Ecosystem implications of genetic variation in water-use of a dominant riparian tree

D. G. Fischer, S. C. Hart, T. G. Whitham, G. D. Martinsen, P. Keim

Research output: Contribution to journalArticle

28 Scopus citations


Genetic variation in dominant species can affect plant and ecosystem functions in natural systems through multiple pathways. Our study focuses on how genetic variation in a dominant riparian tree (Populus fremontii, P. angustifolia and their natural F1 and backcross hybrids) affects whole-tree water use, and its potential ecosystem implications. Three major patterns were found. First, in a 12-year-old common garden with trees of known genetic makeup, hybrids had elevated daily integrated leaf-specific transpiration (Etl ; P=0.013) and average canopy conductance (G c ; P=0.037), with both Etl and Gc ∼30% higher in hybrid cross types than parental types. Second, δ13C values of leaves from these same trees were significantly more negative in hybrids (P=0.004), and backcross hybrids had significantly more negative values than all other F1 hybrid and parental types (P <0.001). Third, in the wild, a similar pattern was found in leaf δ13C values where both hybrid cross types had the lowest values (P <0.001) and backcross hybrids had lower δ13C values than any other tree type (P <0.001). Our findings have two important implications: (1) the existence of a consistent genetic difference in whole-tree physiology suggests that whole-tree gas and water exchange could be another pathway through which genes could affect ecosystems; and (2) such studies are important because they seek to quantify the genetic variation that exists in basic physiological processes - such knowledge could ultimately place ecosystem studies within a genetic framework.

Original languageEnglish (US)
Pages (from-to)288-297
Number of pages10
Issue number2
StatePublished - Apr 1 2004


  • Extended phenotype
  • Intraspecific genetic variation
  • Intrinsic water-use-efficiency
  • Populus
  • Sap flow

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

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