A compartmentation approach to deconstruct ecosystem carbon fluxes of a Moso bamboo forest in subtropical China

Moso bamboo ( Phyllostachys edulis ) forests are a vital resource in subtropical China, known for their high carbon (C) sequestration capacity. However, the dynamic processes of C fluxes within each component (canopy, culm, and soil) and their individual contributions, particularly during on- and off-years, remain unclear. A 2-year field experiment was conducted to investigate the dynamics of C fluxes from the canopy, culm, and soil (partitioned into heterotrophic, rhizome, and stump respiration) and their contributions to net ecosystem productivity (NEP) in a representative Moso bamboo forest in the subtropical region of China. The average annual NEP of the Moso bamboo forest was 7.31 ± 2.76 t C·ha –1 . Specifically, the canopy’s annual net C uptake was 17.30 ± 3.23 tC·ha –1 , accounting for 237% of NEP. In contrast, C emissions from heterotrophs, culms, rhizomes, and stumps were 5.37 ± 1.20, 2.18 ± 1.05, 1.29 ± 0.04, and 1.15 ± 0.33 t C·ha –1 , accounting for −73%, −30%, −18%, and −16% of NEP, respectively. The NEP, net cumulative C uptake in the canopy, and C emissions from the respiration of heterotrophs and stumps were all significantly higher during on-years when compared to off-years, whereas C emissions from bamboo culms displayed opposite trends. These findings offer a new approach for quantifying the C budgets of Moso bamboo forests and provide valuable insights into the C cycling processes in forest ecosystems. • Contribution of each component of forest ecosystem to NEP was observed for the first time. • Average annual NEP of the Moso bamboo forest was 7.31 ± 2.76 t C ha -1 . • Canopy and culm contributed 237% and -30% to NEP, respectively. • Heterotrophic, rhizome and stump contributed -73%, -18% and -16%, respectively. • The NEP, canopy C uptake and soil C emissions were higher in on-year than off-year.