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VELD FIRES

 

By Dave Rushworth 

 

Yes, this is the 'mad' season for intentional and uncontrolled fires all over our area.  Some are started for a reason and others are caused by carelessness or vandalism.  Whatever the reason for burning, tremendous damage is being done to our veld by wrong burning. By law, all persons require a permit to burn veld before a certain date and are regulated in the way they may use such areas after a burn.  These laws are intended to restrict burns to a suitable period and to permit healthy regrowth afterwards. Ideally, burning should only be carried out on damp soils to minimise the effect of heat on the soil. Natural fires normally only occur during a lightning storm, where there is sufficient combustible material and where the fire has a chance of being doused by rain within a short space of time.  Man made fire has been around for a long time and it's abuse is widespread.

 

The last discussion on Soil mentioned the living or biotic factors of soil - the macro and micro-organisms, in their millions, that live and work in the soil.  These 'insects' and bacteria all require oxygen through well aerated soil and moisture through porous soil. The lack of either oxygen or moisture will result in the depletion of soil organisms. These organisms are also very vulnerable to excess heat which will kill them off.  Excess heat actually sterilises the soil of all biotic factors and ANY FIRE THAT BURNS THE SOIL IS A 'BAD' OR DAMAGING FIRE.

 

If grasses grow very densely and remain ungrazed they can develop a thick 'hamper' of old grass that shades out and retards any new growth. If this persists for a long period it can kill out some of the best grasses. The ideal is to mow or graze the area and thus remove the 'top hamper' and incorporate it into the top layer of soil. This treatment provides organic matter for soil organisms, prevents erosion and helps retain soil moisture.  If this treatment is not possible then many folk resort to the use of fire.  Burning is a dangerous alternative if conducted without a prior, informed assessment of the area to be affected.

 

HOT FIRES burn INTO THE WIND and travel across the land relatively SLOWLY inflicting great heat on the soil.  COLD FIRES burn WITH THE WIND and travel across the land at a high speed, thus avoiding any lengthy heating of the soil.  Rather like passing your hand through a flame without getting burned, compared to holding your hand in a flame for a while.

 

The intention of 'COLD BURNING' is to quickly remove the 'moribund' top hamper of grass. Because 'cold' fire travel with the wind they are normally characterised by high flames, which can also remove new leaf growth on trees, birds nests, insects, chameleons and other valuable parts of the environment.  THINK FIRST !   It is still much better to run a herd of cattle (or buffalo !) through the area or in some way combine the dead matter into the soil.  Fires destroy 'food matter' and produce only gasses and carbon particles. Our chameleons (as one example) are being brought to extinction by veld fires. They can't escape upwards fast enough to avoid the heat of high flames.  Large mammals have been noted running back through the flames of a cold fire to seek safety behind the fire.  This is a tactic that could be used by humans in a threatening situation, who would probably be only slightly singed by the experience. Fires not only burn matter but also use up oxygen and there is a real danger of suffocation if surrounded by fire for too long.  Anyway think before starting a cold fire.

 

HOT BURNS are used as a method to destroy 'woody vegetation' in areas that are 'perceived' to be 'bush encroached'. Hot burns are characterised by low flame, which may look harmless but they produce high ground heat. This method of burning is the most abused destroyer of our veld - even worse than 'overgrazing' !  The object is to kill all woody stems by subjecting them to great heat.  The effect of 'high surface temperatures', which kill not only soil organisms but also small mammals and slow moving reptiles, such as tortoises, is normally ignored in favour of a 'cosmetic effect'.  I say 'cosmetic effect' because it is trying to cover up rather than address the root problem. Most mature trees bear fire scars at the base of the trunks where fires have developed a 'hot patch' on the down wind side. Such consistent burning eventually kills the large trees as well, with associated ripple effects.

 

Depending on the soil type, most of our 'bush encroached areas' are a natural reaction to the 'root cause' of 'overgrazing' or abuse.  If you damage your skin you develop a 'scab' to protect the area,.  If you keep scratching the scab you will often end up with a permanent scar.  In abused (overgrazed or over-burnt) areas the protective 'scrub' develops to prevent further abuse.  In most cases the 'pod bearing' plant species involved have thorns or spines and are 'nitrogen producers', which help 'fertilise' and protect depleted soils.  Humans protect and shade their vegetable gardens - so why not 'nature' ? 

 

It takes time to 'heal' an overused area and by burning out 'bush encroachment' one is 'scratching the scab' and opening up the old wound.  To try and duplicate what 'nature' intended, after clearing, one would have the great expense of restricting grazing, shading the soil and mechanical fertilisation of the area. There are occasions where we humans don't have the time to wait and will use hot burns. In these cases we must be prepared to bear the costs of our actions that 'nature' would have done for free.

 

Unless there is sufficient 'combustible material' the fire will not be hot enough to kill the plant by simply burning off surface stems. The result will be that the plant will 'fight back' by producing double the number of stems - or 'coppice growth' - which will increase the 'bush encroachment'. Most of our area bear witness to bad burning policies through the evidence of coppice growth.

 

If the hot fire is successful in killing off the root stock it will also have completely sterilised the soil, leaving the whole area dead and barren, apart from a few hardy, pioneer 'weeds' to start the long rehabilitation process. We could just as well have used an atomic bomb to do the job for us.  Why do many of us persist in trying to produce deserts when we know the implications ?

 

Our fragile, natural systems can't cope with human greed and impatience. We need to appreciate rather than destroy the blessings around us. If we are not sure about burning the best motto is -" IF IN DOUBT - LEAVE IT OUT !!"