title: Leaf traits, shoot growth and seed production in mature Fagus sylvatica trees after 8 years of CO2 enrichment.
abstract: OBJECTIVE
  Masting, i.e. synchronous but highly variable interannual seed production, is a strong sink for carbon and nutrients. It may, therefore, compete with vegetative growth. It is currently unknown whether increased atmospheric CO(2) concentrations will affect the carbon balance (or that of other nutrients) between reproduction and vegetative growth of forest species. In this study, reproduction and vegetative growth of shoots of mature beech (Fagus sylvatica) trees grown at ambient and elevated atmospheric CO(2) concentrations were quantified. It was hypothesized that within a shoot, fruiting has a negative effect on vegetative growth, and that this effect is ameliorated at increased CO(2) concentrations.
  
  
  METHODS
  Reproduction and its competition with leaf and shoot production were examined during two masting events (in 2007 and 2009) in F. sylvatica trees that had been exposed to either ambient or elevated CO(2) concentrations (530 µmol mol(-1)) for eight consecutive years, between 2000 and 2008.
  
  
  RESULTS
  The number of leaves per shoot and the length of terminal shoots was smaller or shorter in the two masting years compared with the one non-masting year (2008) investigated, but they were unaffected by elevated CO(2) concentrations. The dry mass of terminal shoots was approx. 2-fold lower in the masting year (2007) than in the non-masting year in trees growing at ambient CO(2) concentrations, but this decline was not observed in trees exposed to elevated CO(2) concentrations. In both the CO(2) treatments, fruiting significantly decreased nitrogen concentration by 25 % in leaves and xylem tissue of 1- to 3-year-old branches in 2009.
  
  
  CONCLUSIONS
  Our findings indicate that there is competition for resources between reproduction and shoot growth. Elevated CO(2) concentrations reduced this competition, indicating effects on the balance of resource allocation between reproduction and vegetative growth in shoots with rising atmospheric CO(2) concentrations.
authors.affiliation: Department of Plant Ecology, Forestry and Forest Products Research Institute (FFPRI), 1 Matsunosato, Tsukuba, Ibaraki, Japan. qhan@ffpri.affrc.go.jp
authors.forename: Qingmin
authors.initials: Q
authors.lastname: Han
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kabeya
authors.forename: Günter
authors.initials: G
authors.lastname: Hoch
mesh_terms: D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000494:pharmacology*; D029964:Fagus / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology*; D005638:Fruit / Q000187:drug effects / Q000254:growth & development; D009584:Nitrogen / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development; D012098:Reproduction / Q000502:physiology*; D012639:Seeds / Q000187:drug effects / Q000254:growth & development; D013557:Switzerland; D013997:Time Factors; D014197:Trees / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D052584:Xylem / Q000187:drug effects / Q000254:growth & development
chemical_list: D002245:Carbon Dioxide; D002244:Carbon; D009584:Nitrogen