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Whether or not extractives, lignin, and (or) hemicelluloses, all of which have specific isotopic signatures, should be removed prior to dendroisotopic analysis is still debated. This study reports the range of modern tree-ring δ13C values of cellulose from Thuja occidentalis L., a species that has been under-utilized in dendroisotopic research despite its broad distribution and great longevity in North America. The main objective of the study was to recommend a wood component from T. occidentalis to isolate for future δ13C dendroisotopic analyses. Annually resolved tree-ring decadal segments common to eight T. occidentalis trees were excised from cross sections and homogenized. The tree-ring decadal segment from each tree was then chemically processed from untreated whole wood to extractive-free wood, to holocellulose, and to α-cellulose. Subsamples were analyzed for δ13C, percent carbon, and percent yield after each stage of chemical treatment. We recommend that holocellulose be extracted for T. occidentalis, as the α-cellulose yield may be too low when tree-ring samples are very small. The δ13C values for T. occidentalis tree rings were found to be enriched with respect to those for needle-leaved conifers but in close agreement with those reported in the literature for other scale-leaved evergreens. [ABSTRACT FROM AUTHOR]

The article explores how the two sources of variation affect analysis of deuterium: protium data. It also offers conclusions about migratory connectivity in American Redstarts, a long-distance migratory songbird that winters in the Caribbean and Central America and breeds in North America. In this context, researchers examine how two known sources of variation in deuterium: protium influence assignment probabilities and the practical application of assignment results. Common statistical methods for estimating the origin of individuals using stable isotopes include simple regression.