Linking microbial community composition to function in a tropical soil

Lf changes in the composition of the soil microbial community alter the phy siological capacity of the community then such changes may have ecosystem c onsequences. We examined the relationships among community composition (PLF A), microbial biomass (CFDE), substrate utilization profiles (BIOLOG), lign ocellulose degrading enzyme activities (beta -glucosidase, cellobiohydrolas e, beta -xylosidase, phenol oxidase, peroxidase), and nutrient releasing en zyme activities (phosphatase, sulphatase) in a Tropeptic Haplustol soil. Th e soils supported a tropical forest and pineapple plantations of varying ag es that were at different stages within the management cycle. Conversion fr om forest to agriculture significantly decreased %C and %N of the soil by 5 0-55%, microbial biomass by 75%, beta -glucosidase by 54%, sulphatase activ ity by 85%, decreased Ca, Mg, and Mn availability, and produced composition ally and functionally distinct microbial communities. Total enzyme activiti es were generally correlated with %C, %N, microbial biomass and, occasional ly with community composition. We calculated the specific activities of the enzymes assayed (enzyme activity per unit microbial biomass C) in order to normalize activity to the size of the microbial community. Values for enzy me specific activities were more highly correlated with community compositi on than were total enzyme activities. In addition, BIOLOG was not correlate d with community composition or enzyme activities. Enzyme activities and sp ecific activities may provide a useful linkage between microbial community composition and carbon processing. (C) 2000 Elsevier Science Ltd. All right s reserved.