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Fire, Smoke and Fynbos

Going.Local
Published on March 8th 2021
2
Protea fire fynbos
Large fires and firestorms are on everyone's mind when summer rolls around. The billowing smog and cataclysmic devastation they can cause is something that most fear. The recent fires of 2019-2020 ravaging Australia (covering 85 000 km2 and affecting 3 billion animals) and California (4050 km2 in 7 days) paint a dismal picture.
So how did South African fynbos adapt to wildfires? Why is the frequency of fires important? We take a look at the strides South African researchers have made in studying this relationship and how you can apply some easy steps at home to grow your own natural fynbos garden.
Palmiet riet burnt fire fynbos
The Overberg region has seen multiple fires within the last 10 years. A region with a high number of red data list species.

History of Fire in Fynbos

In 1985 three researchers from the Jonkershoek Forestry Research Centre noted: “ No data on fire behaviour in fynbos are presently available.” (1). So what have we managed to learn in the last 35 years?
Here are a few Tidbits:
  • Fire outbreaks (frequency) historically occur every 7-55 years, with most protected areas burning every 10-20 years (2-3).
  • Natural sources of ignition include lightning (only a fraction of strikes can ignite fires) and tremors or falling rocks (2).
  • Fynbos fires are as intense as Californian chaparral but less flammable.
  • Keurtjiebome (Virgillia spp.) strips act as firebreaks between older Afrotemperate forest and fynbos shrubland.

Blossom Tree

Virgilia spp.

  • Fire may play a role in disease and pest management.
  • Climate change models estimate that the Cape Floristic Region will be drier and hotter, which will mean larger/more frequent fires.
One study found that a five-year period between fires had a near-zero recruitment level (4), in other words, the period was not long enough to replace the original fynbos post-fire. As populations increase, the likelihood of more fires will necessitate an active role in conserving vulnerable areas.
This is but a small selection of the finds. To find out more, see the bibliography section for additional reading.
Protea seed heads
Some Protea can hang onto fruiting bodies or 'old flowerheads' until a fire comes along and stimulates the release of seeds.

Types of Fire Reliant Fynbos

There are several categories that fynbos can fall into in terms of reliance on fires. Some will try and resprout if the root system is not damaged, others will release seeds, while some seeds will only germinate after a fire.
Obligate reseeders Type 1
They survive fires by seed only. The fruits/old flowers (infructescence) will stay on the plant for multiple seasons. This means the mother plants die in the fire and the seeds need to germinate for the species to survive. The seeds cannot be stored for prolonged periods after exposure.
Examples:
Obligate reseeders Type 2
Ants and termites bury these seeds underground. The fire stimulates the seed to germinate. (+/- 1300 species, Mimetes, Restio, Proteaceae etc.)
Facultative resprouter
They can regrow from the root/stem after a burn and reproduce with seed.
Examples:
Obligate vegetative resprouters
They can only resprout, with no new seedlings from seed. Examples include Acrolophia capensis and Elegia juncea.
Protea resprouting
This is an example of a resprouter. Resprouting can occur if the root system is not irreversibly damaged.
If you think about this carefully, you will realise that all of these will need a good recovery time after a fire. Growing a fully mature Protea from seed takes a considerable amount of time. If two fires ravage an area in a short amount of time, it may decimate an entire species.

Fire rehabilitation

Burning fires can be unpleasant and cause severe allergies, aggravate asthma and lower visibility, but they are a necessity. Unfortunately, fynbos fires need to be within a given temperature range to be effective. Too hot and it will destroy rather than rejuvenate some species. Too cold and alien species will recover quickly and reproduce more effectively.
Did you know? Several researchers have been using fire to rehabilitate Tokai forest (one of the oldest plantations in SA).
A comprehensive program in Tokai has shown how a 100-year-old plantation can make way for its original critically endangered Cape Flats Fynbos.
Pincushion burnt fire fynbos
Some seeds require heat while others require smoke treatment to germinate.

How to germinate fynbos seeds

So you love fynbos and thought: " Why not sow some seeds in the garden so they can establish and grow by themselves?" It would be like creating a fynbos version of a meadow. Your number one hurdle will be to get these smoke and heat-loving seeds to germinate without a fire.
Did you know? Many fynbos species require a smoke treatment to germinate.
The easiest way, by far, is to buy smoke treatment discs from Kirstenbosch Garden Garden Centre. These can be popped in water along with your seeds for a nice soak before you sow them. It is an alternative to using smoke from smouldering fynbos (blown into an enclosure with the seeds for 24 hours). Undeniably the latter poses several fire hazards. Always make sure to follow legal and safety precautions.
Example of seeds that require heat for germination:
Example of smoke-stimulated germination:
Almost all fynbos!
Bulbs and fire
Fires are a way to reintroduce nutrients in areas with low bacterial remineralisation.

A Flower in a Fire

Some species only flower directly after a fire and will subsequently disappear. These are treasures to be observed in awe. The reason for this is most likely the nutrient deposits that follow a large fire.
Some species of note:
You might be surprised to note that several orchids fall into this list including, Disa bivalvata, Disa tenuifolia and Disa racemosa. Although some may only flower for the 1st season following a fire, others will flower for several seasons.
*Disclaimer* Note that areas are highly unstable during and post-fire. One should not enter unless the area has been deemed safe by the appropriate authorities.

Have you started a new Fynbos Garden? Tell us in the comments below!

restio and fire
Bibliography:
(1) Van Wilgen, B. W., Le Maitre, D. C., & Kruger, F. J. (1985). Fire behaviour in South African fynbos (macchia) vegetation and predictions from Rothermel's fire model. Journal of Applied Ecology, 207-216.
(2) Allsopp, N., Colville, J. F., Verboom, G. A., & Cowling, R. M. (Eds.). (2014). Fynbos: ecology, evolution, and conservation of a megadiverse region. Oxford University Press, USA.
(3) Pooley, S. (2014). Fire on the Cape Peninsula, 1900–2000. In Burning Table Mountain (pp. 197-229). Palgrave Macmillan, London.
(4) Kraaij, T., Cowling, R. M., van Wilgen, B. W., & Schutte‐Vlok, A. (2013). Proteaceae juvenile periods and post‐fire recruitment as indicators of minimum fire return interval in eastern coastal fynbos. Applied Vegetation Science, 16(1), 84-94.
(5) Hitchcock, A., Cowell, C., & Rebelo, T. (2012). The lost fynbos of Tokai Park. Veld & Flora, 98(1), 30-33.

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