Effect of land degradation on the above-ground vegetation and soil seed bank of a Rangeland in Kunene region Namibia
Land degradation is a global threat to ecological, economic, and social sustainability, particularly in semi-arid and arid regions such as Namibia. Degradation is affecting above ground vegetation and seed bank composition, hindering their recovery. To address this issue, it is crucial to assess land conditions at different levels and develop effective strategies for restoring degraded rangeland. The understanding of how land degradation impacts the seed bank composition could provide insights into the potential for natural regeneration and the need for active restoration efforts. This study assessed and compared the characteristics of the aboveground vegetation and soil seed bank at sites of varying degrees of degradation in the Kunene Region of Namibia. A total of three sites were identified per level of degradation. At each site, two belt transects were set up, and five quadrats were sampled along each transect. Woody plant species were identified and counted in a 20 x 20 m quadrat, while herbaceous plants were assessed in a 1 m2 quadrant, nested within the larger quadrat. Soil cores samplers measuring 9.7 cm in diameter and 5 cm in depth were obtained using a soil drill at the centre of the 20 x 20 m quadrat. The species diversity, richness, density, and regeneration of the above-ground vegetation showed an ascending pattern along the degradation gradient from high to low. The dominant species in moderate and low degradation sites was Catophractes alexandri, while Pechuel-Loeschea leubnitziae was the dominant species in high degradation sites. Seed bank species diversity and density increased along the degradation gradient from low to high. Though the high degradation sites recorded the highest density and diversity of seed banks, most of these plants were annual herbaceous species, including alien invasive species, namely Datura stramonium. Perennial grasses, with high fodder value, were replaced by annual species in soil seed banks due to degradation. Perennial species dominated low- and moderate-degradation sites. In the seed bank, a few woody species were found at low and moderate degradation sites, while no woody species were found at high degradation sites. The findings emphasise the current and future challenges to the study region and that restoring woody vegetation from soil seed banks has limited potential, hence highlighting and recommending the need for further research
Above-ground vegetation, Degradation sites, Kunene region, Land degradation, Species composition, Soil seed banks, Namibia, University of Namibia
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