Functional stability, substrate utilisation and biological indicators of soils following environmental impacts

Stability of a soil property to perturbation comprises both resistance and resilience. Resistance is defined as the ability of the soil to withstand t he immediate effects of perturbation, and resilience the ability of the soi l to recover from perturbation. Functional stability is used here to descri be the stability of a biological function to perturbation, rather than the stability of physical structure or chemical properties. The function chosen for this study was the short-term decomposition of added plant residues, a nd the perturbations were copper and heat stresses. Previous studies had sh own that functional stability was reduced greatly in soils with experimenta lly reduced biodiversity. The objective of this study was to determine the relative sensitivity of functional stability and potential indicators of bi ological status to detect alteration of held soils by various environmental impacts. Functional stability, protozoan populations and substrate mineral isation kinetics, were measured on paired soils with: high or low plant spe cies diversity; hydrocarbon pollution or not; extensive or intensive agricu ltural management practices. Substrate mineralisation kinetics were poorly related to the soil's antecedent conditions and were stimulated significant ly by hydrocarbon pollution. Protozoan populations were potentially useful for detecting differences within soil type, but will require greater taxono mic input to be most useful. Functional stability particularly resistance, was able to quantify differences between and within soils. The potential de velopment of the technique in relation to soil health is discussed. (C) 200 1 Elsevier Science B.V. All rights reserved.