Microbiological analysis of soil perturbations associated with opencast coal mining and their consequences for restoration
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.