People are always very curious and horrified that in places
like Kruger National Park controlled burning takes place and want to know why
it is done. While in Skakuza, I contacted the Biodiversity Conservation Manager
/ Fire Protection Officer and this is their official release on the necessity
of burning. The opposite side of the road is always left unburned and the
difference can be seen in the last picture.
It does not take long for the animals to return to burnt
areas to enjoy the new shoots sprouting out.
What are bush (veld) fires about and how necessary are they
in the park?
African savannas have evolved with fire over thousands of
years and veld (or bush) fires are very common in these savannas, especially in
the dry season. Without fire, the vegetation and animal life of savannas would
consequently be very different to what it is.
In Kruger being a savannah system; the fire season generally
is between May and October, with most fires being set in July -September. Fires
in Kruger are managed according to the ‘patch mosaic’ fire policy. In brief,
the percentage of the Park which is burnt annually is dependent on the total
rainfall received during the preceding two years and the objective of fire
within the section. 
Research has also shown that the greater the rainfall, the
greater the grass production and the greater the area which consequently burns
every year. This relationship is consequently used to calculate an annual quota
of how much needs to be burnt. At the end of the summer season, firebreaks are
graded or burnt around the perimeter of the park and the infra-structure.
As soon as the grass is dry enough to burn, rangers apply
controlled burns in their sections early in the fire season when the grass is
still partly green thereby resulting in a patchy burn, i.e. some grass is not
burnt, or is poorly burnt, whilst in other areas, all grass is burnt. This
results in variable fire effects, which in turn have variable effects on a very
wide spectrum of organisms. Ignition is
usually at a single point, the idea being to imitate how nature does this i.e.
a lightening strike.
Another objective of this approach is to reduce the amount
of grass, thereby reducing the likelihood and extent of high-intensity fires
later in the season. The burns are monitored by means of satellite images
(MODIS– Moderate Resolution Imaging Spectro-radiometer) and information
provided by the rangers. Management burning normally stops at the end of July, when
the risks of a high-intensity fire, or an uncontrollable fire, increases
considerably. Later in the season (October to November) lightning fires may
occur.
Twice a day during the fire season, the rangers receive a
weather and ‘Fire Danger Index’ (FDI) reports via e-mail from the Fire
Protection Association’s Fire Protection Officer (FPO) in Skukuza. The FDI is
determined by using a number of weather criteria to calculate the risk or
likelihood of a fire running out of control. The index ranges from ‘Safe’ to
‘Extremely Dangerous’ conditions, when no fires may be lit, except for the
purposes of cooking. It is often cooking fires which result in runaway fires,
so please take care when making a braai fire!
Regardless of their cause, unscheduled fires occur every
year, especially from September onwards, when conditions are hot and very dry.
Most of these fires are ‘jump’ fires; fires which jump over the firebreaks
under strong wind conditions and result in high-intensity burns. Some of these
jump fires originate in Mozambique while others are caused by careless tourists
who throw burning cigarettes from their vehicles. Poachers sometimes burn the
veld intentionally to lure animals onto the resulting green lush, and people
walking through the park illegally from Mozambique and over-nighting in the
veld light fires which can spread the next day.
Contrary to what some people believe, veld fires very seldom
permanently destroy the vegetation in a savanna.
Perennial grasses which appear to have been destroyed completely
re-sprout from their basal parts the following season; while the annual grasses
survive fire by dropping their seeds early in the season, with fire having
practically no effect on them or the soil surface.
Woody plants, especially bushes, often get burnt down to
ground level (but are very seldom killed outright). They re-sprout again during
the next rainy season. Being taller, savanna trees also have thick bark for protection
and are little affected by fire, except perhaps to have their lower branches
scorched, during fire. But they are very seldom killed. Fire consequently has
the effect of keeping the veld more open, which in turn favours certain animal
species and is also beneficial to visitors as it provides greater visibility.
Is there impact of fires on animals?
Another misconception is that fire kills almost every animal
in its path. Remember that savanna animals have evolved with fire over
thousands of years and are therefore very successful in surviving fire.
Although some do get killed in fire, but by far the greatest majority survive a
fire. Animals can sense fire when it is still very far away and most normally
have enough time to escape or move out of the path of fire front.
Reptiles and many kinds of smaller mammals and insects escape
into holes in the ground or in logs, tree-trunks and under rocks, etc. where
they are safe, because the heat from the fire front seldom penetrates the soil below
5 cm in depth. These individuals consequently re-colonize a burnt area very
quickly after fire.
All fires are monitored by our rangers. After fire, rangers
will record co-ordinates and other information on the fire and send this to the
FPO. This information is used for a variety of management and research purposes.
Thank you Nick for this wonderful insight into burning.
.jpg)
.jpg)
