Intramolecular 13C analysis of tree rings provides multiple plant ecophysiology signals covering decades

Abstract

Measurements of carbon isotope contents of plant organic matter provide important information in diverse fields such as plant breeding, ecophysiology, biogeochemistry and paleoclimatology. They are currently based on 13C/12C ratios of specific, whole metabolites, but we show here that intramolecular ratios provide higher resolution information. In the glucose units of tree-ring cellulose of 12 tree species, we detected large differences in 13C/12C ratios (>10‰) among carbon atoms, which provide isotopically distinct inputs to major global C pools, including wood and soil organic matter. Thus, considering position-specific differences can improve characterisation of soil-to-atmosphere carbon fluxes and soil metabolism. In a Pinus nigra tree-ring archive formed from 1961 to 1995, we found novel 13C signals, and show that intramolecular analysis enables more comprehensive and precise signal extraction from tree rings, and thus higher resolution reconstruction of plants’ responses to climate change. Moreover, we propose an ecophysiological mechanism for the introduction of a 13C signal, which links an environmental shift to the triggered metabolic shift and its intramolecular 13C signature. In conclusion, intramolecular 13C analyses can provide valuable new information about long-term metabolic dynamics for numerous applications.

Intramolecular carbon isotope signals reflect metabolite allocation in plants

“…Thus, intramolecular 13 C/ 12 C analysis yields information about several environmental variables which may enable more powerful paleoenvironment reconstructions than whole-molecule analysis. Δi denotes timeseries of intramolecular 13 C discrimination (Wieloch et al, 2018). Data were measured on tree-ring glucose of Pinus nigra laid down from 1961 to 1995 at a dry site in the Vienna basin.…”

“…Data were measured on tree-ring glucose of Pinus nigra laid down from 1961 to 1995 at a dry site in the Vienna basin. This table was originally published as Table 1 in Wieloch et al (2018) and provided here for convenience. by Saurer et al (1995).…”

“…However, this approach neglects 13 C/ 12 C differences known to occur among individual carbon positions of plant metabolites (Schmidt et al, 2015). By contrast, Wieloch et al (2018) recently analysed intramolecular 13 C/ 12 C ratios in glucose extracted from an annually-resolved tree-ring series of Pinus nigra from Vienna (Austria). These authors reported intramolecular 13 C signals, i.e., systematic 13 C/ 12 C variation confined to individual carbon positions within a metabolite.…”

“…In the following, we propose ecophysiological mechanisms for the introduction of each component starting with the independent component. Please note that the Δ5-6' signal can be expected to be under environmental rather than developmental control (SI 5) Wieloch et al (2018). studied effects of VPD, precipitation, soil moisture, temperature, and global radiation on the diffusion-Rubisco signal in their Pinus nigra samples.…”

Tree-ring isotopes adjacent to Lake Superior reveal cold winter anomalies for the Great Lakes region of North America

“…Isotopic signals imprinted upon tree-ring cellulose can serve as robust climate proxies that are conventionally known to record growing season conditions 1 . Indeed, the stable isotope composition of tree-ring cellulose has been shown to reflect canopy-integrated leaf responses to environmental drivers that are further modified by downstream ecophysiological processes 2 – 7 . More specifically, in temperate, near-coastal locations, the primary environmental signals recorded by tree-ring carbon and oxygen isotopes include warm season temperature, vapor pressure deficit, irradiance, and cloud cover 8 – 14 .…”