.	Increased flash flows and sediment load.
Increased physical pressure on soil	Increased compaction With Reduced infiltration	Structure decline Sheet and rill erosion	1,2,3; high 4; low-moderate 1,3; moderate 2; low	Uncommon Common	Increased trafficking, export of organic matter As for sheet and rill erosion above	- Increased flash flows
Increased soil disruption	Increased soil break-up	Gully erosion Streambank erosion	1; moderate 4; moderate	Uncommon; local occurrences Uncommon	As for sheet and rill erosion above As for sheet and rill erosion above	Increased sediment load Increased sediment load

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