13C-labeling shows the effect of hierarchy on the carbon gain of individuals and functional groups in dense field stands

Fernando Alfredo Lattanzi, German Darío Berone, Wolfgang Feneis, Hans Schnyder

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Measurements of resource capture by individuals, species, or functional groups coexisting in field stands improve our ability to investigate the ecophysiological basis of plant competition. But methodological and technical difficulties have limited the use of such measurements. Carbon capture, in particular, is difficult to asses in heterogeneous, dense field stands. Here we present a new approach to measure in situ daily gross carbon gain of individuals. It is based on measuring the 13C content of shoots after a few hours of continuous labeling of all assimilated CO 2. The technique is simple and has few assumptions. A new, fully mobile facility was developed, capable of providing a labeling environment with a CO 2 concentration close to atmospheric air and known, constant 13C- enrichment, while maintaining temperature and relative humidity within ambient values. This facility was used in seminatural grasslands of Germany and Argentina to explore the relationship between size and carbon gain of individuals of coexisting species growing in contrasting hierarchical positions, and to analyze the carbon gain of functional groups. In general, carbon gain per unit shoot mass increased with increasing size among small individuals, but it became independent of size among the largest ones. In consequence, competition appeared to be size asymmetric between subordinate individuals but size symmetric between dominant individuals. When comparing functional groups, the carbon gain per unit shoot mass of rosette dicots vs. grasses reflected not their relative contribution to stand biomass, but their hierarchical position: irrespectively of mass or growth form, being taller than neighbors was most important in determining carbon gain per unit shoot mass. We believe these results show that in situ measurements of carbon gain can provide valuable insight in field studies of plant competition.

Original languageEnglish
Pages (from-to)169-179
Number of pages11
JournalEcology
Volume93
Issue number1
DOIs
StatePublished - Jan 2012
Externally publishedYes

Keywords

  • C steady-state labeling
  • Carbon gain
  • Field stands
  • Functional groups
  • Individuals size
  • Photosynthesis
  • Plant height
  • Species coexistence
  • Symmetric and asymmetric competition

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