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Banksia (Ba)

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Banksia - geoArea: 26 sq. km (0.1%)

The Banksia land system consists of parabolic dunes and intervening swales along the edges of Seacomhe land system. These dunes have been deflated to varying degrees, with initial aeolian excavation limited in places by the exposure of water tables. In these areas the dunes tend to be low because of the limited sand supply and subsequent erosion. Where the sand sheets are thicker, water tables were not exposed and the dunes are larger. All these dunes and swales, now stabilised by vegetation, are in Banksia land system.

The sandy soils are acidic, infertile and droughty with dark upper horizons, bleached subsurfaces and with iron and/or humus-enriched pans at depth. The soils are susceptible to wind erosion.

The vegetation is mainly heathy or ferny open woodland I. Where water tables are exposed, swamps carry an outer fringe of closed scrub, successively replaced towards the centre by rushland and herbfield, whilst the deepest parts are hare.
A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Banksia - imageHeathy open woodland with Banksia serrata (saw banksia) growing on a low dune near Loch Sport

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

Annual 500-800; lowest January (30-50), highest October (40-70)

Annual 12-14; lowest July (9-10), highest February (19-20)
Temperature <10oC (av.): No months
Rainfall < potential evapotranspiration: November-March
GEOLOGY
Age, lithology

Pleistocene stranded barrier sand deposits
PHYSIOGRAPHY
Landscape
Elevation range (m)
Relative relief (m)
Drainage pattern
Drainage density (km/km2)

Parabolic dunes and swales

0-20
0-20
Nil
0
PRESENT LAND USEMostly uncleared: Mostly within the Lakes National Park and Gippsland Lakes Coastal Park: apiculture
Minor proportion cleared: holiday residential

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

    LAND COMPONENT
    Percentage of land system
    Diagnostic features
1
65
Dunes
2
20
Dry wind-excavated swales
3
15
Swampy wind-excavated swales with concentric vegetation zones
    PHYSIOGRAPHY
    Slope %, typical and (range)
    Slope shape
Variable, (0-30)
Convex, some concave
<1, (0-5)
Concave
<1, (0-5)
Concave
    SOIL
    Parent materials
Wind-sorted sands
Wind-sorted sands
    Description
Dark sand over pale or whitish sand over coffee rock or uncemented bright yellowish brown sand; yellow sand at depth.
No observations – probably black acidic sand over grey sand, possibly with coffee rock at depth where water table is deeper.
    Classification
Podzols
Uc4.32, Uc4.22
Humic Gleys, possibly some Podzols
-
    Surface texture
Sand
Sand
    Surface consistence
Loose or soft
Soft
    Depth (m)
>2.0
>2.0
    Nutrient status
Very low
Very low
    Available soil water capacity
Very low
Very low
    Perviousness to water
Very rapid
Very rapid
    Drainage
Somewhat excessive
Very poor to poor
    Exposed stone (%)
0
0
    Sampled profile number
-Nichoslon (1978) Profile 756
-
    NATIVE VEGETATION
    Structure of vegetation and characteristic species of dominant stratum
    (+ Predominant species)
Inland dunes: heathy open woodland I of E. nitida, Banksia serrata (either predominant): Leptospermum myrsinoides or Thryptomene micrantha dominate the heath.
Swales and dunes near the lakes: ferny open woodland I of E. viminalis var. racemosa, B. serrata or B. integrifolia (close to lakes) and Pteridium esculentum
From margins inwards:
Closed scrub of Melaleuca ericifolia.
Rushland of Juncua maritimus.
Herbfield of Salicornia spp.
Centre often free with water.

    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 leaching.Nutrient loss1,2; high
3; low
Not determinedRemoval of treesIncreased movement of water to groundwater, increased base-flow of streams
    Increased exposure of surface soil
Increased wind velocity over soil and increased detachment of sandWind erosion1,2; high-very highUncommonTrafficking, overgrazing, rabbit burrowing, cultivating, earthmoving activities.Encroachment by sand.
    Increased physical pressure on soil
Increased compactionStructure decline1,2; very low
3; low-moderate
UncommonIncreased trafficking and cultivation, overgrazing, export of organic matter-
    Increased soil disruption
Increased loosening of sandWind erosion1,2; high-very highUncommon, but locally severeTrafficking, overgrazing, rabbit burrowing, cultivating, earthmoving activities, particularly road building.Encroachment by sand
Increased soil break-upWave erosion3; moderateUncommon but locally severe on exposed lake shoresIncreased salinity of water had reduced protective role of Phragmites communisIncreased turbidity of water.
Comments: Regeneration of vegetative cover is poor in areas exposed to wind and wave action; expensive remedial works may be required.
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