Banksia (Ba)

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

Area: 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 - image

Heathy 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 <10^oC (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 USE	Mostly 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 - cs

A 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
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	1,2; high 3; low	Not determined	Removal of trees	Increased movement of water to groundwater, increased base-flow of streams
Increased exposure of surface soil	Increased wind velocity over soil and increased detachment of sand	Wind erosion	1,2; high-very high	Uncommon	Trafficking, overgrazing, rabbit burrowing, cultivating, earthmoving activities.	Encroachment by sand.
Increased physical pressure on soil	Increased compaction	Structure decline	1,2; very low 3; low-moderate	Uncommon	Increased trafficking and cultivation, overgrazing, export of organic matter	-
Increased soil disruption	Increased loosening of sand	Wind erosion	1,2; high-very high	Uncommon, but locally severe	Trafficking, overgrazing, rabbit burrowing, cultivating, earthmoving activities, particularly road building.	Encroachment by sand
Increased soil disruption	Increased soil break-up	Wave erosion	3; moderate	Uncommon but locally severe on exposed lake shores	Increased salinity of water had reduced protective role of Phragmites communis	Increased 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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