Wellington (Wn)

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

Area: 418 sq. km (2.0%)

Wellington land system occurs below the subalpine tract in the East Victorian Uplands, on partially-dissected, prior-landscape remnants that probably predate the Older Volcanics. These remnants have not yet been affected by erosion associated with entrenchment of the modern drainage network. The topography is hilly to undulating and plateau tops are almost accordant. Lithology varies but acid volcanics, metamorphic rocks and slightly-weathered, sedimentary rocks are well represented. Jamieson land system is also mapped on hilly to undulating, prior land surfaces that probably predate the Older Volcanics and which are below the subalpine tract. Plateaux in Wellington land system differ from those in Jamieson, having greater relief and being more humid and densely forested, particularly in the west. The soils have developed on moderately steep slopes and under high rainfall on a variety of parent rocks. There is a predominance of gradational, leached, acidic soils of intermediate texture, moderately to strongly structured throughout. Where slopes are steeper, or the rocks are more resistant to weathering, the soils tend to be shallow and uniform in texture.

Most of the area is covered by open forest II or III, often shrubby or layered, with less vigorous stands on shallow, rocky soils.

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Wellington- image

View across to the gentle to moderate slopes of the plateau suirface

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	Variable; mainly Ordovician undifferentiated sandstones, mudstones and shales, often metamorphosed; Devonian rhyolites and rhyodacites
PHYSIOGRAPHY Landscape Elevation range (m) Relative relief (m) Drainage pattern Drainage density (km/km²)	Partially dissected hilly to undulating prior landscape residuals 560 - 1460 100 - 500 Dendritic 0.9
PRESENT LAND USE	Uncleared: hardwood forestry (mostly ash timber with some timber for general construction); bush grazing of cattle; apiculture

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

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

LAND COMPONENT Percentage of land system Diagnostic features	1 40 Moderate slopes with deeper soils; sedimentary or igneous rocks	2 40 Gentle slopes with deeper soils; sedimentary or igneous rocks	3 15 Slopes of any gradient with shallow rocky soils; mainly Ordovician sediments	4 5 Drainage depressions, often with minor swamps
PHYSIOGRAPHY Slope %, typical and (range) Slope shape	20 - 30, (15 - 50) Straight to concave	5 - 10, (2 - 15) Mainly concave	20 - 30, (15 - 50) Straight to convex	Variable, (10 - 40) Straight, some concave
SOIL
Parent material	Variable; mostly rhyolite, rhyodacite, and siltstone; minor granodiorite		Sandstone, mudstone and shale	Colluvium and alluvium
Description	Mainly dark brown sandy clay loam grading into yellowish brown to reddish brown sandy clay loam to light clay with fine structure, commonly stony; topsoil often deep		Mainly shallow brown stony sandy loam to sandy clay loam	Limited observations — probably dark, undifferentiated with much organic matter and variable texture
Classification	Red and Brown Earths; Krasnozems Gn4.11, Gn4.31, Gn3.11, Gn2.11, Gn4.81, Um4.21, Um6.11, Um6.12, Um6.23, Um7.11		Lithosols, Brown Earths Um-, Um6.23, Uc1.44	Humic Gleys Uc1.24
Surface texture	Sandy clay loam, sometimes loam or clay loam		Sandy loam to sandy clay loam	-
Surface consistence	Soft when dry, friable when moist		Friable when moist	-
Depth (m)	Generally 1.0 - 2.0		<0.8	-
Nutrient status	Low to moderate		Low	Probably low
Available soil water capacity	Moderate		Low	Probably moderate
Perviousness to water	Rapid		Slow to moderate	Probably rapid
Drainage	Good		Good	Very poor to poor on alluvium; better on colluvium
Exposed stone (%)	Often 0, but 5 - 30 not uncommon		Probably >10	Probably 0
Sampled profile number	32	-	-	-
NATIVE VEGETATION Structure of vegetation and characteristic species of dominant stratum (+ Predominant species)	Mostly open forest II, III, often shrubby or layered: Mixed or pure stands with composition dependent on elevation and aspect; Higher elevations — E. delegatensis, E. dives, E. pauciflora, E. radiata, E. rubida Lower elevations — E. cypellocarpa, E. dives, E. obliqua, E. regnans,		Open forest I or II: species including — and occasionally E. nitens, E. viminalis	Limited observations — probably open forest I of Leptospermum grandifolium

Disturbance	Affected process and trend	Primary resultant deterioration			Causal activities	Primary off-site process
Disturbance	Affected process and trend	Form	Susceptibility of components	Incidence within components	Causal activities	Primary off-site process
Alteration of vegetation: — reduction in leaf area, rooting depth and/or perenniality — reduction in density of tree roots	Reduced transpiration, resulting in: a) increased deep percolation b) increased regolith wetness Decreased root-binding	Not determined Soil creep Soil creep	Not determined 1; moderate 1; moderate	Not determined Uncommon: observed occasionally on steep slopes as a natural process Uncommon: observed occasionally on steep slopes as a natural process	Removal of trees Usually after the removal of trees from steeper land Accelerated by major disturbance to the native vegetation	Increased movement of water to groundwater; increased base-flow of streams Increased sediment load Increased sediment load
Increased exposure of surface soil	Increased overland flow and soil detachment	Sheet and rill erosion	1,3; moderate 2; low - moderate	Uncommon: locally severe	Clearing, logging, burning, overgrazing, road building and other earth-moving activities, trafficking by stock.	Increased flash flows and sediment load.
Increased physical pressure on soil	Increased compaction With Reduced infiltration	Structure decline Sheet and rill erosion	1,2; moderate 3; low 4; moderate – high 1,3; moderate 2; low - moderate	Uncommon Uncommon: locally severe	Increased trafficking, export of organic matter As for sheet and rill erosion above	- Increased flash flows
Increased soil disruption	Increased soil break-up	Gully erosion	1,2,3,4; moderate	Uncommon	As for sheet and rill erosion above	Increased sediment load.
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