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Bulltown Spur (Bp)

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Bulltown spur- geoArea: 132 sq. km (0.7%)

After deposition of the Older Volcanics in the valleys, erosion of the surrounding, softer sediments led to an inversion of the relief and the resistant basalts formed ridge cappings. This new land surface probably formed during the Pliocene. Downcutting by rivers subsequent to the Plio-Pleistocene Kosciusko Uplift has incised and removed most of the Pliocene surface but some relics are perched above the recently formed valleys. Most are dissected remnants of a sloping erosional surface and are mapped in Bulltown Spur land system. Also included are parts of the "pre Older Volcanic" land surface that are too steep and dissected to be included in Wellington and Jamieson land systems.

Soil development shows certain parallels with that in Wellington and Jamieson land systems. Leached, reddish brown soils with little textural change have formed by the action of a cool, humid climate on moderately-resistant parent rock. In Bulltown Spur land system the slopes are steeper and have more natural erosion, thus the soils are usually shallow and stony.

The vegetation is mainly open forest II or III, with woodland I on steeper. rocky slopes at lower elevations. On moderate slopes, understoreys are shrubby or ferny: on steeper rocky sites understoreys are sparse.
A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Bulltown spur- image A gentle crest with Eucalyptus obliqua (messmate stringybark) forest.

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

    Annual 800 - 1400; lowest January or February (40 - 80), highest October (100 - I50)

    Annual 8 - 12; lowest July (3 - 7). highest February (16 - 20)
    Temperature <10C (av.): April - October
    Rainfall < potential evapotranspiration: December - February; occasional winter snow
GEOLOGY
Age, lithology

    Mainly
    Ordovician sandstones, siltstones and shales but also including Carboniferous sandstones, siltstones, conglomerates and Wellington Rhyolites
PHYSIOGRAPHY
Landscape
Elevation range (m)
Relative relief (m)
Drainage pattern
Drainage density (km/km2)

    Hilly to sloping prior landscape remnants

    400 - 1460
    80 - 560
    Dendritic
    1.3
PRESENT LAND USE
    Uncleared: hardwood forestry (timber for general construction and minor timber products); apiculture; bush grazing of cattle (limited); small area in Bogong National Park

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

LAND COMPONENT
Percentage of land system
Diagnostic features
1
100
Complex of slopes and crests of varying steepness and degree of rockiness. This variability combined with variation in aspect and elevation
produces a mosaic of vegetation types differing in structure and composition. No components distinguished
PHYSIOGRAPHIC
Slope %, typical and (range)
Slope shape
30 - 50, (10 - 70)
Straight
SOIL
Parent material
Sandstone. siltstone and shale; some rhyolite
Description
Mostly shallow and stony with dark brown crumb-structured sandy loam to sandy clay loam topsoil grading into reddish brown structureless clay loam or light clay: moderately to strongly acidic
Classification
Red Earths, Lithosols/Red Earths
Um 5.51. Um 5.52, Um 7.11, Gn 2.11
Surface texture
Sandy loam to sandy clay loam
Surface consistence
Soft when dry. very friable when moist
Depth (m)
<0.8 with deeper pockets to 1.5
Nutrient status
Low
Available soil water capacity
Moderate
Perviousness to water
Rapid
Drainage
Good
Exposed stone (%)
<5
Sampled profile number
29
NATIVE VEGETATION
Structure of vegetation and
characteristic species of
dominant stratum
(+ Predominant species)
Structure variable, observed to range from woodland Ito open forest II or III with grassy. ferny or shrubby understories.
Usually mixed stands with variable composition; species include:
Higher elevations — E. dives, E. delegatensis. E. pauciflora. E. rubida
Lower elevations — E. cypellocarpa, E. dives, E. goniocalyx, E. macrorhyncha, E. mannifera, E. obliqua. E. sieberi

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; moderate - highNot determinedClearing, logging, burning, road building and other earth-moving activities.Increased flash flows and sediment load
    Increased physical pressure on soil
Increased compaction

With

reduced infiltration
Structure decline



Sheet and rill erosion
1; moderate



1; moderate - high
Not determined



Not determined
Loss of organic matter, increased soil disturbance.


As for sheet and rill erosion above
-



Increased flash flows
    Increased soil disruption
Increased soil break-upGully erosionl; moderate - highNot determinedAs for sheet and rill erosion aboveIncreased sediment load
Comments: No observations of deterioration
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