Geographic and seasonal variation in δ13C values of C3 plant arabidopsis: Archaeological implications

Abstract

Archaeologists frequently rely on carbon isotope data to infer past climates, ecosystems, diets, and mobility patterns. Scientists continue to unravel the intricacies of carbon isotope fractionation in C3 plants, and these data work to improve archaeological interpretations. An important question is how δ13C values of a single species vary with climate across sites, years, or seasons when water may not be the limiting factor, which could have important consequences for archaeological interpretation. This article examines δ13C values of one species of C3 plant, Arabidopsis thaliana, grown across five field sites in Europe over two and a half years. The five field sites (Valencia, Spain; Norwich, UK; Köln, Germany; Halle, Germany; and Oulu, Finland) were chosen to represent A. thaliana's native climate range and include both semi-arid and sub-humid climatic zones; site-specific climatic data were collected for each planting. There were significant differences in δ13C signatures of the A. thaliana plants grown at the different sites (p < 0.001) with higher δ13C values seen at lower latitudes or closer to the coast. Further, there were significant differences between years or seasons at Valencia, Spain (p = 0.001), Norwich, UK (p < 0.001) and Halle, Germany (p < 0.001). Principal component analysis of the planting-level climate data illustrates the interconnectedness of the environmental factors at play while also highlighting the importance of daylength on carbon fractionation during photosynthesis in A. thaliana at these sites.