The ecology of some soil mites from coal shale tips.
Acari were sampled from experimental plots on coal-shale tips undergoing reclamation. Cryptostigmata were the dominant mite order. Acid and more basic coal shales carried dissimilar mite communities, the dominant species being different at each site although present in both. Populations of Oppiella nova and Mixochthonius laticeps were monitored monthly for a year in acid shale plots subject to various combinations of cutting and liming regimes at two levels on the tip slope. Oppiella nova was not successful in maintaining viable populations at the base of the slope but M. laticeps was virtually unaffected by this factor. Oppiella nova favoured limed plots whereas M. laticeps favoured unlimed plots. For each species there was a small effect of cutting the vegetation. Numbers of adult O. nova were generally highest in the autumn whereas the density of M. laticeps was greatest in June and July. It is concluded that mites may not be valuable as indicators of specific soil conditions, because of the many interacting variables influencing their populations.