Carbon dioxide exchange of a larch forest after a typhoon disturbance

A typhoon event catastrophically destroyed a 45-year-old Japanese larch plantation in southern Hokkaido, northern Japan in September 2004, and about 90% of trees were blown down. Vegetation was measured to investigate its regeneration process and CO2 flux, or net ecosystem production (NEP), was measured in 2006-2008 using an automated chamber system to investigate the effects of typhoon disturbance on the ecosystem carbon balance. Annual maximum aboveground biomass (AGB) increased from 2.7 Mg ha(-1) in 2006 to 4.0 Mg ha(-1) in 2007, whereas no change occurred in annual maximum leaf area index (LAI), which was 3.7 m(2) m(-2) in 2006 and 3.9 m(2) m(-2) in 2007. Red raspberry (Rubus idaeus) had become dominant within 2 years after the typhoon disturbance, and came to account for about 60% and 50% of AGB and LAI, respectively. In comparison with CO2 fluxes measured by the eddy covariance technique in 2001-2003, for 4.5 months during the growing season, the sum of gross primary production (GPP) decreased on average by 739 gC m(-2) (64%) after the disturbance, whereas ecosystem respiration (RE) decreased by 501 gC m(-2) (51%). As a result, NEP decreased from 159 +/- 57 gC m(-2) to -80 +/- 30 gC m(-2), which shows that the ecosystem shifted from a carbon sink to a source. Seasonal variation in RE was strongly correlated to soil temperature. The interannual variation in the seasonal trend of RE was small. Light-saturated GPP (P-max) decreased from 30-45 mu mol m(-2) s(-1) to 8-12 mu mol m(-2) s(-1) during the summer season through the disturbance because of large reduction in LAI. (C) 2010 Elsevier B.V. All rights reserved.