Interpreting species-specific variation in tree-ring oxygen isotope ratios among three temperate forest trees
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Plant, Cell & Environment. 37(9): 2169-2182.
Although considerable variation has been documented in tree-ring cellulose oxygen isotope ratios (δ18Ocell) among co-occurring species, the underlying causes are unknown. Here, we used a combination of field measurements and modelling to investigate the mechanisms behind variations in late-wood δ18Ocell (δ18Olc) among three co-occurring species (chestnut oak, black oak and pitch pine) in a temperate forest. For two growing seasons,we quantified among-species variation in δ18Olc, as well as several variables that could potentially cause the δ18Olc variation. Data analysis based on the δ18Ocell model rules out leaf water enrichment (Δ18Olw) and tree-ring formation period (Δt), but highlights source water δ18O (δ18Osw) as an important driver for the measured difference in δ18Olc between black and chestnut oak. However, the enriched δ18Olc in pitch pine relative to the oaks could not be sufficiently explained by consideration of the above three variables only, but rather, we show that differences in the proportion of oxygen exchange during cellulose synthesis (pex) is most likely a key mechanism. Our demonstration of the relevance of some species-specific features (or lack thereof) to δ18Ocell has important implications for isotope based ecophysiological/paleoclimate studies.
Song, Xin; Clark, Kenneth S.; Helliker, Brent R. 2014. Interpreting species-specific variation in tree-ring oxygen isotope ratios among three temperate forest trees. Plant, Cell & Environment. 37(9): 2169-2182. https://doi.org/10.1111/pce.12317.