Text taken from the catalogue Phoenix
ISBN 0 9581792 0 4

Fire and Flora
Text by Mark Ooi Fire Ecologist NSW Australia

Fire, regeneration and rejuvination. Some people have penned it as our Phoenix flora. Here in south - eastern Australia, fires are a natural and recurrent part of our ecosystems. The ecology and evolution of our plant communities have been heavily influenced by fire. Plant populations have developed different methods for persisting through fires and for some fire is a necessity. There is a stark and silent beauty attached to recently burnt parts of our natural environment. The scorched earth scene however, is really just a short step in this post - fire dynamic. If you start looking closely, there is a city - sized buzz of activity going on.

The first thing you notice are the Eucalypts. Within weeks of fire, they are resprouting from epicormic buds protected from the fire under insulating bark. This flush of new growth covering them from trunk to branch tips alienises a familiar image. Other plants, like some Tea - trees (Leptospermum species), resprout from underground lignotubers, with fresh, soft growth clustered around the base of charred stem remains. Bright green sedges quickly carpet the charred ground.

Look up and you'll see 5 metre flowering spikes of the giant Gymea lillies (Doryanthes excelsa). Fire stimulates plants like these to flower. These pyrogenic wonders, resprout at world record pace, then shoot out flowering spikes ready for pollination and a subsequent mass of new seeds. Also up high, you'll see cones and woody fruit on the branches of adult plants like Banksias. These hold a store of seeds and protect the seeds from lethal temperatures. Those same temperatures also release the seeds, either directly by unglueing the cone follicles or indirectly with the death of the adult stems.

Get down on your hands and knees and you start to see seedling emergence en masse. There is a wealth of information down here, a lot of it contained in the soil seedbank. In between fires, plants produce seeds and the seeds fall and collect up in the soil. Within these seeds are the genetic code of generations of plants and the key to a species persistence. Even with the death (from old age) of the above ground adults in between fires, the seedbank can maintain itself for decades. So the species still exists at that spot, not as plants but as seeds. The passage of fire breaks the dormancy of many seeds. Heat provides the response for seeds like those from Wattles and other legumes, where the hard seed coat is cracked by fire induced high temperatures. Smoke induces the germination of other species such as some Grevilleas. Both of these mechanisms ensure that the seedlings come up into a post - fire environment where there is plenty of opportunity to grow, eventually into mature plants, producing new seeds. And the cycle continues.