Ecological role of Fire

The general idea is that fire is bad and it must be stopped at all costs.
However and this is a big HOWEVER. Fire is one of the most important management tools when working with a conservation management plan.

Why?
Let me explain the ecological role of fire:

Because of thousands of years worth of natural fires-caused by things such as thunderstorms-the plant life in South Africa has evolved in such a way that a great many of them now actually need fire in order to survive. In this way fire plays a large role in the revitalization and renewal of the environment. This means that the plants actually need the fire to do things like germinate, and to reduce moribund (excess dead grass collecting on the ground and around the grass stems causing severe reduction in the amount of palatable grass).
Due to human habitation, Elephants- the bulldozers- are no longer able to keep the amount of tree and bush encroachment in check. This means that alien invasive and even indigenous plants are growing like there is no tomorrow and in effect encroaching. An effective way to manage this is by burning.
A lack of burning over the years has had a large impact on the ecosystems.

Fire has different effects on different ecosystems. The general effect however is that it effects the progress of plant succession. The reason for this is the different roles that plants play in the progress of succession. For e.g. here on Sondela we have a large section (+/- 400 hectares) that burnt in September 2010. everything about the fire was ecologically perfect. It reduced moribund. It burnt over a section of vlei where we had problems with bull rush encroachment (see blog about Bulrushes) reducing the bull rush quite a bit. The burnt grass was able to put nutrients back in the soil due to rain several days later and very still windless days in between.
This in turn meant that less competitive grass with a higher nutritional value (Cenchrus cilliaris-fox tail buffalo grass; Digitaria errantha-common finger grass; and Panicum maximum-guinea grass) get the chance to grow.

On another level this caused the veld that was previously in a bad condition to degenerate even more. Causing competitive, nearly unpalatable grasses such as; Hetripogon contortis-spear grass; Hyperthelia dissoluta-yellow thatch grass; and Hyperrhenia filipendula-fine thatch grass to grow in excess.
Let me explain:

As the new sweet and very nutritious grass grew, all the grazers-both bulk(e.g. Zebra) and selective(e.g. Red Hartebees)-moved to the recently burn area to feed (at that point there was not much fresh green grass elsewhere, as is the case in winter). They grazed in there to the point where the new high quality grass could now grow fast enough to keep up. This caused them to simply stop growing, giving the low quality grass a chance to over take the area.


{Random explanation: When considering the important role that grasses play in the succession of veld, we need to remember where individual grass species fit in.

Grasses with a low grazing value:
Heteropogon contortus
It is what we call a perennial tufted grass- this means that it grows for more than five seasons (rain seasons, so if an area has more than one rain season in a year it will not grow for such a long period of time: in the bush veld they grow for +/- five years)
It grows in disturbed areas for e.g. over grazed areas, and tends to grow so dense that other vegetation struggles to grow.
Hyperthelia dissoluta
As with the spear grass it is a perennial grass, and prefers disturbed areas.
Hyperrhenia filipendula
Also a perennial grass that grows in disturbed areas.

Grasses with a high grazing value:
Cenchrus cilliaris
It is a perennial grass. It is also what we refer to as a decrease which means that in over grazed areas it decreases. This is the same with Digitaria errantha as well as Panicum maximum.