Rapid response to anthropogenic climate change by Thuja occidentalis: implications for past climate reconstructions and future climate predictions.
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ABSTRACT: Carbon isotope values of leaves (?13Cleaf) from meta-analyses and growth chamber studies of C3 plants have been used to propose generalized relationships between ?13Cleaf and climate variables such as mean annual precipitation (MAP), atmospheric concentration of carbon dioxide ([CO2]), and other climate variables. These generalized relationships are frequently applied to the fossil record to create paleoclimate reconstructions. Although plant evolution influences biochemistry and response to environmental stress, few studies have assessed species-specific carbon assimilation as it relates to climate outside of a laboratory. We measured ?13Cleaf values and C:N ratios of a wide-ranging evergreen conifer with a long fossil record, Thuja occidentalis (Cupressaceae) collected 1804-2017, in order to maximize potential paleo-applications of our focal species. This high-resolution record represents a natural experiment from pre-Industrial to Industrial times, which spans a range of geologically meaningful [CO2] and ?13Catm values. ?leaf values (carbon isotope discrimination between ?13Catm and ?13Cleaf) remain constant across climate conditions, indicating limited response to environmental stress. Only ?13Cleaf and ?13Catm values showed a strong relationship (linear), thus, ?13Cleaf is an excellent record of carbon isotopic changes in the atmosphere during Industrialization. In contrast with previous free-air concentration enrichment experiments, no relationship was found between C:N ratios and increasing [CO2]. Simultaneously static C:N ratios and ?leaf in light of increasing CO2 highlights plants' inability to match rapid climate change with increased carbon assimilation as previously expected; ?leaf values are not reliable tools to reconstruct MAP and [CO2], and ?13Cleaf values only decrease with [CO2] in line with atmospheric carbon isotope changes.
SUBMITTER: Stein RA
PROVIDER: S-EPMC6662565 | biostudies-literature | 2019
REPOSITORIES: biostudies-literature
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