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Buln Buln (Bu)

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Buln Buln- geoArea: 28 sq. km (0.1%)

In the west of the study area near Buln Buln East, areas of Devonian and other Palaeozoic sediments, exposed by removal of Older Volcanics. have been mapped in Buln Buln land system. Areas still covered with basalt are in Neerim land system. In some areas, exposure of the Palaeozoic sediments occurs only in valley floors where drainage has incised the basalt. Landform consists of rounded hills and alluviated valleys very similar to those of Neerim land system.

Mostly fine-textured. sedimentary rocks and their slightly-metamorphosed counterparts and a moderate to high rainfall produced deep soils with significant amounts of clay. The soils are generally leached and acidic, with lighter-textured topsoils overlying mottled, clayey subsoils. Some basaltic influence may occur locally where material from Neerim land system has been deposited.

The remnant native vegetation is mainly open forest II. with a shrubby woodland I in drainage lines. Similar forests probably occurred in the areas that have now been cleared.
A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Buln Buln- image
Characteristic low hills with relatively gentle slopes and rounded crests; sedges now grow in the cleared valley that probably once carried Eucalyptus ovata (swamp gum).

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

Annual 700-1200: lowest January or February (40 - 70). highest August or October (90 - 120)

Annual 12 - 14; lowest July (8 - 10). highest February (19 - 21)
Temperature <10C (av.): May - September
Rainfall < potential evapotranspiration: December – February
GEOLOGY
Age, lithology

Devonian sandstones, mudstones, shales and slates (Centennial Beds and Coopers Creek Formation, also undifferentiated Tanjil Formation)
PHYSIOGRAPHY
Landscape
Elevation range (m)
Relative relief (m)
Drainage pattern
Drainage density (km/km2)

Slopes, rounded hills and alluviated valley floors

80 - 260
40 - 100
Dendritic
1.6
PRESENT LAND USEMostly cleared: grazing of beef and dairy cattle on improved pasture.
Minor proportion uncleared: hardwood forestry (timber for general construction); apiculture

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

LAND COMPONENT
Percentage of land system
Diagnostic features
1
80
Slopes and rounded crests
2
20
Waterlogged valley floors, often channelled
PHYSIOGRAPHY
Slope %, typical and (range)
Slope shape
12 - 18, (0 - 30)
Mainly convex
<2. (0 - 5)
Straight
SOIL
Parent material
Mudstone, shale, sandstone and slate
Mainly fine-textured alluvium
Description
Limited observations — dark greyish brown often fine structured sandy loam to clay loam topsoil over mottled yellowish brown blocky structured clay subsoil
Limited observations — probably mainly moderately heavy textured topsoil over blocky strongly mottled yellowish brown clay subsoil: possibly slightly alkaline
Classification
Yellow Podzolic Soils or intergrades with Xanthozems
Dy3.21, Gn4.81
Possibly Wiesenboden
-
Surface texture
Sandy loam to clay loam
Probably silty loam to clay loam
Surface consistence
Friable when moist
Friable when moist
Depth (m)
>2.0
>2.0
Nutrient status
Low to moderate
Low to moderate
Available soil water capacity
Moderate
Moderate
Perviousness to water
Slow to moderate
Slow to moderate
Drainage
Somewhat poor to good
Poor
Exposed stone (%)
0
0
Sampled profile number
-
-
NATIVE VEGETATION
Structure of vegetation and
characteristic species of
dominant stratum
(+ Predominant species)
Limited data — probably mainly open forest II with E. obliqua+:
E. dives and/or E. cypellocarpa often associated
Limited data — probably mainly shrubby woodland I of E. ovata.
Leptospermum juniperinum and Melaleuca squarrosa in the understorey

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 and leachingNutrient lossNot determinedNot determinedRemoval of treesIncreased movement of
water to groundwater:
increased base-flow of
streams
    Increased exposure of surface soil
Increased overland flow and soil detachmentSheet and rill erosion1; moderateUncommon; local
occurrence mainly on
cleared land
Clearing, cultivation,
burning. overgrazing.
road and dam 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; low - moderate
2: high


1. moderate
Uncommon



Uncommon: local
occurrence mainly on
cleared land
Increased trafficking and cultivation, overgrazing, export of organic matter

As for sheet and rill erosion above
-



Increased flash flows
    Increased soil disruption
Increased soil break-upGully erosion1,2: low - moderateUncommonAs for sheet and rill erosion aboveIncreased sediment load.
Comments: -
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