Comparison of measured and modeled variations in piñon pine leaf water isotopic enrichment across a summer moisture gradient

Elise Pendall, David G. Williams, Steven W. Leavitt

Research output: Contribution to journalArticle

30 Scopus citations

Abstract

Stable hydrogen and oxygen isotopic composition of bulk leaf water (δDlw and δ18Olw) in piñon pine (Pinus edulis and P. monophylla) and gas exchange parameters were measured under field conditions to examine the effects of seasonal moisture stress on leaf water isotopic enrichment. Study sites were located near the lower elevation limit for piñon in the southwestern USA. Leaf-level transpiration measurements were made four times daily in spring, summer and early autumn; simultaneously, leaf samples were collected for water extraction and stable isotope analysis. Diurnal variations in δDlw and δ18Olw values were small, especially when leaf water residence times (molar leaf water content divided by transpiration rate) were high. Stomatal conductance explained most of the variance (60%) in leaf water enrichment across the dataset. Observed leaf water enrichment was compared with predictions of steady-state and nonsteady-state models. Nonsteady-state predictions fit observations the best, although D enrichment was often lower than predicted by any model. Hydrogen isotope ratios of leaf water and cellulose nitrate were strongly correlated, demonstrating preservation of a leaf water signal in wood and leaf cellulose.

Original languageEnglish (US)
Pages (from-to)605-618
Number of pages14
JournalOecologia
Volume145
Issue number4
DOIs
StatePublished - Oct 1 2005

Keywords

  • D/H
  • Leaf water
  • O/O
  • Relative humidity
  • Stable isotopes
  • Stomatal conductance

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

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