School of Agriculture and Fisheries Sciences

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Browsing School of Agriculture and Fisheries Sciences by Subject "Agrobiodiversity Namibia"

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    Comparison of the rehabilitative effects of mechanical and chemical methods of bush control on degraded highland savanna rangelands in Namibia
    (2010) Kahumba, Absalom; ;
    The study was carried out at Spes Bona 207 farm in Hochfeld district, and Neudamm 63 farm in the Khomas Hochland district,Highland savanna in Namibia. The objective of this study was to investigate the rehabilitative effects of mechanical and chemical methods of bush control of an invasive bush species Acacia mellifera for achieving long term rehabilitation of a degraded highland savanna rangelands in Namibia. At farm Spes Bona, three belt transects (50 x 5m2) were laid in chemical treatments and another three belt transects (50 x 5m2) were laid in mechanical treatments. Moreover, the same method was used in the control experiment. At Neudamm farm, a 200 x 100m2 plot with 495 Acacia mellifera treated stumps were divided into 3 sub-plots for each treatment (mechanical, chemical and control). Each sub-plot was further divided into 3 replicates. In each replicate, stumps were randomly assigned key-tags with sequential numbers from 1-55 per sub-plot, for assessment purpose. At Spes Bona farm, the grass tuft density of species Aristida congesta, Cenchrus ciliaris, Chloris vigata, Eragrostis rigidior, Eragrostis viscosa, Melinis repens and Melinis villosum was significantly higher (P0.05) in chemical and mechanical than in control treatment. Similarly, the total grass density had greater values (P0.05) high in chemical (36.1 ± 9.6a), and mechanical (31.7 ± 9.7a) than in control (25.7±9.0b) treatment. The soil condition did not show significant difference (P0.05) between treatments. Total density of woody plants was significantly greater (P0.05) in the control than chemical and mechanical treatments. At Neudamm farm exmortality of stumps was significantly higher (P0.001) in chemical than in mechanical and control treatments. On the contrary, coppicing of stumps was significantly lower (P0.001) in the chemical method than in the control and mechanical treatments. Tuft greater values outside the canopy than underneath the canopy