Non-structural carbohydrates predict survival in saplings of temperate trees under carbon stress

1. Non-structural carbohydrates (NSCs) mediate plant survival when the plant’s carbon (C) balance is negative, suggesting that NSCs could predict plant survival under C stress. To examine this possibility, we exposed saplings of six temperate tree species to diverse levels of C stress created by the combination of two light conditions (full light availability and deep shade) and two defoliation levels (severe defoliation and non-defoliation). We then measured survival, biomass, and total NSCs and soluble sugar (SSs) concentrations in different organs of both dead and live saplings.
2. We estimated mean NSCs and SSs contents and concentrations per sapling and fitted logistic generalized mixed-effects models to determine if NSCs and SSs predict survival. Using inverse prediction modelling, we also determined whether there is a common NSCs and SS threshold across species at the time of sapling’s death.
3. Defoliation and shade reduced the mean sapling’s NSCs and SSs contents, indicating C ...