The allometry of root production and loss in seedlings of Acer rubrum (Aceraceae) and Betula papyrifera (Betulaceae): implications for root dynamics in elevated CO₂

Total root production (∑ P ), total root loss (∑ L ), net root production. (NP), and biomass production were determined for seedlings of Betula papyrifera and Acer rubrum in ambient and elevated CO 2 environments. ∑ P , ∑ L , and NP were calculated from sequential, independent observations of root length production through plexiglass windows. Elevated CO 2 increased ∑ P , ∑ L , and NP in seedlings of Betula papyrifera but not Acer rubrum. Root production and loss were qualitatively similar to whole‐plant growth responses to elevated CO 2 . Betula showed enhanced ∑ P , ∑ L , and biomass with elevated CO 2 but Acer did not. However, the observed effects of CO 2 on root production and loss did not alter the allometric relationship between root production and root loss for either Acer or Betula. Thus, in this experiment, elevated CO 2 did not affect the relationship between root production and root loss. The results of this study have important implications for the potential effects of elevated CO 2 on root dynamics. Elevated CO 2 may lead to increases in root production and in root loss (turnover) where the changes in root turnover are largely a function of the magnitude of root production increases.