Blomford (Bf)

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

Area: 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 <10°C (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- cs

A 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
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 — 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 detachment	Sheet and rill erosion	1.2: high	Common	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: 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-up	Gully erosion	12: high	Uncommon	As for sheet and rill erosion above	Increased sediment load.
Comments: -

Page top