The Cichlid Fishes of Lake Malawi, Africa

Abstract of Doctoral Dissertation

Francis Xavier Mkanda
University of Manitoba, Winnipeg, 2001
Adviser: David G. Barber  

Farmers' survival strategies and soil erosion in the Lake Malawi/Niassa/Nyasa Basin - in the context of biodiversity conservation in the lake; the case of Linthipe River catchment.  

This dissertation provides an understanding as to why soil losses on Agricultural land in the Lake Malawi/Niassa/Nyasa Basin are excessive notwithstanding the various soil-conservation methods that the Government of Malawi prescribes. These soil losses result in a decline of soil fertility and crop yields thereby reducing the nation's self-sufficiency in food supply. Additionally, high rates of sediments are being discharged into the Lake where they are potentially detrimental to its socio-economic importance and ecological integrity. To provide the necessary understanding, the study assesses the distribution of soil-erosion risk in the Linthipe River Catchment in relation to physical and socio-economic factors. The Linthipe is used as a case study because it is a large catchment (about 8640 km2) with a high human-population pressure, steep gradient, high rainfall, and poor vegetative cover thereby providing an ideal opportunity for examining what happens to a large catchment when it is intensively developed for agriculture and human settlement. Distribution of erosion risk is assessed using the modified SLEMSA model, while field data, measured from erosion plots, are used to validate the predicted soil losses. Socio-economic data reveal that farmers are aware of erosion degree and its impacts on their land. Therefore, the occurrence of high rates of erosion is not due to ignorance; a fact clearly supported by farmers' use of different soil-conservation methods in the study area. Rather, it is factors such as farm characteristics, and deficiency in inputs, namely labour, fertilisers, and low returns in the forms of crop yields and farm income, that force farmers to adopt survival strategies that lead to ineffective implementation of the recommended soil-conservation practices. Consequent upon these survival strategies, excessive erosion occurs in the catchment, and high rates of sediment are discharged into Lake Malawi, where they have ramifications for biodiversity conservation. The study, therefore, concludes that both agricultural productivity and Lake Malawi's biodiversity are under continued threat unless measures are taken to ameliorate the socio-economic constraints. To safeguard against further soil loss and its consequences, it would be appropriate for the Malawi Government to prescribe recommendations that will, hopefully, not only sustain agricultural productivity, but also conserve the Lake's biodiversity. These recommendations include retaining natural vegetation, improving cover on agricultural land, and restoring cover on cultivated land of marginal quality. [Abbreviated abstract]




free hit counters