The effects of indigenous cultivation practices on the recovery of dry miombo woodlands in Central Zambia
MetadataShow full item record
Miombo is the most dominant vegetation type in Zambia and covers 53% of the country. It is dominated by species of Brachystegia, Julbernadia and Isoberlinia. In the study area, pockets of other vegetation types like the munga may be found within Hie miombo, especially along drainage lines. Munga is an open decidous vegetation with scattered or grouped emergents dominated by species of Acacia, Combretan and Terminalia. The woodlands are used for agriculture, woodfuel production and timber harvesting. Expansion of agriculture, especially crop cultivation, is degrading miombo woodlands through forest clearing and land tillage. Under such conditions, it is not known whether miombo regenerates. In other ways, is the recovery of miombo woodlands negatively affected by cultivation and other land uses? Due to population growth in the vicinity of Lusaka city, more land is being cleared for cultivation. With increasing intensity and extensity of vegetation cover clearing, is the vegetation disappearing or regenerating after abandonment? The rationale of the study was to assess how miombo woodland responds to clearing for cultivation. The broad aim of the study on the effects of indigenous cultivation practices on the recovery of dry miombo woodland in Central Zambia was to investigate semi-permanent cultivation practices and how this landuse affects the miombo woodland and its recovery. The specific objectives were to: describe the structure of relatively undisturbed woodland stands adjacent to cultivators' plots; describe the pattern of forest clearing and land tillage practices on cultivators' plots; describe the pattern of forest regeneration on current and abandoned cultivators' plots and; assess soil organic matter in current and abandoned cultivators' plots and adjacent relatively undisturbed woodland stands. The research hypotheses were that (1) forest clearing for agriculture and subsequent crop cultivation reduce species diversity and forest recovery in dry miombo woodland and (2) crop cultivation negatively affects soil organic matter content and the rate of recovery by abandonment. The study was done using three different methods: farmer interviews; woody plant inventories; and soil analysis. Data were computerised using Excel spreadsheets and analysed by PC-ORD and SYSTAT Programs. The average tree density in mature woodland plots was 1362 stems per hectare while mean height was 11 metres. Seedling/sapling density in mature woodland was 48 250 stems per hectare. The principal dominants among canopy species were Brachystegia spiciformis and Julbemadia globiflora. The tree density in the fallow plots increased with age of fallow. Seedling density was lowest in cultivated plots and highest in mature miombo. The pattern of evenness and diversity was not readily discernible and could not be linked to age and land use type. The classification of plots using cluster analysis also revealed that occurrence of characteristic species is not associated with age or status of plot. In addition, there was no evidence that woodland recovery was impaired by cultivation. Similarly, soil organic matter content was not related to vegetation type, age and status of plot. The hypotheses that clearing for agriculture and subsequent cultivation reduces species diversity and forest recovery in dry miombo is not supported by the findings of this study. The hypothesis that crop cultivation negatively affects soil organic matter content and the rate of recovery following abandonment is also not supported by the findings of this study. These findings indicate that present day semi-permanent cultivation can be practiced in dry miombo on a sustainable basis without negative impacts on the miombo ecosystem.
- Natural Sciences