Masters Degrees (DES)

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Browsing Masters Degrees (DES) by Subject "Bush encroachment"

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    A cross sectional comparison of chemical treatment on plant biodiversity at Neudamm farm, Khomas region
    (University of Namibia, 2020) Shigwedha, Diina
    This study determined the impacts of chemical application on plant biodiversity in comparison to the control ecosystems over a three-year period at Neudamm farm in Khomas Region, Namibia. In this study, for herbaceous plant sampling, a total of 40 (1m2) quadrats were randomly laid in each of the three chemically treated sites (treated in 2015, 2016 and 2017) and in the control site to record the herbaceous plant density, plant species composition, dry matter production and ground cover. For woody plant sampling, a total of three 250 m2 belt transects were randomly laid in each of the three chemically treated sites and also in the control. All woody plants in the belt transects were identified, measured and recorded for plant height and canopy diameters. For soil sampling, a total of ten soil samples were collected from the three the belt transects in each of the three chemically treated sites and also in the control at a depth of 15 cm using a soil auger. The soil was analysed for pH, soil minerals, organic carbon and organic matter. A total of 20 grass species were identified in all the four sites, of which 55% were perennials and 45% were annuals. The mean total grass tuft density was significantly higher (P < 0.05) in control and the chemically treated sites of 2015 and 2017, but lower in the chemically treated site of 2016. Herbaceous biomass production was significantly higher (P < 0.05) in chemically treated site of 2015 (975 Kg DM ha-1), followed by 2016 (925 Kg DM ha-1) and least in the other two sites. The chemically treated site of 2016 had greater (P < 0.05) ground cover percentage than the other three treatment sites. The total woody plant density was significantly higher (P < 0.05) in the control (14 160 TE ha-1) than in all three similar chemically treated sites. The canopy cover percentage and woody plant densities in all woody height categories were higher (P < 0.05) in the control and the chemically treated site of 2017, than in the other two sites. The chemically treated site of 2015 had the highest amount of soil pH (6.06), followed by the control (5.61) and the chemical treatment site of 2017 (5.5), and they were statistically significant (P < 0.05). The organic carbon and organic matter percentages were significantly (P < 0.05) higher in the chemically treated site of 2015 than in all the other sites. The soil in the chemically treated site of 2016 had the highest Ca (551 ppm), K (197.3 ppm), Mg (76 ppm), P (23.3) contents, followed by the site of 2015 than in the control. This study concluded that chemical treatments have impacted on the plant biodiversity of the treated rangelands by improving the herbaceous plant species, biomass yields, reduced bush density and enhanced the soil chemical properties.
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    The effect of bush clearing on soil properties, at Cheetah conservation fund farm in Otjozondjupa region, Namibia
    (University of Namibia, 2018) Enkono, Angula Nahas
    The thesis discusses the problem of bush clearing as they affect soil quality, its productivity and environment in the semi-arid areas. In this case, land clearing came as a result of bush encroachment control mechanism. Bush encroachment is a form of land degradation present prominently in semi-arid areas. Namibia is affected by bush encroachment on a massive scale. The phenomenon is currently understood to affect large part of the country, causing severe economic losses for Namibia, in both the commercial and communal farming areas. The primary aim of the study was to investigate the effect of bush clearing on soil quality, particularly the soil macro-nutrients, N, P and K. The study was conducted on one farm, Cheetah Conservation Fund (CCF) on two experimental fields. Samples were taken from two differentiated (cleared and non-cleared area) ecosystems. Fifty (50) soil samples were collected at depths of up to 30 cm. In each field 25 samples was collected, the samples were collected at 200 metres interval. The soil was tested for selected macro-nutrients and micro-nutrients. Soil texture and composition was also tested as well as electrical conductivity, pH, and soil organic matter. The bush encroached site differed significantly from the cleared site with regards to nitrogen content, where high nitrogen content was recorded in the encroached site. The high occurrence of N content in the bush encroached site explain the nitrogen fixation by leguminous trees. Contrary to the study’s initial hypothesis, which hypothesized that there is no significant difference in SOM between bush-cleared and bush encroached sites, the study found that there is however a significant difference in the median SOM between the two sites.
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    Quantification and characterization of encroach bushes targeted for conversion into livestock feed at Neudamm farm, Khomas region, Namibia
    (University of Namibia, 2020) Shilume, Kaino Temapo
    Bush encroachment is a serious problem in Namibia leading to significant reduction in livestock production and biodiversity. Harvesting encroacher bushes for conversion into livestock feed is a practice becoming more common. Every encroached area is unique in species composition and density of encroacher bushes and hence characterisation of such bushes is essential prior to laying out harvesting strategies. The main aim of this study was to determine the species composition and estimate the amount of feed-suitable biomass of the dominant species constituting encroacher bushes in Block G of Neudamm Farm. Landsat images (Landsat 5 TM and Landsat 8 TM) of the study site were used to stratify the area into low, medium and high bush density classes to assess how encroachment changed between 1989, 2000 and 2017. In the high bush density areas, bush densities, species composition, diversity and similarity were analysed in relation to site, topographical positions and soil properties. Data were gathered from 27 sample plots (2 x 50 m). There was a 14% increase in area covered by high bush density between 1989 and 2017. Senegalia mellifera had the highest density and biomass across all sites and at all topographical positions. Bush density differed significantly only between sites. Site 2 had significantly higher bush density than Sites 1 and Site 3. This higher bush density in Site 2 was contributed by presence of high numbers (in excess of 10000 plants/ha) of small sized trees and shrubs. Only Sodium had a negative correlation (Pearson correlation) with bush density at different topographical positions (p=0.3888), this could be because Na increases osmotic tension, by which water is held in the soil and as result the plant die-off. The total biomass of bushes varied significantly across sites (Kruscal Wallis Test, P=0.024 and biomass fit for animal feed varied significantly across Sites Kruscal Wallis Test, P=0.027). This variation is linked to variation in bush density since Site 2 which had the highest bush density also had the highest biomass. It is concluded that 4.8 tonnes/ha can be harvested by selectively removing S. mellifera. The study recommends harvesting of only S. mellifera as this would yield large amounts of uniform feed and preserve other rare species especially those being given special protection like Boscia albitrunca, Searsia lancea and Ziziphus mucronata. Similar studies are recommended for other areas where encroacher bushes are to be harvested.