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Moroka (Ma)

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Moroka- geoArea: 25 sq. km (0.1%)

This land system occurs on drainage depressions on plateaux mainly at lower elevations in the subalpine tract. Only the larger drainage depressions are mapped out; most of the remainder are included in Bennison land system. Moroka land system usually has abundant seepage emanating from gentle slopes and almost permanent water in anastomosing channel systems. Past erosional phases are represented in places by relict benches, with structural control evident from massive rock outcrop. Most areas of Moroka land system occur on Carboniferous sediments.

The soils reflect major variation in drainage status. Less than half the area is moderately well drained and has yellow friable soils, with some reddish equivalents apparently related to underlying red-bed shales. In the rest of the area the swamps and seepage zones have shallow organic topsoils or peaty horizons overlying mineral substrata which are usually grey and mottled. All soils are moderately to strongly acidic. The flat to gentle slopes and the high organic matter contents in the surface reduce susceptibility to sheet erosion. Disturbances in drainage lines and destruction of vegetation on higher slopes can cause gullying of stream channels.

Shrubby woodland I or II dominates on the better drained land with closed forest I, open heath or sedgeland where drainage is poorer.
A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Moroka- image
A swampy alluvial plain in the subalpine tract, edged with Eucalyptus stellulata (black sauce) and E. pauciflora (white sallee). The soil at this site contained peat to a depth of 50 cm.

CLIMATE
Rainfall, mean (mm)
Temperature, mean (C)
Seasonal growth limitations

Annual 900 - 1600; lowest January or February (50 - 90), highest August or September (120 - 180)

Annual 8 - 12; lowest July (3 - 7), highest February (16 - 20)
Temperature <10C (av.): April - October
Rainfall < potential evapotranspiration: February; frequent winter snow
GEOLOGY
Age, lithology

Mainly
Carboniferous sandstones, siltstones and shales; Holocene alluvium and colluvium; some rhyodacites, granites and granodiorites
PHYSIOGRAPHY
Landscape
Elevation range (m)
Relative relief (m)
Drainage pattern
Drainage density (km/km2)

Shallow valley floors in the uplands with seepage, braided channels and relict terraces

640 - 1325
5 - 40
Braided
2.5
PRESENT LAND USEMostly uncleared: bush grazing of cattle; apiculture (limited)

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

LAND COMPONENT
Percentage of land system
Diagnostic features
1
45
Gently sloping valley margins,
extensive seepage zones
2
35
Swampy plains with free water
and peat
3
10
Slightly elevated relict benches
4
10
Swampy plains with channel
systems; occasional better
drained terraces
PHYSIOGRAPHY
Slope %, typical and (range)
Slope shape
3 - 5, (2 - 10)
Concave
3, (0 - 6)
Straight
2, (0 - 5)
Straight
<1, (0 - 2)
Concave but uneven
SOIL
Parent material
Sandstone, siltstone and shale; minor, rhyolite and rhyodacite; colluvium and alluvium
Description
Black loam to clay loam topsoil,
often organic, grading into
yellowish brown or grey (in
seepage zones) clay subsoil
Probably mainly black peat
topsoil over black organic clay;
greyish brown mottled mineral
soil below
Probably mainly dark clay loam
topsoil grading into dark reddish
brown or yellowish brown clay
loam to clay subsoil
Mostly black peat as in component
2; along stream channels, dark
greyish brown sandy loam to
sandy clay loam with mottled
subsoil where drainage impeded
Classification
Gleyed Podzolic Soils, Humic
Gleys (seepage zone)
Mainly Gn2. - , Gn3. -
Acid Peats
O
Red and Yellow Earths
Um5.52, possibly Gn-
Acid Peats, some Alluvial Soils
O, small areas of Um 1.44, Uc5.21
Surface texture
Loam to clay loam
-
Clay loam
Variable
Surface consistence
Friable when moist
Friable when moist
Friable when moist
Friable when moist
Depth (m)
>1.5
>2.0
0.5 - 1.0
>2.0
Nutrient status
Low
Low
Low
Low
Available soil water capacity
Moderate to high
High
Moderate
Mostly high, some moderate
Perviousness to water
Moderate
Rapid
Moderate
Mostly rapid, some moderate
Drainage
Moderately good, in places very
poor
Very poor
Moderately good to good
Mostly very poor, some good
Exposed stone (%)
Mostly 0
0
<5
0
Sampled profile number
-
-
-
-
NATIVE VEGETATION
Structure of vegetation and
characteristic species of
Dominant stratum
(+ Predominant species)
Shrubby woodland I, II:
E. stellulata+ with or without
E. pauciflora
Open heath:
Baeckea gunniana+,
Epacris spp.+
and Hakea microcarpa
Woodland I, II:
E. stellulata+ with or without
E. pauciflora
Closed forest I:
Leptospermum grandifolium+, or
Melaleuca squarrosa+: Acacia melanoxylon, Nothofagus cunninghamii and Sphagnum spp. sometimes present
Woodland II:
E. stellulata+ with or without
E. pauciflora mostly on high terraces

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
    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; low
    2,4; very low - low
    3: very low
    Uncommon
    Clearing, burning, overgrazing, road building and other earth-moving activities, 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; moderate - high
    2,3; high
    4; moderate

    1; low
    2,4; very low - low
    3; very low
    Uncommon



    Uncommon
    Increased trafficking, overgrazing, 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; low
    2; very low
    3,4; moderate

    4; high
    Uncommon, but locally severe


    Uncommon, but locally severe
    As for sheet and rill erosion above


    As for sheet and rill erosion above
    Increased sediment load and turbidity


    Increased sediment load and turbidity
    Comments: -
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