Dynamics of ecosystem carbon balance recovering from a clear-cutting in a cool-temperate forest

著者: Aguilosa M., Takagi K., Liang N., Ueyama M., Fukuzawa K., Nomura M., Kishida O., Fukazawa T., Takahashi H., Kotsuka C., Sakai R., Ito K., Watanabe Y., Fujinuma Y., Takahashi Y., Murayama T., Saigusa N., Sasa K.
雑誌名: Agricultural and Forest Meteorology, 197, 26-39
DOI: -
概要: A mixed forest in northern Japan, which had been a weak carbon sink (net ecosystem CO₂ exchange [NEE] = −0.44 ± 0.5 Mg C ha⁻¹yr⁻¹), was disturbed by clear-cutting in 2003 and was replaced with a hybrid larch (Larix gmelinii × L. kaempferi) plantation in the same year. To evaluate the impact of the clear-cutting on the ecosystem’s carbon budget, we used 10.5 years (2001–2011) of eddy covariance measurements of CO₂ fluxes and the biomass observation for each ecosystem component. BIOME-BGC model was applied to simulate the changes in the carbon fluxes and stocks caused by the clear-cutting. After clear-cutting in 2003, the ecosystem abruptly became a large carbon source. The total CO₂ emission during the first 3 years after the disturbance (2003–2005) was 12.2 ± (0.9–1.5; possible min–max range of the error) Mg C ha⁻¹, yet gradually decreased to 2.5 ± (1–2) Mg C ha⁻¹ during the next 4 years. By 2010,the ecosystem had regained its status as a carbon sink (NEE = −0.49 ± 0.5 Mg C ha⁻¹yr⁻¹). Total gross primary production, ecosystem respiration, and NEE during the 7 years after the clear-cutting (2003–2009) were 64.5 ± (2.6–7), 79.2 ± (2.6–7), and 14.7 ± (1.3–3.5) Mg C ha⁻¹, respectively. From 2003 to 2009, the understory Sasa biomass increased by 16.3 ± 4.8 Mg C ha⁻¹, whereas the newly planted larch only gained1.00 ± 0.02 Mg C ha⁻¹. The BIOME-BGC simulated observed carbon fluxes and stocks, although further modification on the parameter set may be needed according with the tree growth and corresponding suppression of Sasa growth. Ecosystem carbon budget evaluation and the model simulation suggested that the litter including harvest residues became a large carbon emitter (∼31.9 Mg C ha⁻¹) during the same period. Based on the cumulative NEE during the period when the forest was a net carbon source, we estimate that the ecosystem will require another 8–34 years to fully recover all of the CO₂ that was emitted after the clear-cutting, if off-site carbon storage in forest products is not considered.