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RESEARCH PRODUCT

Effects of heavy metals on soil microflora

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Elevated concentrations of heavy metals are known to cause disturbances in all living organisms. A reduction in the activity of forest microbes, expressed as decreased carbon and nitrogen mineralisation, may result in a slower rate of litter decomposition and slower nutrient cycling in the whole ecosystem (Baath 1989). In areas severely polluted by heavy metals, this can be seen as an accumulation of undecomposed litter on the forest floor. Thus, in addition to the direct toxicity of heavy metals, the trees may suffer from nutrient deficiency resulting from the decrease in the mineralisation of nutrients from the litter. Heavy metals can also retard litter decomposition processes in less polluted areas where there are no visible signs of damage to the vegetation. Heavy metals have also been found to change the species composition of the cultivatable bacteria and fungi.