The effect of human activities on the dry savanna woodlands
In the description of the ecology of the dry savanna woodlands of Namibia,
the effect of human activity should not be neglected. In view of
the subdivision of the woodland vegetation into herbaceous and woody components,
human impact is considered separately for each of the two.
Human impact on herbaceous vegetation
The use of fire
Although some fire occurs from natural causes, most fires today are as
a result of the activities of man (Siegfried
1981). The indigenous people of Namibia have been using fire for
centuries, for a variety of purposes. Vedder
(1928 p. 43) describes the use of fire by the Herero as a range management
Fire has also been used as an aid to hunting. The early growth
of grass that is stimulated by fire in the dry season has been used to
attract game animals to specific areas (Vedder
1923, Vedder 1928, p. 43, Lusepani
al 1998, Anon 1999), making
them easier to find and hunt.
The removal of undergrowth results in greater long distance visibility
and facilitates the detection of game animals (Tuomasjukka
al. 1998), and easier tracking (Lusepani
al 1998, Büschel 1999).
In recent years the greater visibility is also said to have served poachers
to detect the movement of law enforcement officers.
The greater visibility at ground level also facilitates easy detection
and collection of veld foods such as the mangetti nuts (Tuomasjukka
The effect of fire in the past and today should be compared in terms
of the frequency and season of burning. Goldammer
(1998) highlights the decline in nomadic habits of the indigenous people
in this regard. This, together with the growing population of Namibia,
is likely to have caused an increased incidence of fire on the woodland
areas of the country.
Grazing by domestic animals has significant effects on the development
of the herbaceous vegetation. Heavy grazing pressure may reduce the competitiveness
of the grasses, while light grazing may stimulate the development of the
grass layer. Apart from such direct influences, grazing may significantly
effect the development of the fuel load.
Harvesting of grass
The harvesting of grass for thatch has only been recently considered by
the forestry authorities, although the practice seems to have been ongoing
Human impact on woody vegetation
The Namibia Forestry Strategic Plan (NFSP
1996) describes a variety of uses for wood products in Namibia. These
products range from building and fencing material to the production of
utensils and farm implements. While sawn timber may not have been
of significant importance in the past, the woodlands have been exploited
primarily for Pterocarpus angolensis and Baikiaea plurijuga.
Other important species are Terminalia sericea and Burkea
africana. The carving industry is now also significantly affecting
exploitation rates particularly of P. angolensis.
In order to affect some control over the harvesting and to ensure the
continuity of the individual species, minimum tree sizes have been specified
in the forest legislation (). However, since many of the P. angolensis
stands in the woodlands seem even aged (Groome
et al. 1957), this specification caused conditions similar to those
of a clearfelling in some regions.
An important overview of the use of woody resources is provided by Erkkilä
& Siiskonen (1992).
Fruit and seed collection
Fruit and seed are of significant socio-economic importance to many rural
communities. Woody species of particular value seem to be Schinziophyton
rautanenii, Berchemia discolor, Vangueria infausta, Gouibourtia
colesperma the Grewia species and Strychnos species.
The effect of seed collection on most species varies between regions, depending
on the proximity of the plants to human settlements.
It is known that entire families of the San communities will travel
long distances to S. rautanenii stands for fruit collection.
Observations in the Otjozondjupa region show that in some areas almost
the entire crop of is collected for food and the production of alcoholic