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Jeeralang (Jg)

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Jeeralang- geoArea: 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 <10C (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- csA 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
Form
Susceptibility of components
Incidence with components
    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 detachmentSheet and rill erosion1,3; moderate
2; low
CommonClearing; 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-upGully 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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