title: Roots affect the response of heterotrophic soil respiration to temperature in tussock grass microcosms.
abstract: OBJECTIVE
  While the temperature response of soil respiration (R(S)) has been well studied, the partitioning of heterotrophic respiration (R(H)) by soil microbes from autotrophic respiration (R(A)) by roots, known to have distinct temperature sensitivities, has been problematic. Further complexity stems from the presence of roots affecting R(H), the rhizosphere priming effect. In this study the short-term temperature responses of R(A) and R(H) in relation to rhizosphere priming are investigated.
  
  
  METHODS
  Temperature responses of R(A), R(H) and rhizosphere priming were assessed in microcosms of Poa cita using a natural abundance δ(13)C discrimination approach.
  
  
  RESULTS
  The temperature response of R(S) was found to be regulated primarily by R(A), which accounted for 70 % of total soil respiration. Heterotrophic respiration was less sensitive to temperature in the presence of plant roots, resulting in negative priming effects with increasing temperature.
  
  
  CONCLUSIONS
  The results emphasize the importance of roots in regulating the temperature response of R(S), and a framework is presented for further investigation into temperature effects on heterotrophic respiration and rhizosphere priming, which could be applied to other soil and vegetation types to improve models of soil carbon turnover.
authors.affiliation: School of Biological Sciences, University of Canterbury, Christchurch 8140, New Zealand. scott.graham@pg.canterbury.ac.nz
authors.forename: Scott L
authors.initials: SL
authors.lastname: Graham
authors.forename: Peter
authors.initials: P
authors.lastname: Millard
authors.forename: John E
authors.initials: JE
authors.lastname: Hunt
authors.forename: Graeme N D
authors.initials: GN
authors.lastname: Rogers
authors.forename: David
authors.initials: D
authors.lastname: Whitehead
mesh_terms: D002244:Carbon / Q000378:metabolism*; D019069:Cell Respiration; D052836:Heterotrophic Processes; D018517:Plant Roots / Q000166:cytology / Q000378:metabolism*; D031785:Poa / Q000378:metabolism*; D058441:Rhizosphere; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology; D013696:Temperature
chemical_list: D012987:Soil; D002244:Carbon