Fire has been a major transforming force for the forest. When infrequent, fires burn with intense heat due to the heavy build up of fuel on the forest floor. An example of this was the 1968 fire which caused much devastation to the surrounding areas. In recognition of this the Forestry Department had, in 1948, adopted a policy of fuel reduction burns to avoid the excessive damage cause by the hotter fires. These were done in the colder months to reduce the risk of inadvertent spread of the fire and to reduce the heat damage to the forest. A system of fire trails were developed to enable better fire protection and control.
NSW State Forests annually produced fire plans for its forests. The forests which became the Werakata National Park were at particular risk of fire, being close to urban areas. The increased risk came from escaped fires and from arson. The proximity of the forest to urban areas also increases the risk to property and people. In 2002 a forest fire destroyed 13 houses near Abernethy and one man was killed.
The severity of a bushfire, but perhaps more so the frequency of such fires, can effect the balance of species present in the forest.
Different species have different mechanisms of survival during and after a bushfire. Survival mechanisms include:
How quickly a forest regenerates after a fire depends upon numerous factors, including:
- Seeds which may require heat and or smoke to trigger germination
- Seed pods which open after fire, eg Banksia
- Buds which can sprout new growth from the trunk, eg Eucalptus, Melaleuca
- Lignotubers, storage areas in the roots, which provide the nutrients for new growth
- Being able to flee, eg birds and kangaroos.
- Being able to hide from the heat and smoke underground, eg ants.
- What plant species are present, ie are they fire resistant, have they fire-adaptive mechanisms?
- The severity of the fire
- The timing and amount of rain afterwards
- Soil fertility
- The area burnt. It will take longer for non fire-adaptive species to re-colonise from the edges if the area is large.
- How soon after the previous fire. Some species rely totally on the release of seed after a fire. If the next fire comes before they can produce new seed then the species will be wiped out of the area.
In 2001 a fire caused a large section of the northern part of the Park to be burnt and threatened many houses in Abermain.
Below is a series of pictures documenting the forest regeneration after this fire.
This photo was taken on the 9th December 2001.
This was once a spotted gum/ironbark regrowth area (previously logged for mining timber). Before the fire it would have been difficult to walk through here due to the thick undergrowth. It shows how the fire appears to have destroyed most of the forest. The trees remain, but all leaves have died. Initially the ground was covered with only a layer of ash, and was exposed to full sun. There was almost no protection from the wind, and rain could easily erode the soil. Within weeks the old remaining leaves have fallen, providing minimal protection for the soil, and some protection for small animal life. However almost no animal life is to be seen. Some ants are present. The occasional kangaroo track is visible in the soft ash. Life is already returning at this stage. The Macrozamias (grass trees) and Xanthoreas (cycads) have produced green shoots and the earliest of leaves are visible from the Eucalypts and Melaleucas. The Eucalypt leaves are initially red.
This photo was taken on the 23rd December 2001.
It shows green leaves on the iron barks, having sprouted from buds up and down the trunks. The spotted gums are still shedding bark. The larger Melaleucas have sprouted green leaves from the sides of their trunks. The smaller ones have sprouted from the base of the trunk. Some Macrozamias have undergone a prompt response. Some of the smaller ground plants are appearing.
This photo was taken on the 6th January 2002.
The forest is starting to look green again. Still not much shade from the summer heat. Very little ground cover and little protection against erosion. A layer of fine ash still covers the ground. Leaf cover is about the same. Some grasses, and ground covers are starting to appear.
This photo was taken on the 19th January 2002.
Not quite two weeks later, but the leaf growth is obviously greater and there is more shade available. A few grasses have already set seed, perhaps an adaption to capitalise on the reduced competition. A few more ground species make their appearance but are quite small still.
This photo was taken on the 30th June 2002.
Shade is returning to the forest. There is now some protection for smaller birds but still little food. Kangaroos are less vulnerable, given that they are less visible, should they choose to graze the sparse but green ground cover. The trunks of the spotted gums, having shed their bark, now show little evidence of th fire, but the larger ironbarks will keep their blackened colour for decades. Branchlets from the trees are now on the ground. The "fruits" are sill on these branchlets, showing that they survived the heat. They are open, revealing that they have fulfilled their task in protecting the seed and releasing it after the fire.