Desertification through irresponsible burning.

(Pseudonym: Amani. M. Chungaji) Guardian Tz Sept 2006

Man is thought to have started to use fire to cook with 1.5 million years ago from evidence found in South Africa. Our early ancestors may have been burning there environment, or spreading existing fires long before that. It can not be disputed that man has effected his environment for a very long time, mainly by the use of fire. This man made environment is beneficial to man, but is burning an environmentally sound action for the long term? The debate rages on.

In the mean time here in Tanzania we burn most of our bush and wild pasture every year. It is customary to do so, but is it truly wise. What has scientific study taught us?

Reasons of burning:

· Stimulate new growth with fresh palatable green grass for cattle and wild grazers.
· Reduce internal and external parasites of livestock such as ticks and worms.
· Remove old dead woody grass increasing visibility.
· Clear thick bush and undergrowth increasing the grassland available to grazers.
· Ash from the fire is a short term fertilizer.
· Prevention of larger fires late in the season.

Disadvantages of frequent burning:

· Soil exposed to sun:-

Initially the black color of a burnt area increases the soil temperature substantially. Sunlight burns of organic matter in top layer of soil reducing nutrients needed by plants and creatures (bacteria, nematodes, worms and so on) many of which enrich the soil. Generally the less organic matter in the soil, the less moisture that the soil is able to retain. If the water moves through the soil that can no longer retain it, it will carry off valuable nutrients, a process called leaching of nutrients from the soil.

Sunlight bakes the top layer of soil causing a hard surface the germinating seeds and small creatures find hard to penetrate. This has been shown to reduce plant densities and therefore ground cover.

· Increased sheet and gully soil erosion due to reduced ground cover. Sheet erosion is the result of rain drop impact and this movement of large sheets of soil during heavy rain generally goes un-noticed.

· Research seams to indicate that the most desirable grass species for wild and particularly domestic grazers do not respond well to frequent burning but they are not affected by an occasional burn every four to five years.

· Less cover for animals to hide in, exposing them to predators and scorching sunlight.

I have looked in several books including “Ecology and Field Biology” (Robert Leo Smith), “Managing Protected Areas in the Tropics” (IUCN/UNEP) and many more, but I could not really find anything to encourage us to burn. Almost all of the result of regular burning listed where negative in the short, and especially in the long term.

And yet as we have burnt for ever, and the custom is strong, it is very hard to persuade traditional societies to burn less. It appears to be traditional to blame a bush fire on “anybody but me” as who knows where it may end up if the wind changes. Fires generally are set secretly except where government is involved.

During the dry season, the dry grass that is so often burnt is after all the standing hay that sustains the wild and domestic grazers. Generally they will not thrive and multiply eating it; however it can sustain them until the next rains. This standing hay is a natural fodder bank, if it is burnt off and the rains are late or fail entirely, the grazers will starve.

Logically we should burn after the first rains of the season to ensure immediate re-growth, if we are to burn at all. The experts all recommend burning on a windless late afternoon after the first good rain of the season as the resulting fire will be “cooler” doing less damage to the plants and soil. Under these conditions most fires will burn out in the cool damp night air and not “runaway”.

Some of the worst fires are lit by hunters, poachers and honey gatherers, all of whom gain from burning at the worst time, at the beginning of the dry season. All of those responsible should think about the longer term. The burning will go on always, but it should be done with some forethought. Frequent burning at the wrong time, all agree, will drastically damage the environment. Combined as it is in many areas, with overgrazing, this will cause serious irreversible damage to the environment and reverse the natural succession, resulting in permanent desertification.

Please think before you burn!