Effects of coexisting plant species on soil microbes and soil enzymes in metal lead contaminated soils

It is not clear whether plant species coexistence can offset the impacts of heavy metal lead (Pb) on soil microbes and soil enzyme activities. We conducted a factorial experiment to investigate the effects of three plant species combinations (1, 2 and 4 species) on soil microbial and soil enzyme properties under three Pb concentrations (0, 300 and 600 mg kg(-1) soil). Microbial biomass carbon (MBC), BIOLOG profiles of soil microbes and soil enzyme activities were measured. Under monoculture, elevated Pb did not reduce soil MBC, had no effects on activities of urease, acid phosphatase and dehydrogenase, but stimulated the activity of alkaline phosphatase. Compared to monoculture, plant species coexistence did not significantly affect soil microbial biomass C but increased microbial functional group diversity index and urease activity under different Pb concentrations. In addition, microbial community structure diverged among plant coexistence treatments under each Pb concentration. These results suggested that coexistence of plant species might alleviate the effects of metal lead on soil microbes and reducing metal lead effect on urease activity. (c) 2007 Elsevier B.V. All rights reserved.