As I write this, 8th January, the latest figures for land burnt in Australia stand at 10.7 million hectares. That is an area bigger than Andalucía. Horrific. For people, animals and plant life.
Fire has always been a way of life in Australia, though not like this, on such a scale. The Australian landscape revolves and evolves from fire but there are also other harsh climates, worldwide, where many plants have cleverly adapted to survive it. Some will survive because of their insulating bark, dead leaves or moist tissues. Some trees, such as larch, giant sequoia and our own cork oak have incredibly thick fire-retardant bark; they can be directly burnt without sustaining damage to their internal vital tissues. Only when the fire is extremely intense will they succumb and burn down. Many aloes, yuccas and palms develop thick trunks with dead leaves hanging down to insulate from both heat and cold. And many thick-leaved succulents repel fire with their fleshy moisture-rich leaves which protect the plant from dehydration. Proteas have a covering of corky scales that protect their buds from dessication.
The devastation of a wildfire is mighty but there are many plants that will re-sprout from apparently charred and blackened wood. We see this often around Cómpeta when old olives often re-shoot from totally burnt stumps. In Australia many of the eucalyptus are already shooting vigorously. Some of the banksia species have swollen stems at the base or underground woody tubers, known as lignotubers, from which new shoots can emerge. Similarly there are many herbaceous plants, such as anigozanthus, agapanthus, dietes, dianella and iris, that have fleshy bulbs, tubers or rhizomatous roots underground from which fresh green shoots can emerge – creating a startling contrast to the blackness all around them.
The xanthorrhoea, or grass tree, epitomises the Australian bush – all 66 species of it are endemic to Australia. Many of these have an amazing ability to survive fire; their leaves may burn and their trunks blacken but their living growth point is buried underground, protected by tightly-packed leaf bases. Stimulation by fire will provoke a massive flowering, as the plants take advantage of the ash-enriched soil, determined to make their species survive. Home gardeners have been known to try and imitate this glorious flowering with a blowtorch! Look out, too, for a magnificent blooming of small annual plants that will emerge rapidly after fire – the bush will glow. The aptly named fire lily, cyrtanthus, only flower after fire and respond to it very quickly;
one species can flower within 9 days of a fire.
Another commonly-used anti-burn strategy is that trees will have very tall crowns with no low-hanging branches to be licked by flames. Several pines and eucalypti use this technique that works well when fires are not too severe. The ponderosa pine (pinus ponderosa), a native of North America, constantly drop their dead branches so there’s no ready route for fire.
We know that most seeds will germinate given light, heat and water but there are some (mainly hailing from Australia) that need fire/smoke to germinate – an amazing adaptation to extra harsh conditions. Plants, such as some eucalyptus and banksia, have serotinous cones – that means the seeds are sealed inside the cones by a hard resin – and they can only open to release the seeds when the heat of a fire melts that resin. Ripe seeds can hang within the woody cones for decades until a bushfire passes through. If we want to emulate that, you can put the cones in the oven or over a barbecue and they will slowly open. Remove the seed and plant as normal.
But it’s not just fire that releases seeds; some plants are adapted to react to the chemicals in smoke and charred plant matter that can break seed dormancy. The easiest way to copy this for home growers is by using a bee smoker. Sow the seeds in porous pots, water lightly and put them inside a cardboard box with a few small holes in the top for aeration. Load your bee smoker with dry natural material – some dried grass or leaves – and light it. Poke the nozzle through a hole in the side of the box, pump the smoker and allow the box to fill with smoke. Leave it for about 30 minutes so that chemicals in the smoke reach the seeds.
Gums and wattles (mimosa) dominate the Australian landscape, but it’s the wattle that wins in very arid areas. They survive burning heat, drying winds and long periods of drought. And they have another interesting germination technique. The seeds get, literally, sand-blasted as they’re blown for miles across the desert-like countryside which breaks their tough outer coating, allowing moisture to enter and start the germination process. Copy this at home by placing your seeds in a container with a handful or two of coarse sand and give it a good shaking.
It’s a wonderful world out there and even though we throw disaster after disaster at it, there will always be survivors – or I hope so!
Viveros Florena, Cómpeta, Málaga.
Tel:689928201
Email:florenaspain@hotmail.com
