title: Impact of lime, nitrogen and plant species on bacterial community structure in grassland microcosms.
abstract: A microcosm-based approach was used to study impacts of plant and chemical factors on the bacterial community structure of an upland acidic grassland soil. Seven perennial plant species typical of both natural, unimproved (Nardus stricta, Agrostis capillaris, Festuca ovina and F. rubra) and fertilized, improved (Holcus lanatus, Lolium perenne and Trifolium repens) grasslands were either left unamended or treated with lime, nitrogen, or lime plus nitrogen in a 75-day glasshouse experiment. Lime and nitrogen amendment were shown to have a greater effect on microbial activity, biomass and bacterial ribotype number than plant species. Liming increased soil pH, microbial activity and biomass, while decreasing ribotype number. Nitrogen addition decreased soil pH, microbial activity and ribotype number. Addition of lime plus nitrogen had intermediate effects, which appeared to be driven more by lime than nitrogen. Terminal restriction fragment length polymorphism (TRFLP) analysis revealed that lime and nitrogen addition altered soil bacterial community structure, while plant species had little effect. These results were further confirmed by multivariate redundancy analysis, and suggest that soil lime and nitrogen status are more important controllers of bacterial community structure than plant rhizosphere effects.
authors.affiliation: Microbial Ecology Group, Department of Industrial Microbiology, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Nabla
authors.initials: N
authors.lastname: Kennedy
authors.forename: Eoin
authors.initials: E
authors.lastname: Brodie
authors.forename: John
authors.initials: J
authors.lastname: Connolly
authors.forename: Nicholas
authors.initials: N
authors.lastname: Clipson
mesh_terms: D000704:Analysis of Variance; D001419:Bacteria / Q000187:drug effects* / Q000235:genetics; D018407:Bacterial Physiological Phenomena; D018533:Biomass; D017610:Calcium Compounds / Q000494:pharmacology*; D017931:DNA Primers; D017753:Ecosystem; D006863:Hydrogen-Ion Concentration; D015999:Multivariate Analysis; D009584:Nitrogen / Q000494:pharmacology*; D010087:Oxides / Q000494:pharmacology*; D006109:Poaceae / Q000502:physiology; D012150:Polymorphism, Restriction Fragment Length; D012987:Soil / Q000032:analysis
chemical_list: D017610:Calcium Compounds; D017931:DNA Primers; D010087:Oxides; D012987:Soil; C016538:lime; D009584:Nitrogen