Partitioning of respired CO2 in newly sprouted Moso bamboo culms

Stem respiration (R-s) plays a vital role in ecosystem carbon cycling. However, the measured efflux on the stem surface (E-s) is not always in situ R-s but only part of it. A previously proposed mass balance framework (MBF) attempted to explore the multiple partitioning pathways of R-s, including sap-flow-transported and internal storage of R-s,R- in addition to E-s. This study proposed stem photosynthesis as an additional partitioning pathway to the MBF. Correspondingly, a double-chamber apparatus was designed and applied on newly sprouted Moso bamboo (Phyllostachys edulis) in leafless and leaved stages. R-s of newly sprouted bamboo were twice as high in the leafless stage (7.41 +/- 2.66 mu mol m(-2) s(-1)) than in the leaved stage (3.47 +/- 2.43 mu mol m(-2) s(-1)). E-s accounted for similar to 80% of R-s,R- while sap flow may take away similar to 2% of R-s in both leafless and leaved stages. Culm photosynthesis accounted for similar to 9% and 13% of R-s, respectively. Carbon sequestration from culm photosynthesis accounted for approximately 2% of the aboveground bamboo biomass in the leafless stage. High culm photosynthesis but low sap flow during the leafless stage and vice versa during the leaved stage make bamboo an outstanding choice for exploring the MBF.

Automated summary

Stem respiration is an important process in ecosystem carbon cycling. However, the measured efflux on the stem surface may not represent the actual respiration. This study proposes stem photosynthesis as an additional pathway and conducts experiments on newly sprouted bamboo to explore the partitioning of stem respiration.