Fire and Forests


Every year there are over 300 fires in our State Forests; yet we never hear of forest being "destroyed" by fire.
In nearly all cases, the burnt area is back to normal within two years.
How is this possible?

Of Fruits and Nuts
The fruit of many forest plants (eg. the eucalypts) are hard and woody, and highly resistant to burning.
The heat of a fire helps to ripen the seeds inside these fruits, and often cause the fruit casing to split.
Over the next couple of days, the seeds drop out onto the newly-cleared soil.
The so-called "honkey nut" of the marri and the large, woody fruits of the banksias are good examples of fire-resistant fruits.

Bark - A Coat for All Seasons
Most of the larger forest plants have a thick, protective bark which will resist all but the fiercest fires.
The eucalypts and casuarinas are good examples of this.
Karri and jarrah trees are among the most fire resistant species in the world.
The insulating bark of jarrah is effective even against very hot fires.

The common blackboy doesn't have bark in the way other trees do.
Its trunk is made up of a dense matting of burnt leaf-bases.
After a fire, the new crown grows on top of the burnt remains of the previous one.
In this way the blackboy increases in height with every burning.

Epicormic Buds
Epicormic-buds are special leaf-buds found just under the bark of the trunk.
Fire damage to the crown stimulates these buds to shoot out from the bark as clumps of foliage, permitting the tree to carry on with its essential functions while the crown recovers.
They are most striking in marri and karri, appearing like a lacework vine climbing up around the trunks.

Rootstock - A Basement Pantry
Many woody-stemmed forest trees have an underground rootstock, or lignotuber, which will send out new shoots if the old trunk is badly damaged.
These shoots, sometimes called suckers, may in time usurp the old trunk if it cannot recover.
Otherwise, once the old trunk is functioning sufficiently, the suckers may deteriorate, die and eventually fall off.
Blackbutt and Jarrahs are vigorous examples of rootstock growers.

The Eternal Seed
The first plants to burn in a fire are those of the undergrowth on the forest floor.
Consequently, the survival of their species depends totally on the copious quantities of seeds they produce early on in their life.
These lie dormant on the soil waiting for a fire to clear the ground-cover and to stimulate their germination.

The Eucalypt Forest

THE OVERSTOREY, or forest canopy
In the overstorey are found the seed capsules and fruit of the large trees, insects of many sorts, and the birds which feed on these foods.
The Port Lincoln Ringneck, or "Twentyeight", which feeds on the pulp of the green eucalypt fruit, particularly that of marri, can often be seen in large flocks high up in the tops of the tall forest trees.


In the branches and tops of the karri oaks, peppermints, banksias, and cedars, birds such as the New Holland Honey-eater and the Western Rosella feed on the insects and seeds, and the nectar from the flowering trees and shrubs in the neighbourhood.


Scrubwrens, Robins and the Fairy-wrens flit through the dense scrub, coming down to the ground in search of food.


The domain of the native mammals and ground dwellers such as the Emu, the forest floor is only sparsely populated in karri forest.
Most mammals are usually found in the more open jarrah, forest and woodlands.

The Trees

Jarrah (Eucalyptus marginata) is the State's most important commercial timber.
It grows to 40 m in height and 2 m in diameter.
Its botanical name "marginata" refers to the thick margin around the leaf's edge.

Marri (Eucalyptus calophylla) is characterized by large gum veins which often break through onto the bark.
It reaches over 40 m in height and 1.5 m in diameter.
The honey produced from the marri flower is very popular, known most commonly as "Red Gum".
The botanical name "calophylla" means "beautiful leaf".

Karri (Eucalyptus diversicolor) is Western Australia's tallest tree, reaching over 80 m in height and 3 m in diameter.
It sheds its bark in a spectacular stripping display over summer.
The botanical name "diversicolor" means "separate colours", and refers to the difference between the top of the leaf and its underside.



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Last updated: Friday, 04.06.2010 1:03 PM