Before the turn of the century man and animals lived in harmony within the KS teak forests. The human population was low and did not cause serious destruction and degradation of the forests and forest resources (Judge, 1986). Fire played an important role in the shaping of the forests. Natural fires were less frequent compared to man-made fires of recent times. As long ago as 1909 the mine and railway sectors realised that the KS teak forests had some of the finest indigenous hardwood timbers of the Baikiaea plurijuga, Pterocarpus angolensis and Guibourtia coleosperma species. These species were over-exploited for railway sleepers and flooring material.
The ecology of the KS teak forests can be interpreted as one of a plant community whose climax status is forest but which has been reduced to woodland or secondary forest by burning, over-exploitation for commercial and subsistence purposes, browsing and grazing activities. Currently the plant community is in a dynamic state in which the structure and composition change under the interplay between rainfall, temperature, fire, domestic stock, wildlife and anthropogenic influences.
Human population pressures have probably caused more fundamental changes to vegetation composition, structure and functioning. Encroachment and clearing forest for agricultural purposes has had a marked impact on the forests. What is lamentable is that the agricultural potential of the Kalahari sand is low and crop production levels minimal. Wildlife production and extensive grazing by cattle are probably the optimum agricultural policy rather than crop production. Due to the disturbances mentioned above, characteristics of secondary forest types are becoming more apparent in most forest reserves.
There are many factors limiting the recovery of these forests. Fruiting of most of the woody species is erratic and hence natural regeneration from seed is poor. A high proportion of germinating seeds and seedlings are consumed by rodents and domestic and wild animals. A dense under storey of thicket shrubs that greatly suppresses or completely prevents the growth of young trees is becoming increasingly predominant. Harvesting and grazing pressure is increasing as human and livestock populations continue to increase. The successional secondary forest is extremely sensitive to damage and destruction by late dry season fires.
Attempts at artificial regeneration of the forests has some potential but has so far met with mixed success. Specialised nursery and planting techniques need to be improved. So is the need to effectively control the competing vegetation of grasses and thicket shrubs to assist natural and artificial regeneration. Seedlings and saplings regularly suffer severe dieback, leading to stunting and bad form, caused by frost that occurs nearly every year in some areas.
The KS teak forests of western Zimbabwe have been progressively reduced over the years as a result of human disturbances. Human activities have long been recognised as a major influence on vegetation (Judge, 1975; Calvert, 1986; Wood, 1986). By harvesting plants for commercial and subsistence purposes, or clearing forests for agriculture and causing wild fires, man has directly altered the natural vegetation of the KS teak forests. The disturbances are such that once the vegetation is altered the climax vegetation is slow to return or may never return at all.
