Lecture 3 - Native Pastures Classification + Distribution

COMMON CHARACTERISTICS OF NATIVE PASTURES

• Generally grasses of lower quality compared to introduced species.

• Most are diverse with many grass species (Speargrass pastures) but a few contain monocultures of almost single species (Mitchell grass pastures).

• Some nutritious native legumes/herbs grow in native pastures but they may disappear under grazing.

• Pastures in woodlands contain shrubs/trees that are sometimes browsed.

• Most native pastures can contain plants that have toxic properties

The 3P in 3P grasses stand for what?

Perennial, Productive, Palatable grasses

What are the grazing resources in native pastures?

• Native perennial, productive, palatable grasses (3P grasses) – decreasers under grazing.

• Native perennial grasses (not preferred – e.g. wire grass) – increasers under grazing.

• Annual grasses – increasers under grazing (less preferred – e.g. grader grass)

• Forbs (small component, but can be palatable)

• Shrubs (mostly unpalatable but some can be useful e.g. mulga)

Classification of Native Pastures is based on what 3 things?

• Appearance (tall or short)

• Vegetation characteristics (grasslands, woodlands, shrublands)

• Climate (humid to arid)

Comments on each

• Tallgrass zone

• Speargrass zone

• Mitchell grass

• Mulga country

• Spinifex

• Brigalow zone

• Tallgrass zone in northern Australia (e.g. Cape York) – produces large biomass of grass but is of low quality

• Speargrass zone – very important for northern beef production

• Mitchell grass – excellent native pasture (Astrebla species), traditionally sheep country

• Mulga country – sparse pasture but mulga is an edible fodder tree used for drought feeding

• Spinifex – very large areas, low rainfall, poor capacity for grazing

• Brigalow zone – Originally native acacia tree growing on fertile black soil, but cleared for crops and improved pastures

HUMID SAVANNA - INDONESIA

• Short dry season.

• >700 mm rainfall/year.

• Woody plants originally present as tall trees or shrubs.

• Regular burning.

HUMID SAVANNA - PNG

• Markham Valley

• Trees originally

• Cleared and burnt

• Pasture grazed by cattle

• High potential for degradation

Subhumid Savanna - Northern QLD + Brigalow zone

• This shows what the Brigalow zone used to look like before it’s been cleared

Brigalow Pasture - that has been cleared

Subhumid Savanna - Southeast QLD

• Short dry season.

• 500-700 mm rainfall/year.

• Woody plants usually present as tall trees or shrubs.

• Regular burning

• ***Black speargrass zone

MONSOON TALLGRASSWOODLAND – MT GARNET

• This grass grows a little bit taller

• In Northern QLD

• Still a black speargrass zone but with higher rainfall

MONSOON TALLGRASS – NORTHERN AUSTRALIA

• lots of grasses but NOT a lot of nutritional value because the soils have been depleted of nutrients over time

• Don’t always associate lots of grass with healthy cows

• Landowners would give supplements to their animals in this type of pasture

SEMI ARID SAVANNA – MULGA (ACACIA ANEURA)

• Long dry season.

• <500 mm rainfall/year.

• Woody plants usually present as low shrubs.

• irregular burning.

Lightly grazed mulga - Charleville

• Southeast QLD

• Mulga is the tree

Mulga leaves are palatable but have low quality

• Cattle will eat when they need to but they prefer not to

Drought in Charleville

• a landowner knocked some mulga trees down to feed sheep during the drought

• need approval to cut mulga trees down

SEMI-ARID SAVANNA – MITCHELL GRASSLANDS

Arid Savanna - Spinifex (Triodia spp.)

• Ayer’s Rock

Channel country after floods

• Western QLD - a lot of area gets really low rainfall (only a couple 100mm)

• When you get lots of rain in places like Northern QLD, all the water actually runs inland instead of out to sea + creates channels that filter out of river systems

Some main differences between Mitchell grasslands, Spear grass (tropical + subtropical tallgrass) and Monsoon tallgrass

Mitchell grasslands

• Lowest annual rainfall compared to the other two (only 250-550 mm/year)

• Soil Type: Cracking Clay (Fertile)

• Good resilience under grazing

• No Trees

• Grass Species: Astrebla spp, Iseilema spp.

Spear grass (tropical + subtropical tallgrass)

• Middle annual rainfall out of the 3 (650 - 850 mm/year)

• Soil Type: Texture Contrast (Infertile)

• Moderate resilience under grazing

• Trees: Narrow Leaf Ironbark, Silver Leaf Ironbark, Blue gum

• Grass Species: Heteropogon, Bothriochloa, Themeda, Aristida

Monsoon tallgrass

• Highest annual rainfall out of the 3 (700 - 1500 mm/year)

• Soil Type: Massive Earth, Stony, Sandy Soils (Infertile)

• Poor Resilience under grazing

• Trees: Eucalypts, Teetree, Ironwood

• Grass Species: Sorghum, Themeda, Sehina, Chrysopogon

Temperate Rye Grass Pastures - NZ

• Ryegrass is most prevalent one used in temperate pastures

• Use ryegrass during autumn for when Kikuyu grass starts to die

• Introduce different species to get an all year round supply because each species has different growth requirements

Temperate Rye Grass - Clover Pastures (NZ)

• you can also add a nice legume (like clovers) to temperate pastures