Moroka (Ma)

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

Area: 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 <10°C (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 USE	Mostly uncleared: bush grazing of cattle; apiculture (limited)

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

A 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
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; 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
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