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Can tree-ring δ15N be used as a proxy for foliar δ15N in European beech and Norway spruce?
- Source :
- Trees. 30:627-638
- Publication Year :
- 2015
- Publisher :
- Springer Science and Business Media LLC, 2015.
-
Abstract
- For long-term environmental investigations, tree-ring δ 15 N values are inappropriate proxies for foliar δ 15 N for both Fagus sylvatica and Picea abies under moderate N loads. Currently it is unclear whether stable nitrogen isotope signals of tree-rings are related to those in foliage, and whether they can be used to infer tree responses to environmental changes. We studied foliar and tree-ring nitrogen (δ15N) and carbon (δ13C) isotope ratios in European beech (Fagus sylvatica L.) and Norway spruce (Picea abies L.) from six long-term forest monitoring sites in Switzerland together with data on N deposition and soil N availability, as well as a drought response index over the last two decades. For both species, tree-ring δ15N and δ13C values were less negative compared to foliar δ15N and δ13C values, most likely due to recycling and reallocation of N within the tree and fractionation processes associated with the transport of sucrose and the formation of tree-rings, respectively. Temporal trends recorded in foliar δ15N were not reflected in tree-ring δ15N, with much higher variations in tree-rings compared to foliage. Soil N availability and N deposition were partially able to explain changes in foliar δ13C, while there were no significant correlations between environmental variables and either tree-ring or foliar δ15N. Our results suggest an uncoupling between the N isotopic composition of tree-rings and foliage. Consequently, tree-ring δ15N values are inappropriate proxies of foliar δ15N values under low-to-moderate N deposition loads. Furthermore, at such low levels of deposition, tree-ring δ15N values are not recommended as archives of tree responses to soil C/N or bulk N deposition.
- Subjects :
- 010504 meteorology & atmospheric sciences
Ecology
δ13C
biology
Physiology
chemistry.chemical_element
Forestry
Picea abies
Plant Science
δ15N
010501 environmental sciences
biology.organism_classification
01 natural sciences
Nitrogen
Isotopes of nitrogen
Agronomy
chemistry
Fagus sylvatica
Botany
Dendrochronology
Environmental science
Beech
0105 earth and related environmental sciences
Subjects
Details
- ISSN :
- 14322285 and 09311890
- Volume :
- 30
- Database :
- OpenAIRE
- Journal :
- Trees
- Accession number :
- edsair.doi...........4a1fbcaaa071220a53f8caf97966dc19