FIRE

Natural Changes:

What determines changes caused by fires?

Fire regimes vary in specific landscapes according to the sequences of fire events rather than a single event

Fire Regime is determined by The Intensity Frequency - which effects the growth cycle of plants Season

Immediate Changes

Examples of Vegetative response: Tree ferns, some eucalypts have epicormic buds

protected by thick bark that sprout new growth when activated – by loss of foliage, damage or intense smoke/heat

Reduction in animal populations during or immediately after fire

Individual animals may die or following the fire through predation due to lack of food available

Creation of open spaces – access to light and nutrient rich seed bed

Grass trees produce flower spikes (and seeds) following fires, scencio – fire weed is one of the first to re-establish

Immediate changes cont...

The biological, chemical and physical effects on soils vary according to intensity and temperature

Generally only top few cm are affected due to high temp

Low intensity fires cause biological effects such as soil sterilisation – death to any living matter

High intensity fires – Over 1000C may alter chemical structure – Nitrogen, Phosphorus & Ammonia

Immediate changes cont...

Soil fertility is increased through breakdown of all natural vegetation

However, may be easily washed away with the loss of vegetation after rain fall

Short Term Changes

Within 3-4 weeks many trees begin to show signs of life – epicormic growth – nodule growth on trunk and underground lignotubers

Changes

Species such as hakeas, banksias, acacias and eucalypts regenerate from seed in ideal conditions - access to light and nutrient rich ash beds during germination

Tree ferns resprout from charred trunks, shrubs resprout from branches, grasses regenerate by rapid growth at the base of the plant