title: Arctic microorganisms respond more to elevated UV-B radiation than CO2.
abstract: Surface ultraviolet-B radiation and atmospheric CO2 concentrations have increased as a result of ozone depletion and burning of fossil fuels. The effects are likely to be most apparent in polar regions where ozone holes have developed and ecosystems are particularly sensitive to disturbance. Polar plant communities are dependent on nutrient cycling by soil microorganisms, which represent a significant and highly labile portion of soil carbon (C) and nitrogen (N). It was thought that the soil microbial biomass was unlikely to be affected by exposure of their associated plant communities to increased UV-B. In contrast, increasing atmospheric CO2 concentrations were thought to have a strong effect as a result of greater below-ground C allocation. In addition, there is a growing belief that ozone depletion is of only minor environmental concern because the impacts of UV-B radiation on plant communities are often very subtle. Here we show that 5 years of exposure of a subarctic heath to enhanced UV-B radiation both alone and in combination with elevated CO2 resulted in significant changes in the C:N ratio and in the bacterial community structure of the soil microbial biomass.
authors.affiliation: Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK. D.Johnson@Shef.ac.uk
authors.forename: David
authors.initials: D
authors.lastname: Johnson
authors.forename: Colin D
authors.initials: CD
authors.lastname: Campbell
authors.forename: John A
authors.initials: JA
authors.lastname: Lee
authors.forename: Terry V
authors.initials: TV
authors.lastname: Callaghan
authors.forename: Dylan
authors.initials: D
authors.lastname: Gwynn-Jones
mesh_terms: D001110:Arctic Regions; D018533:Biomass; D019068:Bryopsida / Q000378:metabolism; D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000494:pharmacology*; D017753:Ecosystem; D009584:Nitrogen / Q000378:metabolism; D010944:Plants / Q000378:metabolism* / Q000382:microbiology; D012988:Soil Microbiology; D014466:Ultraviolet Rays
chemical_list: D002245:Carbon Dioxide; D002244:Carbon; D009584:Nitrogen