Buln Buln (Bu)

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

Area: 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 <10°C (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 USE	Mostly 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- cs

A 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
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 and leaching	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; moderate	Uncommon; 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-up	Gully erosion	1,2: low - moderate	Uncommon	As for sheet and rill erosion above	Increased sediment load.
Comments: -

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