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Blomford (Bf)

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Blomford- geoArea: 318 sq. km (1.6%)

Terrain within this land system is formed on granites. granodiorites, gneissic metamorphics and related coarsely-crystalline, plutonic rocks. Topography is mountainous, with long, steep slopes, rock outcrop and a ridge-and-ravine dissection pattern. In these respects Blomford is similar to Baldhead land system; however, Blomford is mapped in the much drier areas which occur mainly at lower elevations, and is more limited in extent. Small levees and alluvial flats (similar to Walnut land system but not mappable at 1:100,000 scale) occur occasionally along a few major streams, notably the Timbarra River.

The Blomford land system has relatively slow rock weathering and high, natural erosion rates due to incomplete vegetative cover and steep slopes. This has resulted in shallow soils that are weakly aggregated or apedal throughout and moderately acidic.

The vegetation is open forest I or II with sparse understoreys.
A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Blomford- image
The partly cleared steep slopes on the resistant metamorphics of Blomford land system are part of the metamorphic aureole surrounding the lower, more gentle slopes of Dargo land system which have formed on deeply weathered plutonic rocks.

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

    Annual 700 - 1200: lowest January or February (40 - 80), highest October (100 - 150)

    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

    Palaeozoic granites, granodiorites. gneissic metamorphics and related coarsely crystalline plutonic rocks
PHYSIOGRAPHY
Landscape
Elevation range (m)
Relative relief (m)
Drainage pattern
Drainage density (km/km2)

    Steep mountains with ridge-and-ravine topography

    220 - 920
    80 - 400
    Dendritic
    0.5
PRESENT LAND USE
    Uncleared: hardwood forestry (minor timber products); apiculture; some bush grazing of cattle

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

LAND COMPONENT
Percentage of land system
Diagnostic features
1
85
Slopes with drier forest
2
15
Slopes with moderately humid forest
PHYSIOGRAPHY
Slope %, typical and (range)
Slope shape
30 - 50. (20 - 80)
Straight
40 - 50. (30 - 80)
Straight
SOIL
Parent material
Granite. granodiorite and gneissic metamorphic rock
Description
Dark greyish brown loam to loamy sand topsoil grading into brown and slightly reddish brown subsoil of variable texture (clay to sand): generally very stony and shallow
Dark greyish brown sandy loam topsoil grading into slightly reddish brown to yellowish brown subsoil of variable texture (sandy clay to coarse sand); generally stony but deeper than in component 1
Classification
Lithosols
Um1.23. Uc5.21. Gn3.21
Lithosols
Um5.51. Uc1.42. Uc5.21
Surface texture
Loam to loamy sand
Sandy loam
Surface consistence
Slightly hard when dry
Soft to slightly hard when dry
Depth (m)
<1.0
<1.2
Nutrient status
Low to moderate
Low to moderate
Available soil water capacity
Low
Low to moderate
Perviousness to water
Rapid
Rapid
Drainage
Good
Good
Exposed stone (%)
<50
<20
Sampled profile number
-
-
NATIVE VEGETATION
Structure of vegetation and characteristic species of dominant stratum
(+ Predominant species)
Open forest I, II: E. macrorhyncha and/or E. sieberi generally predominant: E. goniocalyx, E. rubida and E. globoidea (less frequently) associated
Open forest II (denser understorey than in component I ): Mostly E. dives+, occasionally E. obliqua+; E. pauciflora (higher elevations). E. goniocalyx. E. globulus and E. cypellocarpa associated

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

    — reduction in density of tree roots
Reduced transpiration, resulting in increased deep percolation and leaching

Decreased root-binding
Nutrient loss



Soil creep
1,2: moderate



1; high
Not determined



Uncommon: but isolated instances
Removal of trees



Accelerated by any major disturbance of the native vegetation
Increased movement of water to groundwater: increased base-flow of streams

Increased sediment load
    Increased exposure of surface soil
Increased overland flow and soil detachmentSheet and rill erosion1.2: highCommonClearing, 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: low



1.2: high
Uncommon



Common
Increased trafficking and overgrazing



As for sheet and rill erosion above
-



Increased flash flows
    Increased soil disruption
Increased soil break-upGully erosion12: highUncommonAs for sheet and rill erosion aboveIncreased sediment load.
Comments: -
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