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Tallong Midge Orchid

The Survivors
by Greg Stone

Fire in the Bush
by Greg Stone

More Road Kill
by Phil Mosies

Injured Native Wildlife
Emergency Management

Goldrush Grog
by Phil Mosies

Spring Purples and Pinks
by Greg Stone

Road Kill Recipes
by Phil Mosies

Penrose General Store

The Spotted Gums
by Greg Stone

Winter Fires
in Tallong

In The Natural Interest

The Survivors
by Greg Stone
As I sit to write this month's contribution, the weather is unusually cold and wet for mid-November, however experience has taught us that just a few hot, windy days can rapidly increase the threat of bushfires. With this in mind, fire in the bush seems to be a relevant topic to explore.

The majority of remnant communities of natural vegetation in the Tallong -Wingello - Penrose - Canyonleigh area occur on dry, well-drained and infertile soils based on Hawkesbury Sandstone, and most of the plant species growing in these fire-prone sclerophyllous (hard-leaved) communities have been specifically made with inbuilt 'bushfire survival' mechanisms. Most of us will have seen a dark and desolate bush landscape remaining after a devastating fire and wondered how anything could survive, let alone recover to flourish again. Yet several years later the same site is again full of green foliage with only the blackened trunks of the Eucalypts testifying to previous events.

How do the plants survive and recover? In regard to fire response, plants divide themselves into two basic groups - the 'sprouters' and the 'seeders' (for want of better names!)

The Sprouters
The 'sprouters' are those plants that respond to fire damage by sending out new vegetative growth. Some of the most common sprouting mechanisms are epicormic buds, lignotubers, rhizomes and underground rootstocks and fire induced flowering.

Epicormic buds
Beneath the bark of many Eucalyptus species are specialised 'epicormic' buds which lie dormant until the canopy of the tree is either removed or scorched by fire. The loss of leaves triggers a burst of growth from these buds (epicormic shoots) which provides an almost immediate leaf growth to sustain life and aid the recovery of the plant. Eucalyptus trunks clothed in fresh, green foliage are a common sight after a bushfire.

Most Eucalypts have a specialised root system in the form of a 'lignotuber'. This is actually a swollen tap root which contains numerous dormant buds protected by the soil surface. Most soils are poor conductors of heat and provide adequate protection to lignotubers. As with epicormic buds, lignotuber buds respond when the upper parts of the tree are damaged by fire. Lignotubers are most common in 'mallees' or smaller, multi-stemmed Eucalypts.

Rhizomes and underground rootstocks
Rhizomes are horizontal underground stems which obviously enjoy the benefit of some protection from fires burning overhead. Plants such as the common Spiny-headed Mat Rush (Lomandra longifolia) may be destroyed by fire, but are afterwards able to send up new shoots from their rhizomes.

Fire-induced flowering
The Grass Trees (Xanthorrhoea spp.) often produce a large flowering stalk immediately after a fire in order continue their regenerative processes as soon as possible.

The Seeders
The 'seeders' obviously survive a bushfire by means of a variety of seed-based methods, which include protective seed-coats, storage in the soil and protection in woody seed capsules.

Hard seeds in the soil
Leguminous shrubs e.g. Acacia (Wattles) and the many members of the Fabaceae (Pea flowers) family are usually destroyed by fire but regenerate from the huge number of seeds stored in the soil or leaf litter. Most legumes produce seeds with a hard coating which is impermeable to water and will therefore not germinate until cracked open by fire. These species are usually the first plants to regenerate after a fire.

Woody seed capsules
Shrub species such as Banksias and Hakeas have the capacity to regenerate from rootstocks as 'sprouters' but also store their seed for many years in thick, woody capsules. A hot fire will often kill the adult plant but also assist in the release of the seeds from the capsules. The capsules are desiccated by the heat and in shrinking release the seeds into an ash bed favourable to germination.

Leptospermums (Tea Trees), Melaleucas (Paperbarks) and Callistemons (Bottlebrushes) employ a similar mechanism, but the smaller seed capsules are not as efficient at retaining seed, and seed-fall may occur every few years whether a fire is present or not.

That's not all...
If time and space permitted, we could also consider the plant species that send in 'air-drops' of wind-borne seeds to germinate in fire-devastated areas. Or perhaps the Burrawangs (Macrozamia spp.) which keep a supply of food buried beneath the ground to enable a quick post-fire response. Or the different ways in which both rough and smooth Eucalyptus bark protects the trunk from fire damage. Maybe later in this fire season we will explore this subject a little further.

Greg Stone
Woodlands Revegetation

C/- P. O. Wingello
Wingello N.S.W. 2579

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