Implication of stem water cryogenic extraction experiment for an earlier study is not supported with robust context-specific statistical assessment

Abstract

Chen et al. (1) conclude that “the extraction error-corrected result tends to nullify support for ecohydrological separation as a globally widespread phenomenon” based on an extrapolation of results from a carefully designed experiment under controlled conditions. The extrapolation was performed using global precipitation offset data (2) compiled from field-based studies that showed “widespread occurrence of ecohydrological separation.” The precipitation offset describes the difference in the isotopic composition of groundwater, stream water, soil water, and xylem water from that of local (i.e., context-specific) precipitation, which has a precipitation offset of zero. However, the conclusion in Chen et al.’s reanalysis is not supported with context-specific statistical analysis, which, in turn, was the basis for the conclusion in the original study (2).To establish support for Chen et al.’s (1) conclusion, we ran the same suite of … ↵1To whom correspondence may be addressed. Email: j.evaristo{at}uu.nl.