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The work presented in this thesis was performed firstly to highlight the changes wrought in restored soil systems following the disruptive activities of opencast coal mining, and thereafter to identify, simulate and assess the effects of some typical perturbations associated with these activities. The microbial community was used as a focus for these investigations and the methods of soil adenosine 5'- triphosphate content analysis, dehydrogenase activity analysis and ergosterol content analysis were utilised alongside several other physical and chemical determinations. A field study of restored sites of various ages after cessation of opencast coal mining was undertaken which reinforced the utility of the microbial measurements. Experimentation was performed to investigate the effects of soil storage (at two depths), physical disturbance, compaction and the effects of the different combinations of these perturbations. Novel findings were obtained largely due to the paucity of research addressing the controlled manipulation and careful interpretation of these individual perturbations, and their effects when combined. The storage of soil was found to be the dominant factor influencing the status of the microbial communities upon restoration, and also influencing the development of these communities and the emergent plant biomass, post-restoration. This study found that soil, reinstated after opencast coal mining, becomes quickly dominated by fungi and, under grassland management, this domination then subsides over many years to a more bacterialcharacterised system. Differences were identified between the action of physical disturbance and compaction on stored and unstored soils. The deleterious effect of physical disturbance on unstored soil and the apparent ameliorative effect on soil affected by opencast operations can be interpreted through the change in soil architecture engendered by this treatment. The severe disturbances associated with opencast coal mining were found to affect the soil biota, primarily in terms of enduring environmental change. Thus the study of soil ecology was used as a sensitive indicator of recovery of disturbed land, and the changing energy flow through detrital food-webs was used as a model to follow this recovery process.

The scale-bound view of landsurfaces, being an assemblage of certain landforms, occurring within limited scale ranges, has been challenged by the scale-free characteristics of fractal geometry. This thesis assesses the fractal model by examining the irregularity of landsurface form, for the self-affine behaviour present in fractional Brownian surfaces. Different methods for detecting self-affine behaviour in surfaces are considered and of these the variogram technique is shown to be the most effective. It produces the best results of two methods tested on simulated surfaces, with known fractal properties. The algorithm used has been adapted to consider log (altitude variance) over a sample of log (distances) for: complete surfaces; subareas within surfaces; separate directions within surfaces. Twenty seven digital elevation models of landsurfaces arc re-examined for self- affine behaviour. The variogram results for complete surfaces show that none of these are self-affine over the scale range considered. This is because of dominant slope lengths and regular valley, spacing within areas. For similar reasons subarea analysis produces the non-fractal behaviour of markedly different variograms for separate subareas. The linearity of landforms in many areas, is detected by the variograms for separate directions. This indicates that the roughness of landsurfaces is anisotropic, unlike that of fractal surfaces. Because of difficulties in extracting particular landforms from their landsurfaces, no clear links between fractal behaviour, and landform size distribution could be established. A comparative study shows the geomorphometric parameters of fractal surfaces to vary with fractal dimension, while the geomorphometry of landsurfaces varies with the landforms present. Fractal dimensions estimated from landsurfaces do not correlate with geomorphometric parameters. From the results of this study, real landsurfaces would not appear to be scale- free. Therefore, a scale-bound approach towards landsurfaces would seem to be more appropriate to geomorphology than the fractal alternative.

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