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Bennison (Bs)

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Bennison- geoArea: 296 sq. km (1.5%)

Bennison land system is mapped on plateaux occurring in subalpine areas and occasionally extending into the upper montane tract. The plateaux are perched above the major areas of ridge-and-ravine topography. Lithology varies and includes sedimentary rocks, their metamorphic equivalents and intrusive igneous rocks. High-elevation plateaux on basalt are mapped in Nunniong land system. The slopes of the plateaux are low although the local terrain is hilly to undulating. A number of lakes, most of which have been drained through natural causes, hogs and drainage depressions are mapped in Moroka land system. Where these drainage areas are too small to be mapped at 1:100,000, they have been included as a component of Bennison land system.
A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Bennison- image
Plateau north of Mount Tamboritha with undulating terrain characteristic of Bennison land system.
A cold climate and high rainfall have combined to produce soils that are friable and acidic, with a high concentration of organic matter in the topsoil and little textural change down the profile. The most common parent rock types are low in plant nutrients and this is reflected in the soils. The more protected parts of this land system tend to have deeper, more humus-enriched soils, with stronger structural development and a higher degree of profile differentiation.

The vegetation is mainly shrubby woodland I or II. with shrubby or grassy open forest II. III or IV on more protected sites. Tussock grassland occurs in wetter areas or on the flanks of ancient lakes. Heaths, sedges and mosses grow in hogs.

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

    Annual 900 - 1600: lowest January or February, highest August or September (150 - 180)

    Annual 4 - 8; lowest July (-2 - 0), highest February (II - 13)
    Temperature <10C (av.): April - October
    Rainfall < potential evapotranspiration: February; frequent winter snow
GEOLOGY
Age, lithology

    Palaeozoic shales, sandstones and related metamorphic rocks; minor areas of rhyolites and rhyodacites and granites and granodiorites. Basalt excluded
PHYSIOGRAPHY
Landscape
Elevation range (m)
Relative relief (m)
Drainage pattern
Drainage density (km/km2)

    Hilly to undulating terrain

    940 - 1600
    40 - 240
    Dendritic
    1.2
PRESENT LAND USE
    Uncleared: summer hush grazing of cattle; recreation — bushwalking, skiing; apiculture; hardwood forestry (ash timber); small area in Bogong National Park

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

LAND COMPONENT
Percentage of land system
Diagnostic features
1
40
Slopes with woodlands
2
35
Slopes with forests
(non E. delegatensis species)
3
10
Non-timbered slopes adjacent to drainage depressions may be flanks of prior lakes.
4
10
Slopes with forests of
E. delegatensis
5
5
Drainage depressions and valley flats, often boggy, with terraces
PHYSIOGRAPHY
Slope %, typical and (range)
Slope shape
5 - 10, (0 - 30)
Straight to concave
10 - 15, (0 - 30)
Concave
Variable, (0 - 10)
Convex
10 – 20, (0 - 40)
Concave
<5, (0 - 10)
Straight
SOIL
Parent material
Shale, sandstone: some related metamorphic rock; minor rhyolite and rhyodacite
Description
Very dark loam to sandy clay loam merging into reddish brown or yellowish brown loam to sandy clay loam, often stony throughout
Dark brown to black sandy clay loam merging into dark greyish brown sandy clay loam, often shallow
Very dark loam to clay loam merging into brown loam; may be stony. Soils deeper than in components 1 and 2
Colluvium and alluvium Variable: generally shallow organic loams over grey or yellowish brown mineral soil
Classification
Mainly Red Earths; Brown Earths and some Lithosols
Um5.52, Um5.51, Um6.12, Um6.24, Um7.11. Um4.31, Uc5.21. some Gn- and Um 1-.
Brown Earths
Um5.21. Um 1.43
Brown Earths; Alpine Humus Um6.12. Um7.11
Humic Gleys, Alluvial Soils: shallow Peat in places
0, Uc1.44. Um5,52
Surface texture
Loam to sandy clay loam
Sandy clay loam
Loam to clay loam
Variable
Surface consistence
Soft to slightly hard
Slightly hard
Soft to slightly hard
-
Depth (m)
0.4-1.5
0.3-0.8
1.0-2.0
0.3- 1.0
Nutrient status
Low
Low
Low
Low
Available soil water capacity
Moderate
Moderate
Moderate to high
High
Perviousness to water
Moderate to rapid
Moderate to rapid
Rapid
Rapid
Drainage
Good
Somewhat poor to good
Good
Very poor to somewhat poor
Exposed stone (%)
Variable: 0 - 50
0 - 10
Variable: 0 - 50
0 - 10
Sampled profile number
-
-
-
-
NATIVE VEGETATION
Structure of vegetation and characteristic species of dominant stratum
(+ Predominant species)
Shrubby woodland I, II:
E pauciflora+ and/or
E. rubida+
Shrubby or grassy open forest II:
E. pauciflora+ with or without E. dives: E. dives+; E. rubida+
Tussock grassland: Poa spp.+, Restio spp.
Heath:
Hakea microcarpa+.
Helichrysum hookeri+
Shrubby or grassy open forest III. IV:
E. delegatensis+, E. rubida+
Better drained sites either with shrubby open woodland I. lI of pure or mixed stands of E. pauciflora, E. rubidia, E. stellulata or with tussock grassland of Poa spp.
Bogs with Baeckea gunniana+, Calorophus lateriflorus and Sphagnum cristatum+

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:


a) increased deep
percolation

b) decreased fog drip


c) increased rate of snow
melt


d) increased depth of
soil freezing




Nutrient loss


-


-



Solifluction




Not determined


-


-



1; low




Not determined


-


-



Uncommon




Removal of trees




Increased movement of water to groundwater; increased base-flow of streams

Decreased stream base flow


Increased spring and decreased summer stream flow

-

    Increased exposure of surface soil
Increased overland flow and soil detachment




Increased frost heave and soil detachment
Sheet and rill erosion




Wind and sheet erosion
1,2,3.4; low





1.2; low
Uncommon: locally severe





Uncommon
Clearing, logging, road building and other earth-moving activities, trafficking by stock and vehicles.

Clearing, logging, road building and other earth-moving activities, trafficking by stock and
vehicles.
Increased flash flows and sediment load.




Increased sediment load
    Increased physical pressure on soil
Increased compaction

With

reduced infiltration
Structure decline



Sheet and rill erosion
1; low - moderate
2.3.4: moderate - high

5; high
1.2.3.4: low
Uncommon; locally severe particularly in cattle camp areas


Uncommon: locally severe
Increased trafficking by stock, humans and vehicles


As for sheet and rill erosion above
Increased spring and decreased summer stream flow


Increased flash flows and sediment load
    Increased soil disruption
Increased soil break-upGully erosion


Streambank erosion
1.2.4.5; moderate
3; low

5: moderate
Uncommon


Uncommon; locally severe
As for sheet and rill erosion


Trafficking by stock and humans, increased stream flow
Increased sediment load.


Increased turbidity of streams
Comments: Regeneration of vegetative cover on higher-elevation. More exposed sites is slow and difficult because of the unfavourable climate.
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