Healthy Land and Water

Fire, grazing and the landscape

• Fire historically part of landscape for thousands of years –BUT we have changed this!

• Most Australian ecosystems have evolved with fire.

• Appropriate fire is important, it aids in maintaining species diversity & persistence & ecosystem function.

Australian Ecosystems

• However, there are tolerance limits - both too frequent & too infrequent fire can be a problem.

• Importantly, different vegetation types have different fire needs (i.e. grassy=frequent & rainforest=exclusion).

Australian Ecosystems

Plants, Animals & Fire

• Fire can:

• open canopy & provide rich ash bed for seedling growth;

• create hollows;

• trigger seed release, germination & flowering; &

• aid in weed management.

Plant Responses to Fire

• Plants respond to fire in many ways, some survive ( thick bark, tubers) others are damaged but flourish in post-fire conditions; some are killed but fire stimulates reproductive response & some die.

• Two groups: (1) Seeders & (2) Resprouters.

Plant Post-Fire Responses

• Plants respond to fire & the post-fire environment in five main ways.

– (1) Increased growth (e.g. grasses);

– (2) Stimulated or increased flowering (e.g. grasstree & Christmas Bells Blandfordiagrandiflora);

– (3) Triggers seed release (canopy/woody capsules) improved post-fire seed dispersal;

– (4) Improved germination soil-stored seeds; and

– (5) Improved seedling establishment.

The Fire Regime - Four Parts

Variation…variation…variation!

Fire Frequency

• Generally defined as years between fires, or the number of fires in a given time.

• Intervals need to be long enough for obligate seeding plants to grow to reproductive maturity.

• Both too frequent & too infrequent is problem, aim for range intervals based on best available information (i.e. plant life history, fauna responses).

• Frequent fires reduce shrub cover & encourage grasses –longer intervals between fires encourage a shrubby layer.

• Patchiness provides:

• refuges for animals;

• food for the first few months post-fire; &

• a seed source for plants.

• Aim for a range of age-classes.

• Look at variety of vegetation types within a landscape (i.e. work with your neighbours).

Fire Extent

Fire Intensity

• Intensity related to topography, fuel loads, moisture , season & weather

• Hotter fires are more destructive – cooler fires more patchy …..

• But some plants/communities require hotter fires

• Fires are safer in the cooler months.

• Consider:

• breeding times for birds and animals;

• dormant insects; &

• seed sources for recolonisation.

• Some variability in season is recommended.

Fire Season

Rainforests & riparian vegetation - Fire exclusion recommended

Recommended Fire regimes

Open woodlands & forests with shrubby understorey –suggested to vary intervals between 7–25 years. Low to moderate intensity.

Grassy woodlands & open forests suggested vary intervals between 3–6 years. Low to moderate intensity

Recommended Fire regimes

Landscape Values

ForestryConservation

LifestyleGrazing

Forestry

Conservation

Why burn ?

Why burn ? Benefits of planned fire

• Improve pasture quality & vigour – remove old moribund pasture & promote new growth for improved performance

• Enhance pasture condition - Encourage desirable 3 P pasture species & discourage some undesirable pasture species eg wiregrass

• Manage grazing pressure – improve utilisation, evenness & reduce patch grazing

• Control woody weeds like Lantana, weedy shrubs and forbs and help keep regrowth in check to maintain grassy understorey

• Mitigate against wildfires – firebreaks, mosaic burns = reduce fuel loads to prevent untimely loss of pasture, damage to infrastructure , soil loss , damage to forest/ timber values , loss of biodiversity

• Improve land condition and biodiversity

Why burn ? Risks of inappropriate/unplanned fire

• Can lead to soil erosion through loss of or reduced surface cover

• Soil fertility & pasture condition decline through loss of cover, organic matter & soil biology

• Immediate loss of forage - feed shortage for stock

• Damage to fences & other property infrastructure

• Wrong regime ( frequency, intensity ) can promote some undesirable species

• Damage to timber resources

• Loss or degradation of native vegetation & habitat

Benefits / risks – so what to do ……

• Well planned & managed fires have positive benefits for grazing and timber production

• Also maintains biodiversity values - achieving balance -between production & conservation.

• Identify the right fire regime for land types, pasture & native vegetation to meet your goals• Frequency – how often• Season - when• Intensity – how hot related to flame height, fuel load, weather (season),

moisture

• Patchiness – how much (burning mosaic)

Improving pasture composition & condition

Increasing desirable 3 P grasses• Black speargrass

• Kangaroo grass

• Forest bluegrass

• Qld bluegrass

• Scented top

• Tambookie grass

Decreasing undesirable pasture species

• Wiregrass

• Blady grass *

• Pasture weeds

Improving pasture composition & condition

Improving land condition -

Controlling woody weeds Reducing shrub / regrowth

Rest at critical times is key

Phase 1 - Early growth

Post fire spelling – growth response

Maintaining groundcover & organic matter

Groundcover management

Groundcover is defined as anything that breaks the fall of rain up to 30cm above the ground, including pasture, leaf litter, dung, biological soil crusts, sticks & rocks.

• Maximises infiltration and minimises erosion of precious topsoil & runoff

• Insulates soil surface from drying winds and evaporation to retain moisture and protect microbes

• Buffers soil temperatures to maximise microbial activity

• Helps minimise invasion/colonisation by annuals or weeds

• Provides organic matter for soil & microbes

• Provides habitat for variety of ground dwelling fauna

Ground cover management

Ground cover percentage 87 69 6

Runoff (mm of rain) 1.5 14 38

Soil loss (t/ha) 0.03 0.3 22

Sediment lost with run-off (g/L) 1.5 1.9 63

When and how much fire?

Plans for each paddock - land types, vegetation, pasture condition, generally ….

• Burn grassy woodlands & grassy open forest 3 - 6 years interval

• Burn late dormant season & early growing season depending on season with adequate soil moisture

• Burn after decent rainfall ( 25 – 30 mm) & aim to retain mulch on soil and protect plant crowns

• Need around 1 500 kg /ha + to carry reasonable fire after moisture – 2 000 kg + for controlling woody weeds, regrowth

• Burn in mosaic pattern – not all at once (but not too little to avoid patch grazing)

• Critical to manage overgrazing of new growth after fire

• Risks with fires too hot, or too frequent - lose nutrients, cover, plants, timber & habitat

Forest management fires

• Reduce fuel loads and risk of wildfires damaging forest and timber resources

• Encourage tree growth & regeneration

• Interrupts growth of re-sprouters<2m tall

• Encourage pastures and reduce weeds

• Influences biodiversity

Forest management fires

• Aim for lower intensity cool burns to protect from scorching of crown, wood defects

• Must be planned – consider fuel load, moisture, forest type , erosion risk , purpose

• Burn using mosaic pattern – variability in regime (timing, intensity, frequency) to maintain biodiversity

• Regeneration depends on forest type –seeders like Blackbutt require higher intensity fire for disturbance

In summary

• Fire very important management tool but a poor master !

• Benefits : improves pasture quality, vigour & new growth , promotes desirable grasses, controls weeds & regrowth, manage grazing pressure, wildfire mitigation , improve biodiversity values.

• MUST BE PLANNED, PURPOSE , MANAGE & MONITOR • Soil moisture – burn after 1 to 2 inches (25-50mm) of rain

• Just before 2- 3 inches of gentle follow up rainfall !!!!

• PLUS capacity to rest / reduce grazing

• Burn rotationally (not entire property, but not too little, mosaic)

• Appropriate fire regimes for situation• Frequency, Season, Intensity, Extent

Questions

2019 Drought Fires

Post 2019 fire recovery

Post 2019 fire recovery

Post 2019 fire recovery

Post 2019 fire recovery

Post 2019 fire recovery - dry rainforest