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Blessing in disguise: Can bushfires be good for nature?

Updated Tuesday, 3rd February 2009

Although they look devastating, bushfires can have beneficial effects, as Yoseph Araya explains.

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It is cold winter’s day at my office in Milton Keynes, England; while my field sites in the Cape Floristic Region (Cape Town, South Africa) are enjoying a sunny, hot, dry summer. The Cape Floristic Region is the world’s richest (per size) floral kingdom and a UNESCO world heritage site. If it were possible, I would escape England’s winter and head out there now to enjoy this summer sun. Unfortunately my fieldwork there has to be done in their cold damp spring (September-November) when I record all the different plant species coming up, just at the end of the winter rains.

But not all is rosy down there right now, as it is a tense and often busy time for nature reserve managers. This is all because of the ever present risk of bushfires. Bushfires occur frequently in such Mediterranean climate areas, i.e. areas with wet, mild winter and dry, hot summers. With gusts of wind typical in those areas, bushfires spread very fast and often wipe out large areas of vegetation, decimating whatever happens to lie across their path. For example, just before Christmas, one of my field sites was completely wiped out.

BBC News item on mountain fire above Cape Town, South Africa Copyrighted  image Icon Copyright: BBC News BBC News reports on the Cape Town fire

But is there a silver lining to bushfire?

Well, bushfire is a key part of such ecosystems, providing a natural and beneficial disturbance on vegetation structure and composition. For example, it removes the slow growing but dominant trees and shrubs, thereby opening up space for other species (e.g. herbaceous, grass-like) to come. Fire is also important in returning back nutrients to the soil, i.e. those nutrients that were previously locked up in plant biomass.

In fynbos, i.e. a typical type of the vegetation prevalent in the Cape Floristic Region, fire happens in cycles of 10 - 50 years. Often nature reserve managers try to keep this cycle, by fighting any fire that happens early or conducting a controlled burn if fire is late in coming.

What causes fire?

Often fires are likely to start, during the summer season, which in the Cape floristic Region falls during November – April. The ignition cause could be heat waves, lightning, focusing of solar rays through broken glass or in some cases human negligence. But once the fire gets started; often wind is responsible for fanning and spreading the fire.

The fire that happens could be of different magnitude and intensity; dependent on the type and age of vegetation (fuel) e.g. certain species burn at a higher temperature and keep the fire on, while old vegetation is often prone to burn quickly. Also the prevailing weather conditions e.g. humidity or precipitation exert some control.

How does life survive fire?

Animals, particularly birds and mammals are well adapted to outrun fire. However being stationary, plants require a different sort of solution. Some plants called ‘resprouters’, tolerate some extent of fire damage and use their bulbs or roots to resprout back after the fire. Other plants called ‘reseeders’ employ a strategy of rapid germination after fire to colonize the newly opened up space. The seeds of such plants often lie dormant and are woken up through the heat from the fire or the ‘smell’ of smoke.

Post fire regeneration at Steenbras, Western Cape Copyrighted  image Icon Copyright: Deryck DeWitt Post-fire regeneration at Steenbras, Western Cape Deryck De Witt
 

What do nature reserve managers do?

The strategy of nature reserve managers involves, making visitors and local populace aware of the fire hazard, as well as detection and suppression of fire when it happens.

Often information on prevailing weather conditions and vegetation age is used to calculate a fire hazard index for each day during the fire season to help ready reserve managers for any eventualities. Reserve managers are also often equipped with mobile fire fighting equipment to fight small fires. If the fire is not manageable, they can radio for regional assistance which might include air support. They are also supported by both institutional (e.g. Working on Fire) and volunteer services (e.g. Volunteer Wildfire Services).

During the low fire risk season (winter), nature reserve mangers are often busy making and maintaining fire breaks (which are vegetation free paths created to break the passage of potential of fire) as well as training their staff in fire fighting skills.

Finally, what am I going to do about my burnt site?

Well, I am going to take advantage of this unpredicted event to set-up an experiment to test how soil water regime controls seedling establishment and vegetation structure after fire. As the proverb says if life hands you a lemon, make lemonade out of it!

Find out more

Open University fynbos Research is funded by Darwin Initiative programme of the Department for Environment, Food and Rural Affairs of the UK government.

If you are keen to study, the often complicated and fascinating relationship between living things and their environment; you may wish to consider the level one Introducing Environment (Y161) course; or the more advanced Environmental Science (S216) or Ecosystems (S396).

 

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