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1) to establish and optimise suitable protocols to study soil bacterial and fungal
communities, using both molecular and community-level physiological
profiling techniques in parallel. A dual approach of this kind has not been
reported previously in South Africa;
2) to use these methods to determine how different land uses and different
management practices within a single land use, have affected the structural
(genetic) and functional (catabolic) diversity of the soil bacterial and fungal
communities, and to relate these findings to selected soil physicochemical
properties, at two long-term agricultural experimental sites in KwaZulu-
Natal, South Africa, namely, Baynesfield Estate and the South African
Sugarcane Research Institute (SASRI) at Mount Edgecombe;
3) to determine if the results obtained using these profiling techniques support
those of previous research on the study soils, which involved only culture-
dependent and biochemical techniques.
The remainder of this thesis is structured as follows:
Chapter 2 presents a review of the literature covering the nature and significance of
biodiversity; land use and management factors affecting soil microbial diversity,
including a brief discussion of soil pollution; and, finally, some of the techniques
currently used for estimating soil microbial diversity, with emphasis on those to be
used in this study. Chapters 3 and 4 present the initial research conducted from 2004
to 2006, to determine the effects of different land uses and management practices on
the structural diversity of the resident soil bacterial and fungal communities at the two
experimental sites. Chapters 5 to 7 relate to the follow-up study from 2008 to 2010.
Chapter 5 is an extension of the initial study on fungal community structural diversity
to address some of the shortcomings in the initial work. Chapters 6 and 7 cover the
effects of land use and management practices, on the catabolic diversity of the soil
bacterial and fungal communities, at these sites. Chapter 8 presents general
conclusions based on the experimental results obtained over the duration of the entire
project.
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