title: Comparison of δ(18)O and δ(13)C values between tree-ring whole wood and cellulose in five species growing under two different site conditions.
abstract: BACKGROUND
  We investigated the applicability of tree-ring whole-wood material for δ(18)O and δ(13)C analysis in comparison with the more time- and resource-intensive use of cellulose, by considering possible variability between (i) five different tree species (Fagus sylvatica, Quercus robur, Picea abies, Abies alba, Pseudotsuga menziesii), (ii) two sites that differ in soil moisture, and (iii) climate conditions within a 10-year period.
  
  
  METHODS
  Stem cores of 30 individual trees (n = 3 trees per each species and site) were sampled from two sites in south Germany (Bavaria), and tree rings within sapwood of the years 2001-2010 were separated. The δ(18)O and δ(13)C values from homogenized tree-ring whole wood and from extracted cellulose were measured by mass spectrometry. Species-specific offsets in isotope values were analyzed and the responses in isotopic signature to climate variability including a single drought event were compared between whole-wood and cellulose.
  
  
  RESULTS
  A constant offset in δ(18)O values of ca 5‰ between wood and cellulose was observed for most species independent of site conditions, with a significant difference between beech and Douglas-fir, while inter-annual variability was only observed in oak. The offset in δ(13)C values ranged between 1.45 and 1.84‰ across species, sites and years. Both materials generally showed similar strength in responses to temperature, precipitation and soil water availability, particularly for conifers. Resistance to severe drought stress--partly more strongly reflected in the δ(13)C values of cellulose--was lower for conifers than for the deciduous species.
  
  
  CONCLUSIONS
  Wood material from the sapwood of the studied tree species is as useful as cellulose for studying environmental effects on tree-ring δ(18)O and δ(13)C values at a short-term scale as considered in most ecophysiological studies. The more variable response of oak may require further investigations.
authors.affiliation: Laboratory of Atmospheric Chemistry, Ecosystem Fluxes, Paul Scherrer Institute, 5232, Villigen, Switzerland.
authors.forename: Rosemarie B
authors.initials: RB
authors.lastname: Weigt
authors.affiliation: Laboratory of Atmospheric Chemistry, Ecosystem Fluxes, Paul Scherrer Institute, 5232, Villigen, Switzerland.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Bräunlich
authors.affiliation: Bavarian State Institute of Forestry, 85354, Freising, Germany.
authors.forename: Lothar
authors.initials: L
authors.lastname: Zimmermann
authors.affiliation: Laboratory of Atmospheric Chemistry, Ecosystem Fluxes, Paul Scherrer Institute, 5232, Villigen, Switzerland.
authors.forename: Matthias
authors.initials: M
authors.lastname: Saurer
authors.affiliation: Ecophysiology of Plants, Department Ecology and Ecosystem Management, Technische Universität München, 85354, Freising, Germany.
authors.forename: Thorsten E E
authors.initials: TE
authors.lastname: Grams
authors.affiliation: Bavarian State Institute of Forestry, 85354, Freising, Germany.
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Dietrich
authors.affiliation: Laboratory of Atmospheric Chemistry, Ecosystem Fluxes, Paul Scherrer Institute, 5232, Villigen, Switzerland.
authors.forename: Rolf T W
authors.initials: RT
authors.lastname: Siegwolf
authors.affiliation: Bavarian State Institute of Forestry, 85354, Freising, Germany.|Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 8903, Birmensdorf, Switzerland.
authors.forename: Petia S
authors.initials: PS
authors.lastname: Nikolova
mesh_terms: D028202:Abies / Q000737:chemistry* / Q000254:growth & development; D002247:Carbon Isotopes / Q000032:analysis; D002482:Cellulose / Q000737:chemistry*; D002980:Climate; D055864:Droughts; D029964:Fagus / Q000737:chemistry* / Q000254:growth & development; D013058:Mass Spectrometry; D010103:Oxygen Isotopes / Q000032:analysis; D028222:Picea / Q000737:chemistry* / Q000254:growth & development; D018547:Plant Stems / Q000737:chemistry / Q000254:growth & development; D028224:Pseudotsuga / Q000737:chemistry* / Q000254:growth & development; D029963:Quercus / Q000737:chemistry* / Q000254:growth & development; D012987:Soil / Q000737:chemistry; D013045:Species Specificity; D014867:Water / Q000032:analysis; D014934:Wood / Q000737:chemistry* / Q000254:growth & development
chemical_list: D002247:Carbon Isotopes; D010103:Oxygen Isotopes; D012987:Soil; D014867:Water; D002482:Cellulose