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Assessing the effects of nitrogen deposition and climate on carbon isotope discrimination and intrinsic water‐use efficiency of angiosperm and conifer trees under rising CO 2 conditions
Author(s) -
Leonardi Stefano,
Gentilesca Tiziana,
Guerrieri Rossella,
Ripullone Francesco,
Magnani Federico,
Mencuccini Maurizio,
Noije Twan V.,
Borghetti Marco
Publication year - 2012
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/j.1365-2486.2012.02757.x
Subject(s) - deposition (geology) , nitrogen , environmental science , atmospheric sciences , climate change , isotopes of nitrogen , dendrochronology , ecology , chemistry , biology , geology , paleontology , organic chemistry , sediment
The objective of this study is to globally assess the effects of atmospheric nitrogen deposition and climate, associated with rising levels of atmospheric CO 2 , on the variability of carbon isotope discrimination ( Δ 13 C), and intrinsic water‐use efficiency ( iWUE ) of angiosperm and conifer tree species. Eighty‐nine long‐term isotope tree‐ring chronologies, representing 23 conifer and 13 angiosperm species for 53 sites worldwide, were extracted from the literature, and used to obtain long‐term time series of Δ 13 C and iWUE . Δ 13 C and iWUE were related to the increasing concentration of atmospheric CO 2 over the industrial period (1850–2000) and to the variation of simulated atmospheric nitrogen deposition and climatic variables over the period 1950–2000. We applied generalized additive models and linear mixed‐effects models to predict the effects of climatic variables and nitrogen deposition on Δ 13 C and iWUE . Results showed a declining Δ 13 C trend in the angiosperm and conifer species over the industrial period and a 16.1% increase of iWUE between 1850 and 2000, with no evidence that the increased rate was reduced at higher ambient CO 2 values. The temporal variation in Δ 13 C supported the hypothesis of an active plant mechanism that maintains a constant ratio between intercellular and ambient CO 2 concentrations. We defined linear mixed‐effects models that were effective to describe the variation of Δ 13 C and iWUE as a function of a set of environmental predictors, alternatively including annual rate ( N rate ) and long‐term cumulative ( N cum ) nitrogen deposition. No single climatic or atmospheric variable had a clearly predominant effect, however, Δ 13 C and iWUE showed complex dependent interactions between different covariates. A significant association of N rate with iWUE and Δ 13 C was observed in conifers and in the angiosperms, and N cum was the only independent term with a significant positive association with iWUE , although a multi‐factorial control was evident in conifers.