title: Seasonal patterns of foliage respiration in dominant and suppressed Eucalyptus globulus canopies.
abstract: We examined spatial and temporal dynamics of foliage respiration in canopies of dominant and suppressed Eucalyptus globulus trees to better understand processes regulating foliage respiration in a young fast-growing stand. Temperature response functions and seasonal measures of respiration (measured at a reference temperature of 15 °C, R₁₅) were studied for approximately 1 year to (i) examine controls on respiration as a function of canopy position, foliar nitrogen and non-structural carbohydrate concentrations and (ii) assess the capacity for thermal acclimation within E. globulus canopies. The short-term temperature response of respiration varied both with canopy position and seasonally. Area-based R(15) measurements declined with increasing canopy depth and were strongly related to foliar N concentrations, especially in upper-canopy positions. R₁₅ was negatively correlated with the average temperature of the preceding 14 days, a pattern consistent with thermal acclimation. In suppressed canopies, R₁₅ was higher than that at similar canopy heights in dominant trees. Similarly, foliar concentrations of non-structural carbohydrates were also relatively higher in suppressed canopies than dominant canopies, providing support for a substrate-based model of leaf respiration. Our data highlight the dynamic nature of foliar respiration within E. globulus canopies, which contrasts with the generally simplistic representation of respiration within most process-based models.
authors.affiliation: School of Plant Science, University of Tasmania, Hobart, Tasmania 7001, Australia. anthony.ogrady@csiro.au
authors.forename: A P
authors.initials: AP
authors.lastname: O'Grady
authors.forename: A
authors.initials: A
authors.lastname: Eyles
authors.forename: D
authors.initials: D
authors.lastname: Worledge
authors.forename: M
authors.initials: M
authors.lastname: Battaglia
mesh_terms: D000064:Acclimatization; D017753:Ecosystem; D005052:Eucalyptus / Q000502:physiology*; D018515:Plant Leaves / Q000502:physiology*; D018526:Plant Transpiration / Q000502:physiology*; D012621:Seasons