Gunyah (Gh)

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

Area: 112 sq. km (0.6%)

Hills with ridge-and-ravine topography and moderately long, steep slopes on Cretaceous mudstones, siltstones and sandstones in the South Victorian Uplands are mapped in Gunyah land system. Most occurrences are on the lower parts of the uplifted Balook Block. Landslides have been an important slope process, probably because of the soft porous nature of the sediments and the history of tectonic activity. This land system is similar to Jeeralang in most respects but has lower relief and elevation, and shorter slopes.

A somewhat cool, humid environment, a sedimentary rock that weathers relatively easily and mostly steep slopes, have resulted in uniform and gradational soils with loam to light clay textures. The soils tend to have a medium to fine blocky structure and roots readily penetrate the subsoil horizons. Nutrient status is probably higher than that on most sedimentary rocks in the study area.

The vegetation is mainly E. regnans layered open forest III, with open forest II and III on more exposed aspects or where rainfall is lower.

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

Regenerating forest allows the ridge-and-ravine topography to be clearly visible.

CLIMATE Rainfall, mean (mm) Temperature, mean (°C) Seasonal growth limitations	Annual 900 - 1600; lowest January (60 - 90), highest August or October (120 - 150) Annual 8 - 12, lowest July (3 - 7), highest February (16 - 20) Temperature <10°C (av.): May - September Rainfall < potential evapotranspiration: December - February; occasional winter snow
GEOLOGY Age, lithology	Cretaceous sandstones, mudstones, siltstones and conglomerates of the Strzelecki Group
PHYSIOGRAPHY Landscape Elevation range (m) Relative relief (m) Drainage pattern Drainage density (km/km²)	Steep hills with ridge-and-ravine topography 60 - 500 80 - 200 Dendritic 1.8
PRESENT LAND USE	Mostly uncleared: hardwood forestry; bush grazing of cattle (limited) Minor proportion cleared: grazing of beef and dairy cattle on improved pastures; softwood plantations

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

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

LAND COMPONENT Percentage of land system Diagnostic features	1 65 Steep slopes, with old landslide scars common, and narrow rounded crests	2 15 Less steep lower slopes, often poorly drained	3 10 Broader rounded ridge crests, mostly at lower elevations	4 5 Steeper slopes of gullies and ravines	5 5 Small flats within major drainage corridors
PHYSIOGRAPHY Slope %, typical and (range) Slope shape	35 - 40, (30 - 60) Straight	15 - 25, (5 - 30) Straight	5 - 10, (0 - 15) Convex	Variable, (5 - 20) Straight	2, (0 - 5) Straight
SOIL
Parent material	Mudstone, siltstone and sandstone
Description	Dark greyish brown loam to light clay merging into brown to yellowish brown medium clay	Mostly as for component1; some duplex profiles		No observations — shallow brown soil on steep slopes; humic wet soil in ravine bottoms	Locally derived alluvium Brown sandy loam to sandy clay loam, commonly clay at depth
Classification	Brown Earths Uf6.11, Gn3.21, Gn4.71, Gn4.51	Brown Earths, Grey-brown Podzolic Soils Uf6.13, Gn3.91, Gn4.31, Gn4.51, Dy3.21		- -	Alluvial Soils Um5.52, Gn4.51
Surface texture	Loam to light clay	Loam to light clay		Loam to clay loam	Sandy loam to sandy clay loam
Surface consistence	Hard	Hard		Variable	Slightly hard
Depth (m)	1.0 - 2.0	1.0 -2.0		Variable	>2.0
Nutrient status	Moderate	Moderate		Moderate	Moderate
Available soil water capacity	Moderate	Moderate		Moderate	Moderate
Perviousness to water	Moderate to rapid	Moderate to rapid		Moderate to rapid	Moderate to rapid
Drainage	Good	Moderately good to good		Variable	Variable
Exposed stone (%)	0	0		0	0
Sampled profile number	14, 34	-		-	-
NATIVE VEGETATION Structure of vegetation and characteristic species of dominant stratum (+ Predominant species)	Protected aspects or where rainfall <1100 mm, layered open forest III: E. regnans+ More exposed aspects, or where rainfall >1100 mm, open forest II, III: E. obliqua+, E. globulus+, E. cypellocarpa			Layered open forest III with ferns: E. regnans+, Dicksonia antarctica, Alsophilaaustralis	Shrubby open forest III, IV: E. viminalis+ with or without E. regnans+

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: a) increased deep percolation and leaching b) increased regolith wetness Decreased root-binding	Nutrient loss Soil creep Soil creep	Not determined 1,4; high 2; moderate 1,4; high 2; moderate	Not determined Common: visible on cleared land Common: visible on cleared land	Removal of trees Accelerated by clearing major disturbance of the native vegetation Accelerated by clearing major disturbance of 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	1,2,4; high 3; moderate	Common	Cultivating, logging, burning, 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	12,3,4; high 5; moderate 1,2,4; high 3; moderate	Uncommon Common	Increased trafficking cultivation, overgrazing, export of organic matter As for sheet and rill erosion above	- Increased flash flows
Increased soil disruption	Increased soil break-up	Gully erosion Streambank erosion	1; high 2,3; moderate 5; high	Uncommon: local occurrence Uncommon	As for sheet and rill erosion above As for sheet and rill erosion above	Increased sediment load. Increased sediment load and turbidity of streams
Comments: Regeneration of vegetative cover is quite rapid because of good growing conditions

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